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		<title>Survey, GIS, GeoIntelligence Articles Available Again</title>
		<link>http://www.gpsworld.com/survey-gis-geointelligence-articles-available-again/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=survey-gis-geointelligence-articles-available-again</link>
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		<pubDate>Mon, 03 Jun 2013 23:00:35 +0000</pubDate>
		<dc:creator>GPS World staff</dc:creator>
				<category><![CDATA[Latest News]]></category>
		<category><![CDATA[Tracy Cozzens]]></category>

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		<description><![CDATA[Are you looking for an article you read in GPS World or one of its newsletters? Because of a server move in 2012, much of our older content disappeared from the websites of both GPS World and its sister publication Geospatial Solutions. We have been working hard to again make this content available to our [...]]]></description>
				<content:encoded><![CDATA[<p>Are you looking for an article you read in <em>GPS World</em> or one of its newsletters? Because of a server move in 2012, much of our older content disappeared from the websites of both <a href="http://www.gpsworld.com/" target="_blank"><em>GPS World</em></a> and its sister publication <a href="http://geospatial-solutions.com/" target="_blank"><em>Geospatial Solutions</em></a>. We have been working hard to again make this content available to our readers.</p>
<p>As of today, we are happy to share that the following is again available:</p>
<ul>
<li>Content of every issue of <em>GPS World</em> magazine from mid-2010 to the present (our <a href="http://www.gpsworld.com/resources/archives/" target="_blank">archives</a> have issues back to July 2009);</li>
<li>All columns from the <a href="http://www.gpsworld.com/category/survey/survey-scene/" target="_blank"><em>Survey Scene</em></a> newsletter, written by Eric Gakstatter;</li>
<li>All columns from the <a href="http://geospatial-solutions.com/category/gss-monthly/" target="_blank"><em>GSS Monthly</em> and <em>GSS Weekly</em></a> newsletter written, by Eric Gakstatter;</li>
<li>All columns from the <em><a href="http://geospatial-solutions.com/category/geointelligence-insider/" target="_blank">GeoIntelligence Insider</a></em> newsletter, written by Art Kalinksi.</li>
</ul>
<p>Columns from our other newsletters are still being reposted; however, most of the columns from 2011 to the present are now available. These newsletters and authors include:</p>
<ul>
<li><a href="http://www.gpsworld.com/category/lbs-wireless/wireless-pulse/" target="_blank"><em>Wireless Pulse</em></a>, by Janice Partyka</li>
<li><a href="http://www.gpsworld.com/category/defense/defense-pnt-newsletter/" target="_blank"><em>Defense PNT</em></a>, by Don Jewell</li>
<li><a href="http://www.gpsworld.com/category/lbs-wireless/lbs-insider/" target="_blank"><em>LBS Insider</em></a>, by Kevin Dennehy</li>
<li><a href="http://www.gpsworld.com/category/oem/professional-oem-newsletter/" target="_blank"><em>Professional OEM</em></a>, by Tony Murfin</li>
</ul>
<p>If you are looking for a particular feature and are unable to find it, we will try to track it down for you. Please email <a href="mailto:editor@gpsworld.com" target="_blank">editor@gpsworld.com </a>with any past-article requests.</p>
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		<title>Innovation: GNSS Spoofing Detection: Correlating Carrier Phase with Rapid Antenna Motion</title>
		<link>http://www.gpsworld.com/innovation-gnss-spoofing-detection-correlating-carrier-phase-with-rapid-antenna-motion/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=innovation-gnss-spoofing-detection-correlating-carrier-phase-with-rapid-antenna-motion</link>
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		<pubDate>Sat, 01 Jun 2013 17:40:47 +0000</pubDate>
		<dc:creator>Richard Langley</dc:creator>
				<category><![CDATA[GNSS]]></category>
		<category><![CDATA[Innovation]]></category>
		<category><![CDATA[Richard B. Langley]]></category>
		<category><![CDATA[meaconing]]></category>
		<category><![CDATA[spoofing]]></category>

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		<description><![CDATA[By Mark L. Psiaki with Steven P. Powell and Brady W. O’Hanlon IT’S A HOSTILE (ELECTRONIC) WORLD OUT THERE, PEOPLE. Our wired and radio-based communication systems are constantly under attack from evil doers. We are all familiar with computer viruses and worms hiding in malicious software or malware distributed over the Internet or by infected [...]]]></description>
				<content:encoded><![CDATA[<p><em>By Mark L. Psiaki with Steven P. Powell and Brady W. O’Hanlon</em></p>
<div id="attachment_730" class="wp-caption alignright" style="width: 129px"><a href="http://www.gpsworld.com/wp-content/uploads/2012/09/Langley-INTRO-T.jpg"><img class="size-full wp-image-730" alt="INNOVATION INSIGHTS with Richard Langley" src="http://www.gpsworld.com/wp-content/uploads/2012/09/Langley-INTRO-T.jpg" width="119" height="150" /></a><p class="wp-caption-text">INNOVATION INSIGHTS with Richard Langley</p></div>
<p><strong>IT’S A HOSTILE (ELECTRONIC) WORLD OUT THERE, PEOPLE.</strong> Our wired and radio-based communication systems are constantly under attack from evil doers. We are all familiar with computer viruses and worms hiding in malicious software or malware distributed over the Internet or by infected USB flash drives. Trojan horses are particularly insidious. These are programs concealing harmful code that can lead to many undesirable effects such as deleting a user’s files or installing additional harmful software. Such programs pass themselves off as benign, just like the “gift” the Greeks delivered to the Trojans as reported in Virgil’s Aeneid. This was a very early example of spoofing. Spoofing of Internet Protocol (IP) datagrams is particularly prevalent. They contain forged source IP addresses with the purpose of concealing the identity of the sender or impersonating another computing system.</p>
<p>To spoof someone or something is to deceive or hoax, passing off a deliberately fabricated falsehood made to masquerade as truth. The word “spoof” was introduced by the English stage comedian Arthur Roberts in the late 19th century. He invented a game of that name, which involved trickery and nonsense. Now, the most common use of the word is as a synonym for parody or satirize — rather benign actions. But it is the malicious use of spoofing that concerns users of electronic communications.</p>
<p>And it is not just wired communications that are susceptible to spoofing. Communications and other services using radio waves are, in principle, also spoofable. One of the first uses of radio-signal spoofing was in World War I when British naval shore stations sent transmissions using German ship call signs. In World War II, spoofing became an established military tactic and was extended to radar and navigation signals. For example, German bomber aircraft navigated using radio signals transmitted from ground stations in occupied Europe, which the British spoofed by transmitting similar signals on the same frequencies. They coined the term “meaconing” for the interception and rebroadcast of navigation signals (meacon = m(islead)+(b)eacon).</p>
<p>Fast forward to today. GPS and other GNSS are also susceptible to meaconing. From the outset, the GPS P code, intended for use by military and other so-called authorized users, was designed to be encrypted to prevent straightforward spoofing. The anti-spoofing is implemented using a secret “W” encryption code, resulting in the P(Y) code. The C/A code and the newer L2C and L5 codes do not have such protection; nor, for the most part, do the civil codes of other GNSS. But, it turns out, even the P(Y) code is not fully protected from sophisticated meaconing attacks.</p>
<p>So, is there anything that military or civil GNSS users can do, then, to guard against their receivers being spoofed by sophisticated false signals? In this month’s column, we take a look at a novel, yet relatively easily implemented technique that enables users to detect and sequester spoofed signals. It just might help make it a safer world for GNSS positioning, navigation, and timing.</p>
<hr />
<h6>“Innovation” is a regular feature that discusses advances in GPS technology andits applications as well as the fundamentals of GPS positioning. The column is coordinated by Richard Langley of the Department of Geodesy and Geomatics Engineering, University of New Brunswick. He welcomes comments and topic ideas. To contact him, see the “Contributing Editors” section on page 4.</h6>
<hr />
<p>The radionavigation community has known about the dangers of GNSS spoofing for a long time, as highlighted in the 2001 Volpe Report (see Further Reading). Traditional receiver autonomous integrity monitoring (RAIM) had been considered a good spoofing defense. It assumes a dumb spoofer whose false signal produces a random pseudorange and large navigation solution residuals. The large errors are easy to detect, and given enough authentic signals, the spoofed signal(s) can be identified and ignored.</p>
<p>That spoofing model became obsolete at The Institute of Navigation’s GNSS 2008 meeting. Dr. Todd Humphreys introduced a new receiver/spoofer that could simultaneously spoof all signals in a self-consistent way undetectable to standard RAIM techniques. Furthermore, it could use its GNSS reception capabilities and its known geometry relative to the victim to overlay the false signals initially on top of the true ones. Slowly it could capture the receiver tracking loops by raising the spoofer power to be slightly larger than that of the true signals, and then it could drag the victim receiver off to false, but believable, estimates of its position, time, or both.</p>
<p>Two of the authors of this article contributed to Humphreys’ initial developments. There was no intention to help bad actors deceive GNSS user equipment (UE). Rather, our goal was to field a formidable “Red Team” as part of a “Red Team/Blue Team” (foe/friend) strategy for developing advanced “Blue Team” spoofing defenses.</p>
<p>This seemed like a fun academic game until mid-December 2011, when news broke that the Iranians had captured a highly classified Central Intelligence Agency drone, a stealth Lockheed Martin RQ-170 Sentinel, purportedly by spoofing its GPS equipment. Given our work in spoofing and detection, this event caused quite a stir in our Cornell University research group, in Humphreys’ University of Texas at Austin group, and in other places. The editor of this column even got involved in our extensive e-mail correspondence. Two key questions were: Wouldn’t a classified spy drone be equipped with a Selective Availability Anti-Spoofing Module (SAASM) receiver and, therefore, not be spoofable? Isn’t it difficult to knit together a whole sequence of false GPS position fixes that will guide a drone to land in a wrong location? These issues, when coupled with apparent inconsistencies in the Iranians’ story and visible damage to the drone, led us to discount the spoofing claim.</p>
<p><b>Developing a New Spoofing Defense</b></p>
<p>My views about the Iranian claims changed abruptly in mid-April 2012. Todd Humphreys phoned me about an upcoming test of GPS jammers, slated for June 2012 at White Sands Missile Range (WSMR), New Mexico. The Department of Homeland Security (DHS) had already spent months arranging these tests, but Todd revealed something new in that call: He had convinced the DHS to include a spoofing test that would use his latest “Red Team” device. The goal would be to induce a small GPS-guided unmanned aerial vehicle (UAV), in this case a helicopter, to land when it was trying to hover. “Wow”, I thought. “This will be a mini-replication of what the Iranians claimed to have done to our spy drone, and I’m sure that Todd will pull it off. I want to be there and see it.” Cornell already had plans to attend to test jammer tracking and geolocation, but we would have to come a day early to see the spoofing “fun” — if we could get permission from U.S. Air Force 746th Test Squadron personnel at White Sands.</p>
<p>The implications of the UAV test bounced around in my head that evening and the next morning on my seven-mile bike commute to work. During that ride, I thought of a scenario in which the Iranians might have mounted a meaconing attack against a SAASM-equipped drone. That is, they might possibly have received and re-broadcast the wide-band P(Y) code in a clever way that could have nudged the drone off course and into a relatively soft landing on Iranian territory.</p>
<p>In almost the next moment, I conceived a defense against such an attack. It involves small antenna motions at a high frequency, the measurement of corresponding carrier-phase oscillations, and the evaluation of whether the motions and phase oscillations are more consistent with spoofed signals or true signals. This approach would yield a good defense for civilian and military receivers against both spoofing and meaconing attacks. The remainder of this article describes this defense and our efforts to develop and test it.</p>
<p>It is one thing to conceive an idea, maybe a good idea. It is quite another thing to bring it to fruition. This idea seemed good enough and important enough to “birth” the conception. The needed follow-up efforts included two parts, one theoretical and the other experimental.</p>
<p>The theoretical work involved the development of signal models, hypothesis tests, analyses, and software. It culminated in analysis and truth-model simulation results, which showed that the system could be very practical, using only centimeters of motion and a fraction of a second of data to reliably differentiate between spoofing attacks and normal GNSS operation.</p>
<p>Theories and analyses can contain fundamental errors, or overlooked real-world effects can swamp the main theoretical effect. Therefore, an experimental prototype was quickly conceived, developed, and tested. It consisted of a very simple antenna-motion system, an RF data-recording device, and after-the-fact signal processing. The signal processing used Matlab to perform the spoofing detection calculations after using a C-language software radio to perform standard GPS acquisition and tracking.</p>
<p>Tests of the non-spoofed case could be conducted anywhere outdoors. Our initial tests occurred on a Cornell rooftop in Ithaca, New York. Tests of the spoofed case are harder. One cannot transmit live spoofing signals except with special permission at special times and in special places, for example, at WSMR in the upcoming June tests. Fortunately, the important geometric properties of spoofed signals can be simulated by using GPS signal reception at an outdoor antenna and re-radiation in an anechoic chamber from a single antenna. Such a system was made available to us by the NASA facility at Wallops Island, Virginia, and our simulated spoofed-case testing occurred in late April of last year. All of our data were processed before mid-May, and they provided experimental confirmation of our system’s efficacy. The final results were available exactly three busy weeks after the initial conception.</p>
<p>Although we were convinced about our new system, we felt that the wider GNSS community would like to see successful tests against live-signal attacks by a real spoofer. Therefore, we wanted very much to bring our system to WSMR for the June 2012 spoofing attack on the drone. We could set up our system near the drone so that it would be subject to the same malicious signals, but without the need to mount our clumsy prototype on a compact UAV helicopter. We were concerned, however, about the possibility of revealing our technology before we had been able to apply for patent protection. After some hesitation and discussions with our licensing and technology experts, we decided to bring our system to the WSMR test, but with a physical cover to keep it secret. The cover consisted of a large cardboard box, large enough to accommodate the needed antenna motions. The WSMR data were successfully collected using this method. Post-processing of the data demonstrated very reliable differentiation between spoofed and non-spoofed cases under live-signal conditions, as will be described in subsequent sections of this article.</p>
<p><b>System Architecture and Prototype</b></p>
<p>The components and geometry of one possible version of this system are shown in FIGURE 1. The figure shows three of the GNSS satellites whose signals would be tracked in the non-spoofed case: satellites <i>j</i>-1, <i>j</i>, and <i>j</i>+1. It also shows the potential location of a spoofer that could send false versions of the signals from these same satellites. The spoofer has a single transmission antenna. Satellites <i>j</i>-1, <i>j</i>, and <i>j</i>+1 are visible to the receiver antenna, but the spoofer could “hijack” the receiver’s tracking loops for these signals so that only the false spoofed versions of these signals would be tracked by the receiver.</p>
<div id="attachment_21505" class="wp-caption alignnone" style="width: 586px"><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig1.jpg"><img class=" wp-image-21505 " alt="Figure 1. Spoofing detection antenna articulation system geometry relative to base mount, GNSS satellites, and potential spoofer." src="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig1.jpg" width="576" height="352" /></a><p class="wp-caption-text">Figure 1. Spoofing detection antenna articulation system geometry relative to base mount, GNSS satellites, and potential spoofer.</p></div>
<p>The receiver antenna mount enables its phase center to be moved with respect to the mounting base. In Figure 1, this motion system is depicted as an open kinematic chain consisting of three links with ball joints. This is just one example of how a system can be configured to allow antenna motion. Spoofing detection can work well with just one translational degree of freedom, such as a piston-like up-and-down motion that could be provided by a solenoid operating along the <i>z<sub>a</sub></i> articulation axis. It would be wise to cover the motion system with an optically opaque radome, if possible, to prevent a spoofer from defeating this system by sensing the high-frequency antenna motions and spoofing their effects on carrier phase.</p>
<p>Suppose that the antenna articulation time history in its local body-fixed (<i>x<sub>a</sub></i>, <i>y<sub>a</sub></i>, <i>z<sub>a</sub></i>) coordinate system is <b><i>b</i></b><sub>a</sub>(<i>t</i>). Then the received carrier phases are sensitive to the projections of this motion onto the line-of-sight (LOS) directions of the received signals. These projections are along  <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj1.jpg"><img class="alignnone  wp-image-21612" alt="Eq-rj1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj1.jpg" width="22" height="16" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg"><img class="alignnone  wp-image-21611" alt="Eq-rj" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg" width="14" height="16" /></a>, and  <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-r-j+1.jpg"><img class="alignnone  wp-image-21610" alt="Eq-r-j+1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-r-j+1.jpg" width="25" height="17" /></a> in the non-spoofed case, with <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg"><img alt="Eq-rj" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg" width="14" height="16" /></a>  being the known unit direction vector from the <i>j</i>th GNSS satellite to the nominal antenna location. In the spoofed case, the projections are all along <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg"><img class="alignnone  wp-image-21613" alt="Eq-rsp" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg" width="22" height="15" /></a>, regardless of which signal is being spoofed, with <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg"><img class="alignnone  wp-image-21613" alt="Eq-rsp" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg" width="22" height="15" /></a> being the unknown unit direction vector from the spoofer to the victim antenna. Thus, there will be differences between the carrier-phase responses of the different satellites in the non-spoofed case, but these differences will vanish in the spoofed case. This distinction lies at the heart of the new spoofing detection method. Given that a good GNSS receiver can easily distinguish quarter-cycle carrier-phase variations, it is expected that this system will be able to detect spoofing using antenna motions as small as 4.8 centimeters, that is, a quarter wavelength of the GPS L1 signal.</p>
<p>The UE receiver and spoofing detection block in Figure 1 consists of a standard GNSS receiver, a means of inputting the antenna motion sensor data, and additional signal processing downstream of the standard GNSS receiver operations. The latter algorithms use as inputs the beat carrier-phase measurements from a standard phase-locked loop (PLL).</p>
<p>It may be necessary to articulate the antenna at a frequency nearly equal to the bandwidth of the PLL (say, at 1 Hz or higher). In this case, special post-processing calculations might be required to reconstruct the high-frequency phase variations accurately before they can be used to detect spoofing. The needed post-processing uses the in-phase and quadrature accumulations of a phase discriminator to reconstruct the noisy phase differences between the true signal and the PLL numerically controlled oscillator (NCO) signal. These differences are added to the NCO phases to yield the full high-bandwidth variations.</p>
<p>We implemented the first prototype of this system with one-dimensional antenna motion by mounting its patch antenna on a cantilevered beam. It is shown in FIGURE 2. Motion is initiated by pulling on the string shown in the upper left-hand part of the figure. Release of the string gives rise to decaying sinusoidal oscillations that have a frequency of about 2 Hz.</p>
<div id="attachment_21506" class="wp-caption alignnone" style="width: 586px"><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig2.jpg"><img class=" wp-image-21506 " alt="Figure 2. Antenna articulation system for first prototype spoofing detector tests: a cantilevered beam that allows single-degree-of-freedom antenna phase-center vibration along a horizontal axis." src="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig2.jpg" width="576" height="325" /></a><p class="wp-caption-text">Figure 2. Antenna articulation system for first prototype spoofing detector tests: a cantilevered beam that allows single-degree-of-freedom antenna phase-center vibration along a horizontal axis.</p></div>
<p>The remainder of the prototype system consisted of a commercial-off-the-shelf RF data recording device, off-line software receiver code, and off-line spoofing detection software. The prototype system lacked an antenna motion sensor. We compensated for this omission by implementing additional signal-processing calculations. They included off-line parameter identification of the decaying sinusoidal motions coupled with estimation of the oscillations’ initial amplitude and phase for any given detection.</p>
<p>This spoofing detection system is not the first to propose the use of antenna motion to uncover spoofing, and it is related to techniques that rely on multiple antennas. The present system makes three new contributions to the art of spoofing detection: First, it clearly explains why the measured carrier phases from a rapidly oscillating antenna provide a good means to detect spoofing. Second, it develops a precise spoofing detection hypothesis test for a moving-antenna system. Third, it demonstrates successful spoofing detection against live-signal attacks by a “Humphreys-class” spoofer.</p>
<p><b>Signal Model Theory and Verification</b></p>
<p>The spoofing detection test relies on mathematical models of the response of beat carrier phase to antenna motion. Reasonable models for the non-spoofed and spoofed cases are, respectively:</p>
<p><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-1b1.jpg"><img class="alignnone  wp-image-21615" alt="Eq-1b" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-1b1.jpg" width="569" height="47" /></a>  (1a)</p>
<p><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-1a.jpg"><img alt="Eq-1a" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-1a.jpg" width="571" height="46" /></a>(1b)</p>
<p>where <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-0jk.jpg"><img class="alignnone  wp-image-21607" alt="Eq-0jk" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-0jk.jpg" width="18" height="25" /></a> is the received (negative) beat carrier phase of the authentic or spoofed satellite-<i>j</i> signal at the <i>k</i>th sample time <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tjmk.jpg"><img class="alignnone  wp-image-21614" alt="Eq-tjmk" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tjmk.jpg" width="29" height="20" /></a> . The three-by-three direction cosines matrix <b><i>A</i></b> is the transformation from the reference system, in which the direction vectors <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg"><img class="alignnone  wp-image-21611" alt="Eq-rj" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg" width="14" height="16" /></a>  and <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg"><img class="alignnone  wp-image-21613" alt="Eq-rsp" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg" width="22" height="15" /></a> are defined, to the local body-axis system, in which the antenna motion <b><i>b</i></b><i><sub>a</sub></i>(<i>t</i>) is defined. <em>λ</em> is the nominal carrier wavelength. The terms involving the unknown polynomial coefficients <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg"><img class="alignnone  wp-image-21619" alt="Eq-Bj0" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg" width="18" height="21" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg"><img class="alignnone  wp-image-21618" alt="Eq-Bj1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg" width="19" height="22" /></a> , and <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg"><img class="alignnone  wp-image-21617" alt="Eq-Bj2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg" width="22" height="22" /></a> model other low-frequency effects on carrier phase, including satellite motion, UE motion if its antenna articulation system is mounted on a vehicle, and receiver clock drift. The term <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-nj0k.jpg"><img class="alignnone  wp-image-21621" alt="Eq-nj0k" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-nj0k.jpg" width="23" height="26" /></a> is the receiver phase noise. It is assumed to be a zero-mean, Gaussian, white-noise process whose variance depends on the receiver carrier-to-noise-density ratio and the sample/accumulation frequency.</p>
<p>If the motion of the antenna is one-dimensional, then <b><i>b</i></b><i><sub>a</sub></i>(<i>t</i>) takes the form <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-ba1.jpg"><img class="alignnone  wp-image-21623" alt="Eq-ba1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-ba1.jpg" width="92" height="22" /></a>, with <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-ba.jpg"><img class="alignnone  wp-image-21622" alt="Eq-ba" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-ba.jpg" width="16" height="22" /></a> being the articulation direction in body-axis coordinates and <i>r</i><i><sub>a</sub></i>(<i>t</i>) being a known scalar antenna deflection amplitude time history. If one defines the articulation direction in reference coordinates as <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-ra.jpg"><img class="alignnone  wp-image-21624" alt="Eq-ra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-ra.jpg" width="73" height="29" /></a> , then the carrier-phase models in Equations (1a) and (1b) become</p>
<p><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-2a.jpg"><img class="alignnone  wp-image-21625" alt="Eq-2a" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-2a.jpg" width="564" height="47" /></a>   (2a)</p>
<p><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-2b.jpg"><img class="alignnone  wp-image-21626" alt="Eq-2b" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-2b.jpg" width="569" height="44" /></a>  (2b)</p>
<p>There is one important feature of these models for purposes of spoofing detection. In the non-spoofed case, the term that models the effects of antenna motion varies between GPS satellites because the <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg"><img class="alignnone  wp-image-21611" alt="Eq-rj" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg" width="14" height="16" /></a> direction vector varies with <i>j</i>. The spoofed case lacks variation between the satellites because the one spoofer direction <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg"><img alt="Eq-rsp" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg" width="22" height="15" /></a> replaces <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg"><img alt="Eq-rj" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg" width="14" height="16" /></a> for all of the spoofed satellites. This becomes clear when one compares the first terms on the right-hand sides of Eqsuations (1a) and (1b) for the 3-D motion case and on the right-hand sides of Equations (2a) and (2b) for the 1-D case.</p>
<p>The carrier-phase time histories in FIGURES 3 and 4 illustrate this principle. These data were collected at WSMR using the prototype antenna motion system of Figure 2. The carrier-phase time histories have been detrended by estimating the <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg"><img alt="Eq-Bj0" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg" width="18" height="21" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg"><img alt="Eq-Bj1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg" width="19" height="22" /></a> , and <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg"><img alt="Eq-Bj2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg" width="22" height="22" /></a> coefficients in Equations (2a) and (2b) and subtracting off their effects prior to plotting. In Figure 3, all eight satellite signals exhibit similar decaying sinusoid time histories, but with differing amplitudes and some of them with sign changes. This is exactly what is predicted by the 1-D non-spoofed model in Equation (2a). All seven spoofed signals in Figure 4, however, exhibit identical decaying sinusoidal oscillations because the <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp-tra.jpg"><img alt="Eq-rsp-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp-tra.jpg" width="53" height="22" /></a> term in Equation (2b) is the same for all of them.</p>
<div id="attachment_21507" class="wp-caption alignnone" style="width: 610px"><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig3.jpg"><img class=" wp-image-21507 " alt="Figure 3. Detrended carrier-phase data from multiple satellites for a typical non-spoofed case using a 1-D antenna articulation system." src="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig3.jpg" width="600" height="386" /></a><p class="wp-caption-text">Figure 3. Detrended carrier-phase data from multiple satellites for a typical non-spoofed case using a 1-D antenna articulation system.</p></div>
<p>&nbsp;</p>
<div id="attachment_21508" class="wp-caption alignnone" style="width: 610px"><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig4.jpg"><img class=" wp-image-21508 " alt="Figure 4. Multiple satellites’ detrended carrier-phase data for a typical spoofed case using a 1-D antenna articulation system." src="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig4.jpg" width="600" height="396" /></a><p class="wp-caption-text">Figure 4. Multiple satellites’ detrended carrier-phase data for a typical spoofed case using a 1-D antenna articulation system.</p></div>
<p>As an aside, an interesting feature of Figure 3 is its evidence of the workings of the prototype system. The ramping phases of all the signals from <i>t</i> = 0.4 seconds to <i>t</i> = 1.4 seconds correspond to the initial pull on the string shown in Figure 2, and the steady portion from <i>t</i> = 1.4 seconds to <i>t</i> = 2.25 seconds represents a period when the string was held fixed prior to release.<b><br />
</b></p>
<p><b>Spoofing Detection Hypothesis Test</b></p>
<p>A hypothesis test can precisely answer the question of which model best fits the observed data: Does carrier-phase sameness describe the data, as in Figure 4? Then the receiver is being spoofed. Alternatively, is carrier-phase differentness more reasonable, as per Figure 3? Then the signals are trustworthy.</p>
<p>A hypothesis test can be developed for any batch of carrier-phase data that spans a sufficiently rich antenna motion profile <b><i>b</i></b><i><sub>a</sub></i>(<i>t</i>) or <em>ρ</em><i><sub>a</sub></i>(<i>t</i>). The profile must include high-frequency motions that cannot be modeled by the  <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg"><img alt="Eq-Bj0" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg" width="18" height="21" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg"><img alt="Eq-Bj1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg" width="19" height="22" /></a> , and <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg"><img alt="Eq-Bj2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg" width="22" height="22" /></a>quadratic polynomial terms in Equations (1a)-(2b); otherwise the detection test will lose all of its power. A motion profile equal to one complete period of a sine wave has the needed richness.</p>
<p>Suppose one starts with a data batch that is comprised of carrier-phase time histories for <i>L</i> different GNSS satellites: <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-0jk.jpg"><img class="alignnone  wp-image-21607" alt="Eq-0jk" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-0jk.jpg" width="18" height="25" /></a> for samples <i>k</i> = 1, &#8230;, <i>M</i><i><sub>j</sub></i> and for satellites <i>j</i> = 1,&#8230;, <i>L</i>. A standard hypothesis test develops two probability density functions for these data, one conditioned on the null hypothesis of no spoofing, <i>H</i><sub>0</sub>, and the other conditioned on the hypothesis of spoofing, <i>H</i><sub>1</sub>.  The Neyman-Pearson lemma (see Further Reading) proves that the optimal hypothesis test statistic equals the ratio of these two probability densities. Unfortunately, the required probability densities depend on additional unknown quantities. In the 1-D motion case, these unknowns include the <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg"><img alt="Eq-Bj0" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg" width="18" height="21" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg"><img alt="Eq-Bj1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg" width="19" height="22" /></a> , and <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg"><img alt="Eq-Bj2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg" width="22" height="22" /></a> coefficients, the dot product <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp-tra.jpg"><img class="alignnone  wp-image-21627" alt="Eq-rsp-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp-tra.jpg" width="53" height="22" /></a>, and the direction <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img class="alignnone  wp-image-21628" alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a>  if one assumes that the UE attitude is unknown. A true Neyman-Pearson test would hypothesize <i>a priori</i> distributions for these unknown quantities and integrate their dependencies out of the two joint probability distributions. Our sub-optimum test optimally estimates relevant unknowns for each hypothesis based on the carrier-phase data, and it uses these estimates in the Neyman-Pearson probability density ratio. Although sub-optimal as a hypothesis test, this approach is usually effective, and it is easier to implement than the integration approach in the present case.</p>
<p>Consider the case of 1-D antenna articulation and unknown UE attitude. Maximum-likelihood calculations optimally estimate the nuisance parameters  <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg"><img alt="Eq-Bj0" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg" width="18" height="21" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg"><img alt="Eq-Bj1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg" width="19" height="22" /></a> , and <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg"><img alt="Eq-Bj2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg" width="22" height="22" /></a>  for <i>j</i> = 1, &#8230;, <i>L</i> for both hypotheses along with the unit vector <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a> for the non-spoofed hypothesis, or the scalar dot product <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-nsix.jpg"><img class="alignnone  wp-image-21629" alt="Eq-nsix" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-nsix.jpg" width="79" height="23" /></a> for the spoofed hypothesis. The estimation calculations for each hypothesis minimize the negative natural logarithm of the corresponding conditional probability density. Because  <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg"><img alt="Eq-Bj0" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg" width="18" height="21" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg"><img alt="Eq-Bj1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg" width="19" height="22" /></a> , and <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg"><img alt="Eq-Bj2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg" width="22" height="22" /></a> enter the resulting cost functions quadratically, their optimized values can be computed as functions of the other unknowns, and they can be substituted back into the costs. This part of the calculation amounts to a batch high-pass filter of both the antenna motion and the carrier-phase response.</p>
<p>The remaining optimization problems take, under the non-spoofed hypothesis, the form:</p>
<p>find:      <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img class="alignnone  wp-image-21628" alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="17" height="24" /></a>    (3a)</p>
<p>to minimize:       <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp.jpg"><img class="alignnone  wp-image-21630" alt="Eq-Jnonsp" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp.jpg" width="272" height="54" /></a>  (3b)</p>
<p>subject to:             <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rasmall.jpg"><img class="alignnone  wp-image-21634" alt="Eq-rasmall" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rasmall.jpg" width="89" height="26" /></a>   (3c)</p>
<p>and, under the spoofed hypothesis, the form:</p>
<p>find:     <strong> <em>η</em></strong>    (4a)</p>
<p>to minimize:   <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jspn.jpg"><img class="alignnone  wp-image-21632" alt="Eq-Jspn" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jspn.jpg" width="199" height="53" /></a>      (4b)</p>
<p>subject to:     <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-111.jpg"><img class="alignnone  wp-image-21631" alt="Eq-111" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-111.jpg" width="83" height="20" /></a> .   (4c)</p>
<p>The coefficient <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj44.jpg"><img class="alignnone  wp-image-21637" alt="Eq-rj44" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj44.jpg" width="27" height="26" /></a> is a function of the deflections <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Pat.jpg"><img class="alignnone  wp-image-21638" alt="Eq-Pat" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Pat.jpg" width="74" height="27" /></a> for <i>k</i> = 1, &#8230;, <i>M</i><i><sub>j</sub></i>, and the non-homogenous term <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-zj4.jpg"><img class="alignnone  wp-image-21639" alt="Eq-zj4" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-zj4.jpg" width="20" height="27" /></a> is derived from the <i>j</i>th phase time history <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-0jk.jpg"><img class="alignnone  wp-image-21607" alt="Eq-0jk" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-0jk.jpg" width="18" height="25" /></a> for <i>k</i> = 1, &#8230;, <i>M</i><i><sub>j</sub></i>. These two quantities are calculated during the  <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg"><img alt="Eq-Bj0" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg" width="18" height="21" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg"><img alt="Eq-Bj1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg" width="19" height="22" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg"><img alt="Eq-Bj2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg" width="22" height="22" /></a> optimization. The constraint in Equation (3c) forces the estimate of the antenna articulation direction to be unit-normalized. The constraint in Eq. (4c) ensures that <em>η</em> is a physically reasonable dot product.</p>
<p>The optimization problems in Equations (3a)-(3c) and (4a)-(4c) can be solved in closed form using techniques from the literature on constrained optimization, linear algebra, and matrix factorization. The optimal estimates of <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img class="alignnone  wp-image-21628" alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="17" height="24" /></a> and <em>η</em> can be used to define a spoofing detection statistic that equals the natural logarithm of the Neyman-Pearson ratio:</p>
<p><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-y-small.jpg"><img class="alignnone  wp-image-21640" alt="Eq-y-small" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-y-small.jpg" width="196" height="29" /></a>(5)</p>
<p>It is readily apparent that <em>γ</em> constitutes a reasonable test statistic: If the signal is being spoofed so that carrier-phase sameness is the best model, then <em>η</em><i><sub>opt</sub></i> will produce a small value of  <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jsp-n.jpg"><img class="alignnone  wp-image-21642" alt="Eq-Jsp-n" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jsp-n.jpg" width="59" height="22" /></a>because the spoofed-case cost function in Equation (4b) is consistent with carrier-phase sameness. The value of <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp-r.jpg"><img class="alignnone  wp-image-21641" alt="Eq-Jnonsp-r" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp-r.jpg" width="76" height="21" /></a>, however, will not be small because the plurality of  <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg"><img class="alignnone  wp-image-21611" alt="Eq-rj" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg" width="14" height="16" /></a> directions in Equation (3b) precludes the possibility that any <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img class="alignnone  wp-image-21628" alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a> estimate will yield a small non-spoofed cost. Therefore, <em>γ</em> will tend to be a large negative number in the event of spoofing because <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp-r.jpg"><img alt="Eq-Jnonsp-r" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp-r.jpg" width="76" height="21" /></a> &gt;&gt; <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jsp-n.jpg"><img alt="Eq-Jsp-n" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jsp-n.jpg" width="59" height="22" /></a> is likely. In the non-spoofed case, the opposite holds true: <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-ropt.jpg"><img class="alignnone  wp-image-21645" alt="Eq-ropt" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-ropt.jpg" width="26" height="20" /></a>  will yield a small value of <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp-r.jpg"><img alt="Eq-Jnonsp-r" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp-r.jpg" width="76" height="21" /></a>, but no estimate of <em>η</em> will yield a small <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-jspn2.jpg"><img class="alignnone  wp-image-21646" alt="Eq-jspn2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-jspn2.jpg" width="46" height="24" /></a>, and <em>γ</em> will be a large positive number because  <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp-r.jpg"><img alt="Eq-Jnonsp-r" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jnonsp-r.jpg" width="76" height="21" /></a>&lt;&lt; <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jsp-n.jpg"><img alt="Eq-Jsp-n" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Jsp-n.jpg" width="59" height="22" /></a>.</p>
<p>Therefore, a sensible spoofing detection test employs a detection threshold <em>γ</em><i><sub>th</sub></i> somewhere in the neighborhood of zero. The detection test computes a <em>γ</em> value based on the carrier-phase data, the antenna articulation time history, and the calculations in Equations (3a)-(5). It compares this <em>γ</em> to <em>γ</em><i><sub>th</sub></i>. If <em>γ</em> ≥ <em>γ</em><i><sub>th</sub></i>, then the test indicates that there is no spoofing. If <em>γ</em> &lt; <em>γ</em><i><sub>th</sub></i>, then a spoofing alert is issued.</p>
<p>The exact choice of <em>γ</em><i><sub>th</sub></i> is guided by an analysis of the probability of false alarm. A false alarm occurs if a spoofing attack is declared when there is no spoofing. The false-alarm probability is determined as a function of <em>γ</em><i><sub>th</sub></i> by developing a <em>γ</em> probability density function under the null hypothesis of no spoofing <i>p</i>(<em>γ</em>|<i>H</i><sub>0</sub>). The probability of false alarm equals the integral of <i>p</i>(<em>γ</em>|<i>H</i><sub>0</sub>) from <em>γ</em> = <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-infinity.jpg"><img class="alignnone  wp-image-21649" alt="Eq-infinity" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-infinity.jpg" width="23" height="10" /></a> to <em>γ</em> = <em>γ</em><i><sub>th</sub></i>. This integral relationship can be inverted to determine the <em>γ</em><i><sub>th</sub></i> threshold that yields a given prescribed false-alarm probability</p>
<p>A complication arises because <i>p</i>(<em>γ</em>|<i>H</i><sub>0</sub>) depends on unknown parameters, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a>  in the case of an unknown UE attitude and 1-D antenna motion. Although sub-optimal, a reasonable way to deal with the dependence of <i>p</i>(<em>γ</em>|<a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a>,<i>H</i><sub>0</sub>) on <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a> is to use the worst-case <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a> for a given <em>γ</em><i><sub>th</sub></i>. The worst-case articulation direction <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rawc.jpg"><img class="alignnone  wp-image-21650" alt="Eq-rawc" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rawc.jpg" width="27" height="20" /></a> maximizes the <i>p</i>(<em>γ</em>|<a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a>,<i>H</i><sub>0</sub>) false-alarm integral. It can be calculated by solving an optimization problem. This analysis can be inverted to pick <em>γ</em><i><sub>th</sub></i> so that the worst-case probability of false alarm equals some prescribed value. For most actual <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a> values, the probability of false alarm will be lower than the prescribed worst case.</p>
<p>Given <em>γ</em><i><sub>th</sub></i>, the final needed analysis is to determine the probability of missed detection. This analysis uses the probability density function of <i>g</i> under the spoofed hypothesis, <i>p</i>(<em>γ</em>|<em>η</em>,<i>H</i><sub>1</sub>). The probability of missed detection is the integral of this function from <em>γ</em> = <em>γ</em><i><sub>th</sub></i> to <em>γ</em> = +<a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-infinity2.jpg"><img class="alignnone  wp-image-21651" alt="Eq-infinity2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-infinity2.jpg" width="13" height="10" /></a>. The dependence of <i>p</i>(<em>γ</em>|<em>η</em>,<i>H</i><sub>1</sub>) on the unknown dot product <em>η</em> can be handled effectively, though sub-optimally, by determining the worst-case probability of false alarm. This involves an optimization calculation, which finds the worst-case dot product <em>η</em><i><sub>wc</sub></i> that maximizes the missed-detection probability integral. Again, most actual <em>η</em> values will yield lower probabilities of missed detection.</p>
<p>Note that the above-described analyses rely on approximations of the probability density functions <i>p</i>(<em>γ</em>|<a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a>,<i>H</i><sub>0</sub>) and <i>p</i>(<em>γ</em>|<em>η</em>,<i>H</i><sub>1</sub>). The best approximations include dominant Gaussian terms plus small chi-squared or non-central chi-squared terms. It is difficult to analyze the chi-squared terms rigorously. Their smallness, however, makes the use of Gaussian approximations reasonable.</p>
<p>We have developed and evaluated several alternative formulations of this spoofing detection method. One is the case of full 3-D <b><i>b</i></b><i><sub>a</sub></i>(<i>t</i>) antenna motion with unknown UE attitude. The full direction cosines matrix <b><i>A</i></b> is estimated in the modified version of the non-spoofed optimal fit calculations of Equations (3a)-(3c), and the full spoofing direction vector <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-bsp.jpg"><img class="alignnone  wp-image-21652" alt="Eq-bsp" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-bsp.jpg" width="58" height="17" /></a> is estimated in the modified version of Equations (4a)-(4c). A different alternative allows the 1-D motion time history <em>ρ</em><i><sub>a</sub></i>(<i>t</i>) to have an unknown amplitude-scaling factor that must be estimated. This might be appropriate for a UAV drone with a wing-tip-mounted antenna if it induced antenna motions by dithering its ailerons. In fixed-based applications, as might be used by a financial institution, a cell-phone tower, or a power-grid monitor, the attitude would be known, which would eliminate the need to estimate <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a> or <b><i>A</i></b> for the non-spoofed case.</p>
<p><b>Test Results</b></p>
<p>The initial tests of our concept involved generation of simulated truth-model carrier-phase data <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-0jk.jpg"><img class="alignnone  wp-image-21607" alt="Eq-0jk" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-0jk.jpg" width="18" height="25" /></a> using simulated <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg"><img alt="Eq-Bj0" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj0.jpg" width="18" height="21" /></a>, <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg"><img alt="Eq-Bj1" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj1.jpg" width="19" height="22" /></a> , and <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg"><img alt="Eq-Bj2" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-Bj2.jpg" width="22" height="22" /></a> polynomial coefficients, simulated satellite LOS direction vectors <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg"><img class="alignnone size-full wp-image-21611" alt="Eq-rj" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg" width="18" height="20" /></a> for the non-spoofed cases, a simulated true spoofer LOS direction <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg"><img class="alignnone size-full wp-image-21613" alt="Eq-rsp" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rsp.jpg" width="27" height="19" /></a> for the spoofed cases, and simulated antenna motions parameterized by <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img class="alignnone size-full wp-image-21628" alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="21" height="30" /></a> and <em>ρ</em><i><sub>a</sub></i>(<i>t</i>). Monte-Carlo analysis was used to generate many different batches of phase data with different random phase noise realizations in order to produce simulated histograms of the <i>p</i>(<em>γ</em>|<a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a>, <i>H</i><sub>0</sub>) and <i>p</i>(<em>γ</em>|<em>η</em>,<i>H</i><sub>1</sub>) probability density functions  that are used in false-alarm and missed-detection analyses.</p>
<p>The truth-model simulations verified that the system is practical. A representative calculation used one cycle of an 8-Hz 1-D sinusoidal antenna oscillation with a peak-to-peak amplitude of 4.76 centimeters (exactly 1/4 of the L1 wavelength). The accumulation frequency was 1 kHz so that there were <i>M</i><i><sub>j</sub></i> = 125 carrier-phase measurements per satellite per data batch. The number of satellites was <i>L</i> = 6, their <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg"><img alt="Eq-rj" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-rj.jpg" width="18" height="20" /></a> LOS vectors were distributed to yield a geometrical dilution of precision of 3.5, and their carrier-to-noise-density ratios spanned the range 38.2 to 44.0 dB-Hz. The worst-case probability of a spoofing false alarm was set at 10<sup>-5</sup> and the corresponding worst-case probability of missed detection was 1.2 ´ 10<sup>-5</sup>. Representative non-worst-case probabilities of false alarm and missed detection were, respectively, 1.7 ´ 10<sup>-9</sup> and 1.1 ´ 10<sup>-6</sup>. These small numbers indicate that this is a very powerful test. Ten-thousand run Monte-Carlo simulations of the spoofed and non-spoofed cases verified the reasonableness of these probabilities and the reasonableness of the <i>p</i>(<em>γ</em>|<a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="15" height="21" /></a>, <i>H</i><sub>0</sub>) and <i>p</i>(<em>γ</em>|<em>η</em>,<i>H</i><sub>1</sub>) Gaussian approximations that had been used to derive them.</p>
<p>The live-signal tests bore out the truth-model simulation results. The only surprise in the live-signal tests was the presence of significant multipath, which was evidenced by received carrier amplitude oscillations that correlated with the antenna oscillations and whose amplitudes and phases varied among the different received GPS signals. As a verification that these oscillations were caused by multipath, the only live-signal data set without such amplitude oscillations was the one taken in the NASA Wallops anechoic chamber, where one would not expect to find multipath. The multipath, however, seems to have negligible impact on the efficacy of this spoofing detection system.</p>
<p>FIGURES 5 and 6 show the results of typical non-spoofed and spoofed cases from WSMR live-signal tests that took place on the evening of June 19–20, 2012. Each plot shows the spoofing detection statistic <em>γ</em> on the horizontal axis and various related probability density functions on the vertical axis. This statistic has been calculated using a modified test that includes the estimation of two additional unknowns: an antenna articulation scale factor <i>f</i> and a timing bias <i>t</i><sub>0</sub> for the decaying sinusoidal oscillation <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/eq-pa.jpg"><img class="alignnone  wp-image-21654" alt="eq-pa" src="http://www.gpsworld.com/wp-content/uploads/2013/06/eq-pa.jpg" width="224" height="25" /></a>. The damping ratio ζ and the undamped natural frequency <i>w</i><i><sub>n</sub></i> are known from prior system identification tests.</p>
<div id="attachment_21509" class="wp-caption alignnone" style="width: 610px"><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig5.jpg"><img class=" wp-image-21509 " alt="Figure 5. Spoofing detection statistic, threshold, and related probability density functions for a typical non-spoofed case with live data." src="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig5.jpg" width="600" height="378" /></a><p class="wp-caption-text">Figure 5. Spoofing detection statistic, threshold, and related probability density functions for a typical non-spoofed case with live data.</p></div>
<p>&nbsp;</p>
<div id="attachment_21510" class="wp-caption alignnone" style="width: 610px"><a href="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig6.jpg"><img class=" wp-image-21510 " alt="Figure 6. Performance of a typical spoofed case with live data: spoofing detection statistic, threshold, and related probability density functions." src="http://www.gpsworld.com/wp-content/uploads/2013/06/In-Fig6.jpg" width="600" height="400" /></a><p class="wp-caption-text">Figure 6. Performance of a typical spoofed case with live data: spoofing detection statistic, threshold, and related probability density functions.</p></div>
<p>The vertical dashed black line in each plot shows the actual value of <em>γ</em> as computed from the GPS data. There are three vertical dash-dotted magenta lines that lie almost on top of each other. They show the worst-case threshold values <em>γ</em><i><sub>th</sub></i> as computed for the optimal and ±2σ estimates of <i>t</i><sub>0</sub>: <i>t</i><sub>0<i>opt</i></sub>, <i>t</i><sub>0<i>opt</i></sub>+2σ<sub><i>t</i><sub>0<i>opt</i></sub></sub>, and <i>t</i><sub>0<i>opt</i></sub><i>-2σ<sub><i>t</i><sub>0<i>opt</i></sub></sub></i>. They have been calculated for a worst-case probability of false alarm equal to 10<sup>-6</sup>. An <i>ad hoc</i> method of compensating for the prototype system’s <i>t</i><sub>0</sub> uncertainty is to use the left-most vertical magenta line as the detection threshold <em>γ</em><i><sub><em></em>th</sub></i>. The vertical dashed black line lies very far to the right of all three vertical dash-dotted magenta lines in Figure 5, which indicates a successful determination that the signals are not being spoofed. In Figure 6, the situation is reversed. The vertical dashed black line lies well to the left of the three vertical dash-dotted magenta lines, and spoofing is correctly and convincingly detected.</p>
<p>These two figures also plot various relevant probability density functions. Consistent with the consideration of three possible values of the <i>t</i><sub>0</sub> motion timing estimate, these are plotted in triplets. The three dotted cyan probability density functions represent the worst-case non-spoofed situation, and the dash-dotted red probability functions represent the corresponding worst-case spoofed situations. Obviously, there is sufficient separation between these sets of probability density functions to yield a powerful detection test, as evidenced by the ability to draw the dash-dotted magenta detection thresholds in a way that clearly separates the red and cyan distributions. Further confirmation of good detection power is provided by the low worst-case probabilities of false alarm and missed detection, the latter metric being 1.6 ´ 10<sup>-6</sup> for the test in Figure 5 and 7 ´ 10<sup>-8</sup> for Figure 6.</p>
<p>The solid-blue distributions on the two plots correspond to the <em>η</em><i><sub>opt</sub></i> estimate and the spoofed assumption, which is somewhat meaningless for Figure 5, but meaningful for Figure 6. The dashed-green distributions are for the <a href="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg"><img class=" wp-image-21628 alignnone" alt="Eq-tra" src="http://www.gpsworld.com/wp-content/uploads/2013/06/Eq-tra.jpg" width="13" height="18" /></a> estimate under the non-spoofed assumption. The wide separations between the blue distributions and the green distributions in both figures clearly indicate that the worst-case false-alarm and missed-detection probabilities can be very conservative.</p>
<p>The detection test results in Figures 5 and 6 have been generated using the last full oscillation of the respective carrier-phase data, as in Figures 3 and 4, but applied to different data sets. In Figure 3, the last full oscillation starts at <i>t</i> = 3.43 seconds, and it starts at <i>t</i> = 2.11 seconds in Figure 4. The peak-to-peak amplitude of each last full oscillation ranged from 4-6 centimeters, and their periods were shorter than 0.5 seconds. It would have been possible to perform the detections using even shorter data spans had the mechanical oscillation frequency of the cantilevered antenna been higher.</p>
<p><b>Conclusions</b></p>
<p>In this article, we have presented a new method to detect spoofing of GNSS signals. It exploits the effects of intentional high-frequency antenna motion on the measured beat carrier phases of multiple GNSS signals. After detrending using a high-pass filter, the beat carrier-phase variations can be matched to models of the expected effects of the motion. The non-spoofed model predicts differing effects of the antenna motion for the different satellites, but the spoofed case yields identical effects due to a geometry in which all of the false signals originate from a single spoofer transmission antenna. Precise spoofing detection hypothesis tests have been developed by comparing the two models’ ability to fit the measured data.</p>
<p>This new GNSS spoofing detection technique has been evaluated using both Monte-Carlo simulation and live data. Its hypothesis test yields theoretical false-alarm probabilities and missed-detection probabilities on the order of 10<sup>-5</sup> or lower when working with typical numbers and geometries of available GPS signals and typical patch-antenna signal strengths. The required antenna articulation deflections are modest, on the order of 4-6 centimeters peak-to-peak, and detection intervals less than 0.5 seconds can suffice.</p>
<p>A set of live-signal tests at WSMR evaluated the new technique against a sophisticated receiver/spoofer, one that mimics all visible signals in a way that foils standard RAIM techniques. The new system correctly detected all of the attacks. These are the first known practical detections of live-signal attacks mounted against a civilian GNSS receiver by a dangerous new generation of spoofers.</p>
<p><b>Future Directions</b></p>
<p>This work represents one step in an on-going “Blue Team” effort to develop better defenses against new classes of GNSS spoofers. Planned future improvements include 1) the ability to use electronically synthesized antenna motion that eliminates the need for moving parts, 2) the re-acquisition of true signals after detection of spoofing, 3) the implementation of real-time prototypes using software radio techniques, and 4) the consideration of “Red-Team” counter-measures to this defense  and how the “Blue Team” could combat them; counter-measures such as high-frequency phase dithering of the spoofed signals or coordinated spoofing transmissions from multiple locations.</p>
<p><b>Acknowledgments</b></p>
<p>The authors thank the following people and organizations for their contributions to this effort:  The NASA Wallops Flight Facility provided access to their anechoic chamber. Robert Miceli, a Cornell graduate student, helped with data collection at that facility. Dr. John Merrill and the Department of Homeland Security arranged the live-signal spoofing tests. The U.S. Air Force 746th Test Squadron hosted the live-signal spoofing tests at White Sands Missile Range. Prof. Todd Humphreys and members of his University of Texas at Austin Radionavigation Laboratory provided live-signal spoofing broadcasts from their latest receiver/spoofer.</p>
<p><b>Manufacturers</b></p>
<p>The prototype spoofing detection data capture system used an <b>Antcom Corp.</b> (<i>www.antcom.com</i>) 2G1215A L1/L2 GPS antenna. It was connected to an <b>Ettus Research</b> (<i>www.ettus.com</i>) USRP (Universal Software Radio Peripheral) N200 that was equipped with the DBSRX2 daughterboard.</p>
<hr />
<p align="left"><em><b>MARK L. PSIAKI</b> is a professor in the Sibley School of Mechanical and Aerospace Engineering at Cornell University, Ithaca, New York. He received a B.A. in physics and M.A. and Ph.D. degrees in mechanical and aerospace engineering from Princeton University, Princeton, New Jersey. His research interests are in the areas of GNSS technology, applications, and integrity, spacecraft attitude and orbit determination, and general estimation, filtering, and detection.</em></p>
<p align="left"><em><b>STEVEN P. POWELL</b> is a senior engineer with the GPS and Ionospheric Studies Research Group in the Department of Electrical and Computer Engineering at Cornell University. He has M.S. and B.S. degrees in electrical engineering from Cornell University. He has been involved with the design, fabrication, testing, and launch activities of many scientific experiments that have flown on high altitude balloons, sounding rockets, and small satellites. He has designed ground-based and space-based custom GPS receiving systems primarily for scientific applications.</em></p>
<p align="left"><em><b>BRADY W. O’HANLON</b> is a graduate student in the School of Electrical and Computer Engineering at Cornell University. He received a B.S. in electrical and computer engineering from Cornell University. His interests are in the areas of GNSS technology and applications, GNSS security, and GNSS as a tool for space weather research.</em></p>
<h3>VIDEO</h3>
<p>Here is a video (in m4v format) of Cornell University&#8217;s antenna articulation system for the team&#8217;s first prototype spoofing detector tests.</p>
<p><iframe src="http://www.youtube.com/embed/78KGydgRDh0" height="315" width="420" allowfullscreen="" frameborder="0"></iframe></p>
<h3 align="left"><b>FURTHER READING</b></h3>
<p><b>• The Spoofing Threat and RAIM-Resistant Spoofers</b></p>
<p>“Status of Signal Authentication Activities within the GNSS Authentication and User Protection System Simulator (GAUPSS) Project” by O. Pozzobon, C. Sarto, A. Dalla Chiara, A. Pozzobon, G. Gamba, M. Crisci, and R.T. Ioannides, in <i>Proceedings of</i><i> </i><i>ION GNSS 2012</i>, the 25th International Technical Meeting of The Institute of Navigation, Nashville, Tennessee, September 18–21, 2012, pp. 2894-2900.</p>
<p>“<a href="http://www.gpsworld.com/defensesecurity-surveillanceassessing-spoofing-threat-3171/" target="_blank">Assessing the Spoofing Threat</a>” by T.E. Humphreys, P.M. Kintner, Jr., M.L. Psiaki, B.M. Ledvina, and B.W. O’Hanlon in <i>GPS World</i>, Vol. 20, No. 1, January 2009, pp. 28-38.</p>
<p><a href="http://www.navcen.uscg.gov/pdf/vulnerability_assess_2001.pdf" target="_blank"><i>Vulnerability Assessment of the Transportation Infrastructure Relying on the Global Positioning System – Final Report</i></a>. John A. Volpe National Transportation Systems Center, Cambridge, Massachusetts, August 29, 2001.</p>
<p>• <b>Moving-Antenna and Multi-Antenna Spoofing Detection</b></p>
<p><em>“</em>Robust Joint Multi-Antenna Spoofing Detection and Attitude Estimation by Direction Assisted Multiple Hypotheses RAIM<em>” by M. Meurer, A. Konovaltsev, M. Cuntz, and C. Hattich, in </em><i>Proceedings of</i><i> </i><i>ION GNSS 2012</i>, the 25th International Technical Meeting of The Institute of Navigation, Nashville, Tennessee, September 18–21, 2012,<em> pp. 3007-3016.</em></p>
<p>“GNSS Spoofing Detection for Single Antenna Handheld Receivers” by J. Nielsen, A. Broumandan, and G. Lachapelle in <i>Navigation</i>, Vol. 58, No. 4, Winter 2011, pp. 335-344.</p>
<p><em>• </em><b>Alternate Spoofing Detection Strategies</b></p>
<p>“Who’s Afraid of the Spoofer? GPS/GNSS Spoofing Detection via Automatic Gain Control (AGC)” by D.M. Akos, in <i>Navigation</i>, Vol. 59, No. 4, Winter 2012-2013, pp. 281-290.</p>
<p>“Civilian GPS Spoofing Detection based on Dual-Receiver Correlation of Military Signals” by M.L. Psiaki, B.W. O’Hanlon, J.A. Bhatti, D.P. Shepard, and T.E. Humphreys in <i>Proceedings of ION GNSS 2011</i>, the 24th International Technical Meeting of The Institute of Navigation, Portland, Oregon, September 19–23, 2011, pp. 2619-2645.</p>
<p>• <b>Statistical Hypothesis Testing</b></p>
<p><i>Fundamentals of Statistical Signal Processing, Volume II: Detection Theory</i> by S. Kay, published by Prentice Hall, Upper Saddle River, New Jersey,1998.</p>
<p><i>An Introduction to Signal Detection and Estimation</i> by H.V. Poor, 2nd edition, published by Springer-Verlag, New York, 1994.<b></b></p>
<p>Video (in m4v format) of Cornell University&#8217;s antenna articulation system for their first prototype spoofing detector tests.</p>
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		<title>Out in Front: Ruminations Upon  a Technical Program</title>
		<link>http://www.gpsworld.com/out-in-front-ruminations-upon-a-technical-program/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=out-in-front-ruminations-upon-a-technical-program</link>
		<comments>http://www.gpsworld.com/out-in-front-ruminations-upon-a-technical-program/#comments</comments>
		<pubDate>Sat, 01 Jun 2013 08:59:02 +0000</pubDate>
		<dc:creator>Alan Cameron</dc:creator>
				<category><![CDATA[Alan Cameron]]></category>
		<category><![CDATA[From the Editor]]></category>
		<category><![CDATA[Institute of Navigation]]></category>
		<category><![CDATA[ION GNSS]]></category>

		<guid isPermaLink="false">http://www.gpsworld.com/?p=21464</guid>
		<description><![CDATA[The Institute of Navigation’s (ION’s) advance program for the 2013 GNSS+ conference in September arrived in the mail the other day, and was avidly consumed. The technical sessions of this gathering are prime hunting ground for presentations that later become articles in this magazine, as are, to lesser extent, those of the European Navigation Conference, [...]]]></description>
				<content:encoded><![CDATA[<p>The Institute of Navigation’s (ION’s) advance program for the 2013 GNSS+ conference in September arrived in the mail the other day, and was avidly consumed. The technical sessions of this gathering are prime hunting ground for presentations that later become articles in this magazine, as are, to lesser extent, those of the European Navigation Conference, the Joint Navigation Conference, CTIA, ITS World Congress, and others.</p>
<p>Something struck me as I scanned the 280-odd presentations listed under 36 session tracks: the frequency with which the word BeiDou appeared. To determine if there were any substance to this fleeting impression, I essayed a quantitative analysis. Naturally, GPS and the generic GNSS occurred times beyond measure, but this is how the others fared.</p>
<p>IRNSS: 1<br />
QZSS: 3<br />
GLONASS: 10<br />
Galileo: 13<br />
BeiDou: 19.</p>
<p>What does this signify? Little enough, possibly. Still, something. A satellite navigation system bursts seemingly out of nowhere and within a few short years virtually laps the field, putting 20 (14 usable) transmitters into space and establishing a regional operating capability, soon to be global. That sort of thing tends to get noticed.</p>
<p>The titles of BeiDou-focused papers on tap this fall in Nashville — not all of them springing from the laptops of Chinese engineers, not by a long shot — add substance to this passing fancy.<br />
◾    BeiDou Consumer Receiver Chips at Last.<br />
◾    A Combined GPS/BeiDou Vector Tracking Algorithm for Ultra-tightly Coupled Navigation Systems.<br />
◾    Towards the Inclusion of Galileo and BeiDou/Compass Satellites in Trimble CenterPoint RTX.<br />
◾    New Assisted BeiDou Products from JPL’s Global Differential GPS System.<br />
◾    BeiDou Integration in Cell Phones and Tablets.<br />
◾    BeiDou — A System That is Now Ready for Applications.<br />
◾    Augmenting GPS RTK with Regional BeiDou in North America.<br />
◾    New Systems, New Signals, New Positions — Providing BeiDou Integration.</p>
<p>The affiliations of some of the authors of the above read like a top-level directory of North American and European GNSS manufacturers. Clearly, the ground has been plowed and the fields lie ready — if they are not already planted. Unless that’s too mixed a metaphor for satellite radionavigation signals.</p>
<p>The recent acquisition of one Western GNSS manufacturer by a major Chinese business concern has not gone unnoticed, either.<br />
For more intelligence, I consulted the newest member of this magazine’s Editorial Advisory Board. He replied to my emailed penny for his thoughts.</p>
<p>“I would be happy to contribute a column for the July issue based on my observations here at the China Satellite Navigation Conference in Wuhan. The article would be titled: Little Tigers versus Wolves.”</p>
<p>Wow. Now I wonder, who’s who?</p>
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		<title>The System: Galileo Leaves the Building</title>
		<link>http://www.gpsworld.com/the-system-galileo-leaves-the-building/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=the-system-galileo-leaves-the-building</link>
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		<pubDate>Sat, 01 Jun 2013 07:35:13 +0000</pubDate>
		<dc:creator>Alan Cameron</dc:creator>
				<category><![CDATA[Alan Cameron]]></category>
		<category><![CDATA[Galileo]]></category>
		<category><![CDATA[GLONASS]]></category>
		<category><![CDATA[GPS Modernization]]></category>
		<category><![CDATA[The System]]></category>
		<category><![CDATA[IRNSS]]></category>

		<guid isPermaLink="false">http://www.gpsworld.com/?p=21460</guid>
		<description><![CDATA[In the early hours of May 15, Galileo’s first full operational capability (FOC) satellite left manufacturer OHB System AG’s integration hall in Bremen, Germany, after successfully completing integration and system testing. Later that same day, it arrived by road at the European Space Agency’s (ESA’s) technical center at Noordwijk in the Netherlands for a rigorous [...]]]></description>
				<content:encoded><![CDATA[<p>In the early hours of May 15, Galileo’s first full operational capability (FOC) satellite<a href="http://www.gpsworld.com/first-galileo-foc-satellite-heads-to-testing/" target="_blank"> left manufacturer OHB System AG’s integration hall </a>in Bremen, Germany, after successfully completing integration and system testing. Later that same day, it arrived by road at the European Space Agency’s (ESA’s) technical center at Noordwijk in the Netherlands for a rigorous set of tests to check its readiness for launch. The tests will simulate different aspects of launch and space environment. The comprehensive test program will validate the new design and all the FOC satellites to follow.</p>
<p>This first FOC satellite is functionally identical to the first four in-orbit validation (IOV) satellites already in orbit, but has been built by a separate industrial team. Like the other 21 FOC satellites so far procured by ESA, the satellite’s prime contractor is OHB System AG, and the navigation payload was produced by Surrey Satellite Technology Ltd. in Guildford, UK.</p>
<p>Thermal vacuum testing at the European Space Research and Technology Centre (ESTEC) will simulate temperature extremes the satellites must endure in the airlessness of space throughout their 12-year working lifetimes. Without any moderating atmosphere, temperatures can shift hundreds of degrees from sunlight to shadow.</p>
<p>Other activities on the schedule include shaker and acoustic noise testing — simulating the vibration and noise of launch — as well as electromagnetic compatibility and antenna testing, placing the satellite in chambers shielded from all external radio signals to reproduce infinite space and check that its various antennas and electrical systems are interoperable without harmful interference.</p>
<p>“The Galileo FOC satellites provide the same capabilities as the previous IOV satellites, but with improved performance, such as higher transmit power,” explained Giuliano Gatti, the head of the Galileo Space Segment Procurement Office. “They are to all intents a new design that requires a full checkout before getting the green light for launch.”</p>
<p>The second FOC flight model is due to arrive at ESTEC in early June, and the third in the middle of July. The first two satellites are to be placed in orbit on board a Soyuz launcher, with a scheduled lift-off from Kourou in French Guyana this fall, with two more due to follow by the end of the year.</p>
<p>The first four Galileo IOV satellites, launched in 2011 and 2012, were provided by EADS Astrium with Thales Alenia Space Italy responsible for integrating the satellites and Astrium in Portsmouth, UK, providing the navigation payloads. They provided their first navigation fix in March 2013.</p>
<p>The definition, development and in-orbit validation phases of the Galileo programme are being carried out by ESA and co-funded with the European Commission (EC).</p>
<p>The subsequent FOC phase is managed and funded by the EC. The commission has delegated the role of design and procurement agent to ESA for the FOC phase. At the same time as the satellites are being assembled on a production-line basis, ground stations are also being established on European territories around the globe.</p>
<div id="attachment_21128" class="wp-caption alignnone" style="width: 563px"><a href="http://www.gpsworld.com/wp-content/uploads/2013/05/GPSIIF-7.jpg"><img class="wp-image-21128 " alt="Photo credit: Pat Corkery, United Launch Alliance." src="http://www.gpsworld.com/wp-content/uploads/2013/05/GPSIIF-7.jpg" width="553" height="368" /></a><p class="wp-caption-text">Photo credit: Pat Corkery, United Launch Alliance.</p></div>
<h3>GPS Leaves This Earth</h3>
<p>A t 5:38 p.m. Eastern Daylight Time (21:38 UTC) on May 15,  the fourth GPS IIF satellite, Space Vehicle Number (SVN) 66 built by Boeing, <a href="http://www.gpsworld.com/gps-iif-4-successfully-launched-from-cape-canaveral/" target="_blank">ascended towards orbit</a> aboard a United Launch Alliance Atlas V rocket at from Cape Canaveral Air Force Station, Florida.</p>
<p>“The GPS constellation remains healthy and continues to meet and exceed the performance standards to which the satellites were built. Our goal is to deliver sustained, reliable GPS capabilities to America’s warfighters, our allies, and civil users around the world, and this is done by maintaining GPS performance, fielding new capabilities and developing more robust modernized capabilities for the future,” said Colonel Bernie Gruber, director of the U.S. Air Force Space and Missile Systems Center’s GPS Directorate.</p>
<p>The new capabilities of the IIF satellites will provide greater navigational accuracy through improvements in atomic clock technology; a more robust signal for commercial aviation and safety-of-life applications, known as the new third civil signal (L5); and a 12-year design life providing long-term service. These upgrades deliver improved anti-jam capabilities for warfighters and improved security for military and civil users around the world, the Air Force said in a statement.</p>
<p>The IIF-4 satellite is expected to complete testing in August, after which it will be utilized as a reserve or backup satellite. It becomes the fourth satellite in a 12-strong network of GPS IIF spacecraft manufactured by Boeing as lead contractor, the first of which was boosted into orbit in May 2010. The Air Force expects the first of the next-generation GPS IIIA satellites to enter service sometime in 2014.</p>
<h3>System Briefs</h3>
<p><strong>GLONASS.</strong> The GLONASS 747 M-series satellite <a href="http://www.gpsworld.com/glonass-satellite-launched/" target="_blank">launched on April 26</a> has maneuvered into an orbital slot near GLONASS 728, the operational satellite in Plane 1, slot 2. 747 will presumably serve as a reserve until it replaces 728, unless another Plane 1 satellite expires first. The next Russian launch, a GLONASS-M trio, is scheduled for July 1. There are currently 24 operational GLONASS satellites.</p>
<p><strong>IRNSS.</strong> The first Indian Regional Navigation Satellite System satellite is <a href="http://www.gpsworld.com/resources/upcoming-gnss-satellite-launches/" target="_blank">expected to rise</a> at the end of June. The IRNSS plans to orbit of seven: three geostationary and four geosynchronous, providing regional coverage via navigation signals in the L5 and S bands.</p>
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		<title>Next-Gen GPS Ground Control System in Question</title>
		<link>http://www.gpsworld.com/next-gen-gps-ground-control-system-in-question/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=next-gen-gps-ground-control-system-in-question</link>
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		<pubDate>Thu, 30 May 2013 20:51:17 +0000</pubDate>
		<dc:creator>GPS World staff</dc:creator>
				<category><![CDATA[Alan Cameron]]></category>
		<category><![CDATA[Newsletter Editorials]]></category>
		<category><![CDATA[OCX]]></category>

		<guid isPermaLink="false">http://www.gpsworld.com/?p=21406</guid>
		<description><![CDATA[A March 2013 report from the Government Accountability Office (GAO) says the projected cost of the next-generation GPS ground-control system, known as OCX, increased by 43 percent, or $1 billion over the past year, to a total cost estimate of $3.7 billion. Design requirements for OCX call for it to support the GPS III constellation’s [...]]]></description>
				<content:encoded><![CDATA[<p>A March 2013 report from the Government Accountability Office (GAO) says the projected cost of the next-generation GPS ground-control system, known as OCX, increased by 43 percent, or $1 billion over the past year, to a total cost estimate of $3.7 billion. Design requirements for OCX call for it to support the GPS III constellation’s stringent accuracy, anti-jam, and information assurance requirements. The system is also to be backward-compatible with current GPS satellites.</p>
<p>Commented one knowledgeable source, “This is a very disturbing report and could spell the end for OCX. Although the GAO has some facts wrong, the basics are correct. Many of us have been pushing for an alternative, more capable, and much less costly system for years.”</p>
<p>Raytheon Intelligence and Information Systems won a $886.4 million prime contract to develop the OCX in February 2010, with an initial delivery date of 2016.</p>
<p>In December 2012, Col. Bernie Gruber of the U.S. Air Force GPS Directorate wrote in the pages of <i>GPS World</i> what was the commonly accepted perception of and public government position on OCX:</p>
<p>“Along with a host of additional satellite capabilities and signals, we will correspondingly modernize our ground segment. Our Next-Generation Operational Control System (OCX) is designed to command and control our modernized secondary civil signal L2C, safety-of-life signal L5, and the internationally compatible signal L1C.  . . . . . As the modernized signals become operational, users will see faster signal acquisition, enhanced reliability, and a greater operating range. The information assurance, expandability, and service-oriented architecture will afford users and operators with security and information they simply don’t have today.”</p>
<p><b>The View from 2013.</b> The 190-page GAO report, “Defense Acquisitions: Assessments of Selected Weapon Programs,” states that the scope and complexity of key OCX program elements was underestimated, and characterized the situation as typical of overruns that have historically beset Pentagon space programs.</p>
<p>Although the report (<a href="http://www.gao.gov/products/GAO-13-294SP" target="_blank">click here for highlights and to download the full PDF</a>) found that “The Department of Defense (DOD) 2012 portfolio of 86 major defense acquisition programs is estimated to cost a total of $1.6 trillion, reflecting decreases in both size and cost from the 2011 portfolio,” and that “Continuing a positive trend over the past four years, newer acquisition programs are demonstrating higher levels of knowledge at key decision points,” .</p>
<div id="attachment_21409" class="wp-caption alignright" style="width: 260px"><a href="http://www.gpsworld.com/wp-content/uploads/2013/05/sys_osx.jpg"><img class="size-thumbnail wp-image-21409" alt="The next-generation GPS ground-control system, known as OCX." src="http://www.gpsworld.com/wp-content/uploads/2013/05/sys_osx-250x142.jpg" width="250" height="142" /></a><p class="wp-caption-text">The next-generation GPS ground-control system, known as OCX.</p></div>
<p>Two of the 190 pages in the document specifically address OCX, which is identified as one of 19 weapons “Programs That Entered Development with Technologies Fully Mature or Nearing Maturity” and one of 14 “Programs with technologies nearing maturity at knowledge point 1 date.” OCX is given a knowledge point 1 date of November 2012.</p>
<p>According to the Report, “Air Force officials recently stated that, although GPS III is still maintaining an April 2014 &#8220;available for launch&#8221; date for the first satellite, the planned launch date is being moved to May 2015 in order to synchronize it with the availability of the GPS Operational Control Segment (OCX) Block 0, without which the satellites cannot be launched and checked out.”</p>
<p>“The program has experienced significant requirements instability and schedule delays while in technology development,” the report reads. “The contractor initially underestimated the scope and complexity of the necessary information assurance requirements which required additional personnel with the necessary expertise and increased government management.”</p>
<p><b>Changes in Specifications.</b> In June 2012, a Raytheon executive stated that the OCX contract had been significantly modified, with the addition of a launch and checkout capability that had previously been the responsibility of Boeing, prime contractor on the GPS IIF satellites.</p>
<p>He also identified information assurance, a primary OCX requirement, as “a big challenge. It is very important that we protect this system against the current and evolving cyber threats because they are real and the nation can’t afford to have this system compromised.”</p>
<p><b>An Update Last Autumn.</b> In a <a href="http://www.gpsworld.com/conversation-with-ray-kolibaba-on-the-gps-ground-control-segment/" target="_blank">November 2012 conversation </a>with <i>GPS World</i> defense editor Don Jewell, Raytheon <strong>V</strong>P and Program Manager for OCX Ray Kolibaba made the following remarks:<strong></strong></p>
<p><strong>“</strong>We currently have 450 people at Raytheon working OCX, and with our subs, an additional 300 personnel. Altogether we have 750 personnel working GPS and OCX issues. This does not include the military and civilian personnel at Air Force Space Command and Space and Missile Systems Center.”<strong><br />
</strong></p>
<p>[ . . . . ]</p>
<div id="attachment_13423" class="wp-caption alignright" style="width: 183px"><a href="http://www.gpsworld.com/wp-content/uploads/2012/11/Kolibaba-W.jpg"><img class="wp-image-13423 " alt="Kolibaba-W" src="http://www.gpsworld.com/wp-content/uploads/2012/11/Kolibaba-W.jpg" width="173" height="230" /></a><p class="wp-caption-text">Ray Kolibaba</p></div>
<p>“Basically we are nearly on cost for the OCX contract. The current contract value is $925M; the original cost estimate was $886M. We are driving forward on that and the Block 1 date or Ready to Operate (RTO) date. Right now, the customer team is working on finalizing a new enterprise schedule that will show the Program Management Directive dates. So, we don’t know the exact date the government envisions. I expect an official date either late this year or early next year. I encourage you to ask Colonel Gruber [U.S. Air Force GPS Directorate] this question, and maybe then we will also get an answer. We have given them our recommendations.</p>
<p>“Concerning sequestration, I am not worried. I believe we have a reasonable level of support from Congress to maintain and continue OCX. That doesn’t mean something won’t change. Our Washington folks tell us that OCX appears to be on solid footing. The Air Force FY13 Research, Development, Test &amp; Evaluation budget request for OCX, to include Raytheon, support contractors, the GPS Directorate, Federally Funded Research and Development Centers and the like, was $371.6M, and the Continuing Resolution amount was $369.4M — given the current budget environment, that is strong Congressional support.”</p>
<p>[ . . . . . ]</p>
<p>“Successful completion of OCX will make a huge difference on a number of fronts. For instance, even though the FAA and DOT don’t have a whole lot of funding to ante up, we are going to make a difference in how they operate in the future. Some actions are transparent, but not all, as we implement their requirements and as we move forward with OCX.</p>
<p>“The sooner we implement the true capabilities of GPS on airliners and stop adhering only to the fixed air routes, the sooner we will start saving time and money with a vastly more efficient and flexible air routing system.</p>
<p>“So, from the civil side, there is certainly a difference, and when we bring other signals in they will be key for us, such as L2C, L5, and L1C. We have the solutions to do that with our receivers at this point in time, and I think it is fairly low-risk. Indeed that is probably another of my unofficial milestones.</p>
<p>“[On] the navigation side, GPS accuracy will noticeably improve, and we will use a new Kalman Filter. We are working the new Kalman filter with ITT Exelis and JPL to enhance capabilities. Couple that with better information assurance, increased integrity and predictability, along with system safety, and you have many of the key differences in the OCS system going forward.</p>
<p>[  . . . . . . ]</p>
<p>“We are required to support 40 PRNs at a minimum, with growth potential to 63 PRNs, and we may be able to support more. I’m not sure there is a limit on the system as such.”</p>
<p>In April of this year, Don Jewell wrote in his <a href="http://www.gpsworld.com/the-29th-annual-national-space-symposium-better-every-year/" target="_blank">Defense PNT e-newsletter column</a>:</p>
<p>&#8220;Most readers [of the report] won’t take the time to [dig deep]  and will assume that the OCX program is grossly over budget. It is not. In fact, to reach that extraordinary number, OCX cost overruns would need to have grown by 43 percent for each year since it was awarded, and that is ludicrous. According to Raytheon VP and OCX Program Manager Ray Kolibaba, the $3.695 billion number probably comes from including “…programmatic costs beyond OCX development costs and pessimistic projections from the government” that in my experience no acquisition agency, nor Congress for that matter, would ever include when determining true program cost adherence parameters.</p>
<p>Jewell makes the further point that OCX has grown in scope and schedule due in part to government change requests, mainly in the cyber and information assurance areas.</p>
<p><b>Where It Stands Now.</b> Notwithstanding the optimism of the Raytheon OCX program manager six months ago, it is reasonable to expect that the GAO estimate of increased cost has drawn Congressional attention, and that in the current fiscal climate, the entire program may once again be imperiled.</p>
<p>&nbsp;</p>
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		<title>CTIA: Automakers Developing Their Own Infotainment Apps</title>
		<link>http://www.gpsworld.com/ctia-automakers-developing-their-own-infotainment-apps/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=ctia-automakers-developing-their-own-infotainment-apps</link>
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		<pubDate>Tue, 28 May 2013 20:13:33 +0000</pubDate>
		<dc:creator>Janice Partyka</dc:creator>
				<category><![CDATA[Janice Partyka]]></category>
		<category><![CDATA[Newsletter Editorials]]></category>
		<category><![CDATA[Transportation Opinions]]></category>
		<category><![CDATA[Wireless Pulse]]></category>
		<category><![CDATA[CTIA]]></category>
		<category><![CDATA[GM]]></category>
		<category><![CDATA[OnStar]]></category>

		<guid isPermaLink="false">http://www.gpsworld.com/?p=21334</guid>
		<description><![CDATA[By Janice Partyka It’s a trifecta. The most interesting news at CES, Mobile World Congress, and now CTIA was the connected vehicle. Last week at CTIA, the biggest mobile conference in the U.S., GM and OnStar demonstrated ideas of what we can expect in vehicles once AT&#38;T&#8217;s LTE network makes its way into vehicles. We [...]]]></description>
				<content:encoded><![CDATA[<p><em><a href="http://www.gpsworld.com/wp-content/uploads/2013/05/OnStar_logo-T.jpg"><img class="size-full wp-image-21335 alignright" alt="OnStar_logo-T" src="http://www.gpsworld.com/wp-content/uploads/2013/05/OnStar_logo-T.jpg" width="150" height="73" /></a>By Janice Partyka</em></p>
<p>It’s a trifecta. The most interesting news at CES, Mobile World Congress, and now <a href="http://www.ctia.org/" target="_blank">CTIA</a> was the connected vehicle. Last week at CTIA, the biggest mobile conference in the U.S., GM and OnStar demonstrated ideas of what we can expect in vehicles once AT&amp;T&#8217;s LTE network makes its way into vehicles. We heard about many of their concepts in February at Mobile World, but with the infotainment possibilities being shown at CTIA, it is clear the endeavor is evolving quickly. Providers of navigation, mapping, traffic, middleware, search, points of interest and mobile advertising have key roles. We’ll check in ahead with some of these companies.</p>
<p>GM and OnStar envision an in-vehicle curated app ecosystem with downloadable apps and remote vehicle management. Developers will have access to APIs that can access the vehicle’s speed, performance, GPS, fuel economy and other information, but are kept out of areas that could cause safety issues. GM, as well as other OEMs, is not ready to let the app marketplace take money out of its pocket. The automaker is pushing to get apps built specially for its vehicles. Mary Chan of GM said that the business model hasn’t been decided, but the apps may be free, bundled into a service that GM charges for, or paid out to the developers. Another possibility is an app subscription paid for on a smartphone could be applied to a separate app in the car. We have to wait until model year 2015 to see it come off the assembly line.</p>
<p>Snippets heard at CTIA:</p>
<p style="padding-left: 30px;">“The biggest challenge of indoor location is having a good enough return on investment by the venue.” <i>Derek Peterson, Boingo</i></p>
<p style="padding-left: 30px;">“We hear many pitches from companies that want to supply us with indoor location technology, but so many of them are just unscalable.” <i>David Hildebrandt, ATT</i></p>
<p style="padding-left: 30px;">“Relevant, connected car data trumps free.” <em>Mary Chan, General Motors</em></p>
<p style="padding-left: 30px;">“The future killer mobile apps are banking, retail, medical (records, diagnosis) and government (voting, administrative).” <em>Michael Saylor, MircoStrategy</em></p>
<p style="padding-left: 30px;">“The ownership of data in connected cars will be a huge issue. And what happens to data in a vehicle when you transfer ownership?” <em>Mary Chan, General Motors</em></p>
<p><b>Traffic Information Is Getting Better.</b> Traffic information is getting more granular, hence more useful. INRIX and others are collecting traffic data in road segments about 250 meters long, a significant improvement from the past. Not too long ago, traffic data was provided solely by sensors, cameras and helicopters, which covered only highways and some arterial roads. The use of crowd-sourced traffic data now provides a leap in the amount of traffic data collected, enabling more current traffic conditions, as well more roads, to be monitored. “We can collect traffic data for these small road segments from all sources, crunch it and turn it around in under a minute,” says Bill Schwebel of INRIX.</p>
<p><b>How Fast?</b> In a few years, Schwebel says we will see an expansion of navigation that goes beyond driving from point A to point B. This would include accurate estimates of the entire length of your trip, for instance, driving from your home to arriving at your airport gate. “We will be getting more feeds from parking lots with electronic counters, but we can also see the dwell time in a parking lot, or cars that exit without parking, all from crowdsourcing,” adds Schwebel. Waits at TSA lines or rental car counters can be devised using historical and near real-time data. When schedules of events in the area and school calendars are added, the predictions get better.</p>
<p><b>Navigation Changes Ahead.</b> Turn-by-turn navigation will take a step forward to becoming more interactive when it becomes a two-way broadcast. Niall Berkery of Telenav, predicts that two-way connected navigation will appear in 2014-2016. “We are now focused on reducing the complexity of navigation and making it more personalized,” says Berkery. The entire industry, hindered by the perspective that navigation is free, is focusing on adding value. Telenav acquired ThinkNear to add hyperlocal marketing to its offering.</p>
<p><b>Embedded Navigation and the Delivery Man.</b> Berkery estimates that 30% of navigation systems are embedded in the vehicle, which can makes updating or servicing the devices challenging. Some years ago an interesting solution was developed in China. When an embedded navigation system needed servicing, it was handled by a package delivery service, similar to FedEx. The delivery person manually removed the navigation hard drive from a consumer’s vehicle and sent it off to be fixed or replaced. When the drive came back from the factory, the package delivery person reinstalled it. That’s pretty special service.</p>
<p>If you missed last week’s CTIA show, held May 21-23 in Las Vegas, you will have to wait a year and a half for its next appearance. With CES and the Mobile World Congress positioned on the calendar prior to CTIA, the other shows drew the lion’s share of product announcements and crowds. CTIA will reposition itself in front of these competing shows. CTIA’s new “Super Mobility Week” will be more international and take the place of the current fall and spring CTIA shows. Super Mobility Week will be held Sept 9-11, 2014 in Las Vegas and will include MobileCON and other major partnerships to create a bigger show experience.</p>
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		<title>Google and Facebook Eye Waze as Potential Purchase</title>
		<link>http://www.gpsworld.com/google-and-facebook-eye-waze-as-potential-purchase/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=google-and-facebook-eye-waze-as-potential-purchase</link>
		<comments>http://www.gpsworld.com/google-and-facebook-eye-waze-as-potential-purchase/#comments</comments>
		<pubDate>Tue, 28 May 2013 20:04:03 +0000</pubDate>
		<dc:creator>Kevin Dennehy</dc:creator>
				<category><![CDATA[Kevin Dennehy]]></category>
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		<category><![CDATA[Waze]]></category>

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		<description><![CDATA[Since the recent CTIA conference wasn’t the buffet of location news, one potential deal could really set the industry on fire going into the summer months. Google and Facebook both are rumored to be in talks to purchase Waze. Some say this would mean Facebook would transform into a mobile advertising company, with local ads, [...]]]></description>
				<content:encoded><![CDATA[<p><strong><a href="http://www.gpsworld.com/wp-content/uploads/2013/05/waze_logo.jpg"><img class=" wp-image-21326 alignright" alt="waze_logo" src="http://www.gpsworld.com/wp-content/uploads/2013/05/waze_logo.jpg" width="240" height="240" /></a>Since the recent CTIA conference wasn’t the buffet of location news, one potential deal could really set the industry on fire going into the summer months. Google and Facebook both are rumored to be in talks to purchase <a href="http://www.waze.com/" target="_blank">Waze</a>. Some say this would mean Facebook would transform into a mobile advertising company, with local ads, if it were the winning bidder. Google’s rumored interest would block the social media giant’s momentum in that marketplace.</strong></p>
<p><em>by Kevin Dennehy</em></p>
<p>In what could be one of biggest deals in the location industry, both Google and Facebook have been rumored to be interested in buying Israel-based mapping and navigation company Waze. Published reports indicate the deal could be worth $1 billion.</p>
<p>Some industry analysts are skeptical that a deal could be valued that high, which would place it in the same realm as Facebook’s $1 billion purchase of photo-sharing service Instagram.</p>
<p>“We really do not know if Facebook is willing to spend a billion dollars on Waze, but if the deal happens, (Facebook) must have considered its options. How could this be? First, I suspect that Facebook is certain it will grow beyond its current boundaries to become the world’s most valuable company,” said Mike Dobson, <a href="http://blog.telemapics.com" target="_blank">Telemapics</a> president. “Operating under this mindset, a billion dollars is peanuts, and they will not care if everyone else thinks they overpaid. In other words, Facebook might not be basing its calculation on the same ‘time-value of money’ that the rest of us are using. Second, if the economics do not really matter to Facebook, the more important question is ‘What advantages would Facebook accrue by acquiring Waze?’”</p>
<p>Dobson believes that Waze map databases are not competitive with Google or such commercial providers as Nokia or TomTom. “In essence, Waze does not offer competitive map coverage, competitive data quality, competitive data attributing, or a useful source of POI data. More importantly, I suspect that the Waze database will be a major league headache if Facebook plans to use it as the basis for its mapping activities supporting local search,” he said. “Further, I doubt that Waze understands enough about local advertising to help Facebook realize its most important goal of becoming a powerhouse ad agency capable of creating its own captive local search market, comparable or exceeding that enjoyed by Google.”</p>
<p>Another industry insider, Marc Prioleau of Prioleau Advisors, said that quality and coverage of the maps would make the deal successful — if it really is going to happen. &#8220;The rumor mill on Waze seems to be quite active so it is hard to know if there is substance there. Waze has built a very innovative traffic application, and they use the user data to build a digital map data set,” he said. “The value of the company would be tied largely to the quality and coverage of that data set and the perceived ability of a big platform like Facebook to build that out into a truly serviceable worldwide map.&#8221;</p>
<p>Waze is a mapping company built through crowdsourcing map and traffic data over mobile phones, which is the “magic” Dobson believes Facebook finds beguiling about the company.  While Waze claims 45 million users, its active base is more likely around 10-15 million, Dobson said. “Conversely, if you stop to consider the amount of data you could generate if all of Facebook’s mobile users were gathering mapping data through an app built on Waze, then the company might be willing to gamble on the acquisition,” he said. “Providing analytics on the behavior and location of its mobile users to advertisers and other interested parties could be a huge opportunity. On the other hand, there are numerous paths to this endpoint, not just Waze.”</p>
<p>Dobson said if he were to advise Facebook on the acquisition, a suggested course of action would be that the company write their own crowdsourcing application and build a good quality map database through licensing and direct and indirect map compilation techniques.  “My off-the-cuff estimate is that this could be done for less than the cost of the Waze acquisition. Beating Waze into a quality map database is going to be an expensive — well beyond the acquisition cost — and time consuming effort. Perhaps the most glaring lack in the potential Waze acquisition is the absence of a suitable POI database, which, in my opinion, is the most critical need that Facebook will have in local search.”</p>
<p>Dobson said he suspects that Facebook’s competitors are not concerned about the company’s potential acquisition of Waze. “Those who already in the mapping business — Google and Apple — will anticipate that it is likely that Waze could become a significant distraction for Facebook and delay the company effectively competing in the local search market. As far as the competitors are concerned, the longer it takes Facebook to mobilize its efforts in local search, the better,” he said. “In business, as in life, strange choices are made. Perhaps Facebook sees a future in Waze that depends on strategies being implemented by the company that we know nothing about. I hope so, as a good dose of innovation is just what the local search market needs.”</p>
<p>Distinguishing itself is another reason Facebook may be interested in Waze. Providing mapping and traffic capabilities may bring more consumers to its mobile users.</p>
<p>The company is also is redesigning its mobile pages platform to enable local merchant information, according to published reports. These new improvements may even challenge <a href="https://foursquare.com/" target="_blank">Foursquare</a> and <a href="http://www.yelp.com" target="_blank">Yelp</a>.</p>
<p>There were questions whether the deal with Facebook will go through as published reports indicated that Waze’s research and development activities would remain in Israel rather than go to California, where Facebook’s headquarters are based.</p>
<p><b>Google Interested in Waze to Cut off Facebook at the Location Pass?</b></p>
<p>The rumor mill is heating up as Internet giant Google and Apple are said to also be interested in Waze.  “I saw a report indicating that Google was interested. If so, it would seem that this would be a move to deny Facebook access to Waze,” Dobson said.  “Google already derives a significant amount of information from passive crowdsourcing — recording the GPS traces of the devices of their users — and I am not sure that the acquisition would provide them any opportunities that they are not already exploiting. Of course, we might remember that Garmin, who had no intention of buying TeleAtlas, made a bid and significantly raised the price that TomTom paid for the mapping company.”</p>
<p>Other analysts say while there have been several news articles on why Google should buy Waze, it all could be poorly informed speculation. Others say that the Israel tech press is quick to spread rumors. One analyst said, “I hear that the talks are legit, but my guess is that the deal in discussion is not $1 billion.”</p>
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		<title>TeleCommunication System Next Gen 911 First in Production with Carriers</title>
		<link>http://www.gpsworld.com/telecommunication-system-next-gen-911-first-in-production-with-carriers/?utm_source=rss&#038;utm_medium=rss&#038;utm_campaign=telecommunication-system-next-gen-911-first-in-production-with-carriers</link>
		<comments>http://www.gpsworld.com/telecommunication-system-next-gen-911-first-in-production-with-carriers/#comments</comments>
		<pubDate>Tue, 28 May 2013 19:10:58 +0000</pubDate>
		<dc:creator>Janice Partyka</dc:creator>
				<category><![CDATA[Government News]]></category>
		<category><![CDATA[Janice Partyka]]></category>
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		<category><![CDATA[Public Safety]]></category>
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		<category><![CDATA[E911]]></category>
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		<description><![CDATA[TeleCommunication Systems (TCS), a provider of mobile communication technology, announced that its TCS VoLTE9-1-1 service is first into production with Tier-1 wireless carriers, including two of the largest North American operators. The fully customizable solution enables 4G/LTE carriers to provide both 911 call routing and originating coarse/precise location information, including the 10-digit callback number, to [...]]]></description>
				<content:encoded><![CDATA[<p><a href="http://www.telecomsys.com/" target="_blank">TeleCommunication Systems (TCS)</a>, a provider of mobile communication technology, announced that its <a href="http://http://www.telecomsys.com/products/public-safety/VoLTE911.aspx" target="_blank">TCS VoLTE9-1-1</a> service is first into production with Tier-1 wireless carriers, including two of the largest North American operators. The fully customizable solution enables 4G/LTE carriers to provide both 911 call routing and originating coarse/precise location information, including the 10-digit callback number, to public safety access points (PSAPs).</p>
<p>Initially, wireless carriers deployed 4G/LTE solely for data use. Without VoLTE9-1-1 capabilities, carriers must process emergency calls over 3G networks (circuit-switched fallback), even in areas where LTE is deployed. However, with TCS&#8217; VoLTE9-1-1 service, they can now process 911 calls in an all-LTE environment, enabling them to reclaim or reuse 3G spectrum.</p>
<p>&#8220;As carriers increasingly move toward LTE networks, the ability to handle 911 emergency communications is critical,” said Thomas Ginter of TCS. “By leveraging VoLTE9-1-1, network operators are helping to ensure subscribers receive the responsiveness they need in an emergency situation, while expanding coverage to areas where 3G coverage is lacking.”</p>
<p>TCS VoLTE9-1-1 features:</p>
<ul>
<li><b>Call routing to the PSAP:</b> The TCS VoLTE9-1-1 service routes a 4G/LTE-originated 911 call using coarse location via the route determination function component.</li>
<li><b>PSAP telecommunicators can call back if disconnected:</b> The TCS VoLTE9-1-1 service remains fully backwards compatible, supporting necessary functions such as providing PSAPs with full 10-digit subscriber callback numbers.</li>
<li><b>Re-bid by a PSAP for precise location after call routing:</b> The location retrieval function allows a wireless carrier complete flexibility in choosing its underlying high-accuracy location technology and supports updated/precise position requests.</li>
<li><b>Emergency voice call continuity for location service:</b> Location continuity and location delivery to the PSAPs are supported in usage scenarios where the 911 call switches from 4G/LTE to 3G/2G networks.</li>
<li><b>Expansion beyond voice:</b> As wireless networks advance, multimedia objects such as text, audio and video can be transferred to a compatible termination point with LTE IP networks, for example, an NG ESINet and i3 PSAP. Leveraging an all-IP network makes it easier and more cost effective to interconnect services.</li>
<li><b>Small cell support: </b>The TCS VoLTE9-1-1 solution supports small cells, including femtocells, microcells, and picocells, which are now commonly used in dense urban, indoor areas and enterprise networks.</li>
</ul>
<p>TCS supports half of all U.S. wireless E911 calls, serving more than 140 million wireless and IP-enabled devices.  The company holds more than 280 patents, 43 of which relate to public safety, and more than 360 pending worldwide.</p>
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