Let’s all remember, brevity is the soul of wit.

GPS III Flexible Signal Generator. With completion of the Delta Preliminary Design Review for the GPS III satellites, Lockheed Martin and the U.S. Air Force announced that “an innovative new waveform generator permits the addition of new navigation signals after launch to upgrade the constellation without the need to launch new satellites.”

IGS Real-Time Service. The International GNSS Service, a worldwide federation of agencies involved in high-­precision GNSS applications, announced the launch of its Real-­Time Service (RTS). The RTS is a global-scale GNSS orbit and clock correction service that enables real-time precise point positioning and related applications requiring access to IGS low-latency products. The RTS is offered in beta as a GPS-­only service for the development and testing of applications.

QZSS Will Grow to Four. The Japanese government has ordered three navigation satellites from Mitsubishi Electric Corp. to expand the Quasi-Zenith Satellite System, currently orbiting the sole Michibiki. QZSS augments GPS navigation signals for users in the Asia-Pacific region. NEC Corporation has been awarded a contract for the QZSS ground control segment.

Real-Time PPP with Galileo. Fugro Seastar AS achieved this task within a week of all four Galileo satellites being activated. Fugro is now generating Galileo orbit and clock corrections, which can be used in conjunction with the Fugro G2 decimeter-level corrections associated with its GPS/GLONASS PPP service.

BeiDou Ground System Approved. The BeiDou Ground-Based Enhancement System (BGBES), a network of 30 ground stations, an operating system, and a precision positioning system, was approved by a Chinese government evaluation committee. The system is expected to improve BDS positioning accuracy to 2 centimeters horizontal and 5 centimeters vertical via tri-band real-time precision positioning technology, and to 1.5 meters with single-frequency differential navigation technology.

CNAV Test on GPS L2C and L5. The U.S. Air Force Space Command announced that CNAV capabilities on the GPS L2C and L5 signals will be tested in June. The civilian navigation message to be carried by modernized GPS will have similar data to the existing NAV message, but its structure will be different, with increased message bandwidth for greater information density. L2C and L5 users and receiver manufacturers are encouraged to review the test plan, provide comments, and participate in the evaluation process.

GPS at the Smithsonian. Brad Parkinson’s presentation, “GPS for Humanity — The Stealth Utility,” is now available as video on UStream.The talk helped introduce the new Smithsonian National Air and Space Museum exhibit, “Time and Navigation: The Untold Story of Getting from Here to There,” which is now open and free to the public in Washington, D.C.

Measurements of individual Galileo horizontal position fixes performed for the first time using the four Galileo satellites in orbit plus the worldwide ground system between 1000 and 11:00 CET on Tuesday 12 March 2013, showing an overall horizontal accuracy over ESTEC in Noordwijk, the Netherlands, of 6.3 m.

Galileo Logs First Autonomous Fix; Galileo over Canada (By James T. Curran, Mark Petovello, and Gérard Lachapelle); and Indoor Nav: Early Steps towards FCC Standards

Galileo Logs First Autonomous Fix

Entitling its release “From Orbit with Love,” the European Space Agency (ESA) announced March 12 that the four current satellites of the Galileo constellation achieved their first autonomous position fix. The feat was replicated by the NavSAS group of Politecnico di Torino, by GNSS manufacturer Septentrio, and by a University of Calgrary team as the four satellites appeared over North America.

The obtained accuracy lies in the 10-meter range, according to ESA, adding that this fulfills expectations, considering the infrastructure is only partly deployed. The fix was obtained by ESA’s Netherlands navigation lab, using the four satellites, launched in October 2011 and 2012, and the Galileo programme’s ground infrastructure: control centers in Italy and Germany and a global network of ground stations.

With only four satellites for the time being, the full Galileo constellation is visible at the same time for a maximum two to three hours daily. This frequency will increase as more satellites join the constellation in orbit, along with extra ground stations coming online, for Galileo’s early services to start at the end of 2014.

With the validation testing activities under way, users might experience breaks in the content of the navigation messages being broadcast, said ESA. In the coming months the messages will be further elaborated to define the offset between Galileo System Time and Coordinated Universal Time (UTC), enabling Galileo to be relied on for precision timing applications, as well as the Galileo to GPS Time Offset, ensuring interoperability with GPS.

NavSAS Confirmation. Almost simultaneously with the ESA announcement, the NavSAS group of Politecnico di Torino and Istituto Superiore Mario Boella in Turin, Italy, also achieved a position fix using the signals of the four In-Orbit Validation satellites (PFM, FM2, FM3, FM4). NavSAS researchers computed the positions using full software receivers developed by the team.

Septentrio, Too. Septentrio became the first receiver manufacturer to report an autonomous real-time position calculation using Galileo IOV satellites with its own standard commercial receiver. The company based in Leuven, Belgium announced on March 12 that it performed  standalone position calculated from in-orbit navigation messages using a standard PolaRx4 GNSS receiver equipped with commercially released firmware.

This achievement was followed by a further Septentrio release stating performance of what it believes to be the first 4-constellation PVT by a standard commercial receiver, on March 12 at approximately 10:35 UTC.

The milestone in all three accounts is that it is Galileo-only real-time positioning. Galileo positioning in post-processing mode was described by authors from the Technische Universität München and the German Space Operations Center, in a GPS World account, February 2012 issue.

Galileo over Canada

By James T. Curran, Mark Petovello, and Gérard Lachapelle

Within a day of activation over Europe, Galileo satellites were visible over North America. The PLAN Group of the University of Calgary captured and processed signals from Galileo PRN 11, 12, and 19 on E1B/C. The PLAN software GSNRx  simultaneously tracked GPS L1 and GLONASS L1 for combined solutions in real time.

The Galileo navigation message on E1B stated that the satellite health status is flagged as E1BHS=3 meaning “Signal Component currently in Test” and the data validity status is flagged as E1BDVS=1 meaning “Working without guarantee.” Current Galileo-ready commercial receivers may automatically discard measurements from a satellites broadcasting such messages. Parsing the received words in the I/NAV message, more than 50 percent were of type 0, although all words (types 0 to 10) were decoded at some point during the test.

Figure 1. 2D position errors.

Data was collected using a roof-mounted NovAtel 702GG antenna and an in-house two-channel digitizing front-end clocked by a high quality OCXO, in addition to a three-channel National Instruments front-end for post-processing. The two-channel intermediate frequency data was streamed live to a laptop computer for real-time processing with GSNRx. The GPS and GLONASS signals were tracked using a Kalman-filter-based tracking strategy while the Galileo signals were tracked using a specialized data-pilot algorithm.

Pseudorange and Doppler observations were extracted from the tracking strategies at a rate of 2 Hz. Single-frequency single-point position solutions were then computed for each of the three systems, each of the three pairs of systems and for the full combined Galileo-GLONASS-GPS. In the case of the three-satellite Galileo solution, the height was held fixed. Figure 1 shows 2D position errors with respect to antenna ITRF coordinates. Departures of the solutions involving GLONASS are likely due to orbital biases, given location of Calgary with respect to GLONASS ground stations.

Figure 2. Pseudorange residuals.

Next, by fixing the known position in the solution and solving only for the three clock biases, accurate pseudorange residuals were computed and are shown Figure 2. Galileo PRN 19, launched a year later than PRN 11 and 12, exhibits larger residuals, perhaps attributable to ephemeris or orbital errors. The overall results show very good consistency of the Galileo results and the PLAN Group equipment and GSNRx receiver.

Indoor Nav: Early Steps towards FCC Standards

The Federal Communications Commission (FCC) on March 14 released two reports from its Communications Security, Reliability, and Interoperability Council (CSRIC): the “Indoor Location Test Bed Report,” and “Leveraging LBS and Emerging Location Technologies for Indoor Wireless E9-1-1.”
They report on Bay Area tests of technology from NextNav, Polaris Wireless, and Qualcomm, in four representative morphologies (dense urban, urban, suburban, rural) and various building types. They are available online, via www.gpsworld.com/csric, are the subject of an Expert Advice column (see page 10), and will be more fully discussed in May issue.  For now, this summary from the first-named report:

“Seven location vendors/technologies began the process to demonstrate their performance indoors through the common test bed, but only three completed the process. Of these three, two technologies (AGPS/AFLT and RF Fingerprinting) are already in common use for emergency services, while the third (metropolitan beacons) is not yet commercially available. However all technologies tested demonstrated relativity high yield and various levels of accuracy in indoor environments.

“Significant standards work is required for practical implementation of many emerging location technologies for emergency services use.

“Many positioning methods require handset modifications. Integration of these modified handsets into the subscriber base, once the location technology is commercially available, will take years to complete.

“Progress has been made in the ability to achieve significantly improved search rings in both a horizontal and vertical dimension. However, even the best location technologies tested have not proven the ability to consistently identify the specific building and floor, which represents the required performance to meet Public Safety’s expressed needs. This is not likely to change over the next 12–24 months. Various technologies have projected improved performance in the future, but none of those claims have yet been proven through the test bed process. It is hoped that such technologies would be tested and validated in future test bed campaigns.”

An April 16 GPS World Webinar covers this topic with test participants. Registration is free.

New Organization Advocates for GPS Industry; Galileo Lives to Fly Another Day, Budget Passed; Safer Skies for EGNOS; and GLONASS in Brazil

New Organization Advocates for GPS Industry

A new group, the GPS Innovation Alliance, has formed and announced itself as the voice of the U.S. GPS industry and community of users, to “support the ever-increasing importance of GPS” in the U.S. capital, Washington, D.C.  The organization subsumes and replaces both the U.S. GPS Industry Council, an entity of longstanding, and the Coalition to Save Our GPS, which arose in March 2011 in response to a Federal Communications Commission (FCC) conditional waiver granted to LightSquared.

The alliance appears to reflect a desire on the part of some industry members to take a more aggressive approach inside the Washington Beltway, a sign, it would seem, of the political times. Some of those involved spoke informally of a desire to take advantage of contacts made on Capitol Hill and in the media during the highly visible LightSquared combat, fought in the glare of media attention heretofore unknown in industry circles.

Members of the Alliance are drawn from a variety of fields and businesses reliant on GPS, as well as leading manufacturers of GPS equipment. The former group includes, aviation, agriculture, construction, transportation, first responders, and surveying and mapping, and consumer organizations representing users of GPS for boating and other outdoor activities, and in automobiles, smartphones, and tablets.

Joining John Deere, Garmin, and Trimble — three lead drivers of the Coalition effort at the FCC — are NovAtel Inc. and Topcon Positioning Systems. All five were previously long-time members of the USGIC, and they appear as founding members of the alliance at www.gpsalliance.org.

Affiliate members listed on the website include the Association of Equipment Manufacturers, General Aviation Manufacturers Association, National Association of Manufacturers, Association for Unmanned Aerial Vehicles International, and Boat Owners Association of the United States.

The alliance plans to build on “the proud heritage and extensive expertise of the United States GPS Industry Council (USGIC), which was formed in 1991 to promote broader commercial applications of GPS and to expand global markets while assisting in safeguarding the technology’s military advantages. The council has a long history of highly effective advocacy on behalf of the GPS industry, as well as serving as a trusted source of objective information for policy makers, the media and the public both in the U.S. and around the world.” The alliance website gives a longer statement about the history and record of the USGIC, highlighting its role in international negotiations.

Michael Swiek, executive director of the USGIC, has transitioned to become the executive director, executive branch and international, of the Innovation Alliance. In addition to working closely with leading offices of executive branch departments of the U.S. government, he will continue well-established dialogs with governmental, private sector and academic entities in areas critical to GPS and satellite navigation among key players in Europe, Japan, Russia, Korea, China, and elsewhere.

Heather Hennessey, a principal of Innovative Federal Strategies LLC, a “comprehensive government relations firm,” has taken the position of executive director, legislative, at the alliance. Hennessey has seven years of service in the House of Representatives, including two years as chief of staff for Congressman Jack Kingston of Georgia.

An active voice in alliance representations on Capitol Hill will presumably be that of Jim Kirkland, vice president and general counsel for Trimble. Kirkland was the most prominent spokesperson for the coalition during the LightSquared battle, which appears to be either over or nearly so. “The alliance is committed to ensuring constructive, robust dialog between GPS users, manufacturers and policy makers on critical policy issues affecting GPS,” Kirkland said, “a commitment Trimble is pleased to be a part of as the industry continues to innovate and modernize.”

The alliance mission statement cites the importance of GPS to global economy and infrastructure; vows to aid further GPS innovation, creativity and entrepreneurship; and to protect, promote and enhance the use of GPS.

The GPS Innovation Alliance officially launched on February 13 with a reception on Capitol Hill, a traditional lobbying tactic that previous efforts had perhaps not envisioned.  The organization has also hired a public relations firm, Prism Public Affairs, and commissioned a logo.

Galileo Lives to Fly Another Day, Budget Passed

BeiDou ICD: Signal Specs Are Free At Last

The interface control document (ICD) describing the details of the BeiDou B1I open service signal on 1561.098 MHz was released December 27 at a news conference held in Beijing by the Chinese State Council Information Office. The ICD includes details of the navigation message, parameters of the satellite almanacs, and ephemerides that did not appear an earlier, incomplete version of the ICD released at the end of 2011.

An English version is available for download courtesy of the University of New Brunswick. The ICD specifies the relations of the signal in space interface between BeiDou Navigation Satellite System and users’ terminal receivers. It is the essential technical document to develop and make receivers and chips.

Anyone who has questions about the ICD is invited to submit them to BeiDouICD@beidou.gov.cn.

The document, BeiDou Navigation Satellite System Signal In Space Interface Control Document — Open Service Signal B1I (Version 1.0), includes a system introduction, signal standards and navigation message, which defines the related contents of the open-service signal B1I between the BeiDou Navigation Satellite System and users’ terminals.

In a previous presentation given at the Seventh Meeting of the International Committee on Global Navigation Satellite Systems (ICG)  in November, 2012, BeiDou officials stated that by 2020 there will be five GEO and 30 non-GEO satellites. The number of IGSO and MEO satellites was not specified, but previous presentations have said three IGSOs and 27 MEOs. These numbers are also stated in the official ICD.

“The GEO satellites are operating in orbit at an altitude of 35,786 kilometers and positioned at 58.75°E, 80°E, 110.5°E, 140°E and 160°E respectively. The MEO satellites are operating in orbit at an altitude of 21,528 kilometers and an inclination of 55° to the equatorial plane. The IGSO satellites are operating in orbit at an altitude of 35,786 kilometers and an inclination of 55° to the equatorial plane.”

The China Satellite Navigation Office presented a new official logo for the BeiDou system, with a yin/yang symbol representing Chinese culture, dark and light blue for space and Earth, and the Big Dipper constellation, symbolizing a long tradition of Chinese navigation since ancient times.

A spokesperson said the English name for China’s GNSS will be BeiDou Navigation Satellite System, abbreviated as BDS. The name Compass, which first designated the prototype regional system and has been employed in conjunction with the name BeiDou, will apparently now be discontinued.

Other salient details from the ICD include:

Signal Structure. “The B1 signal is the sum of channel I and Q which are in phase quadrature of each other. The ranging code and NAV message are modulated on carrier. The signal is composed of the carrier frequency, ranging code and NAV message.

“The B1 signal is expressed as follows:

S ^j (t) = A _I C _I ^j (t) D _I ^j (t) cos (2 π f₀ t φ ^j) + A _Q C _Q  ^j (t) D _Q ^j (t) sin (2 π f₀ t + φ ^j)

where superscript j is the satellite number; subscript I equals channel I; subscript Q is channel Q; A is the signal amplitude; C the ranging code; D the data modulated on ranging code; f₀ represents the carrier frequency; and φ the carrier initial phase.”

The nominal frequency of the B1I signal is 1561.098 MHz.

As is the norm with most other GNSSs, BeiDou’s transmitted signal is modulated by quadrature phase shift keying (QPSK). The transmitted signal will be right-handed circularly polarized (RHCP), and its multiplexing mode is code-division multiple-access (CDMA).

User-Received Signal Power Level. “The minimum user-received signal power level is specified to be -163 dBW for B1I, which is measured at the output of a 0 dB RHCP receiving antenna (located near ground), when the satellite’s elevation angle is higher than 5 degree.”

Bandwidth and Suppression. “Bandwidth (1 dB): 4.092 MHz (centered at carrier frequency of B1I); Bandwidth (3 dB): 16 MHz (centered at carrier frequency of B1I). Out-band suppression: no less than 15 dB on f₀±30 MHz, where f₀ is the carrier frequency of B1I signal.”

Ranging Code on B1I. “The chip rate of the B1I ranging code is 2.046 Mcps, and the length is 2,046 chips. The B1I ranging code (hereinafter referred to as CB1I) is a balanced Gold code truncated with the last one chip. The Gold code is generated by means of Modulo-2 addition of G1 and G2 sequences which are respectively derived from two 11-bit linear shift registers.”

NAV Message. “NAV messages are formatted in D1 and D2 based on their rate and structure. The rate of D1 NAV message which is modulated with 1 kbps secondary code is 50 bps. D1 NAV message contains basic NAV information (fundamental NAV information of the broadcasting satellites, almanac information for all satellites as well as the time offsets from other systems); while D2 NAV message contains basic NAV and augmentation service information (the BDS integrity, differential and ionospheric grid information) and its rate is 500 bps.

“The NAV message broadcast by MEO/IGSO and GEO satellites is D1 and D2 respectively.”  The adjacent table from the BeiDou ICD gives information on nav message contents.

First Demonstration of Galileo-Only Positioning

By Peter Steigenberger, Urs Hugentobler, and Oliver Montenbruck

The European satellite navigation system, Galileo, is currently in its in-orbit validation (IOV) phase with a constellation of four satellites. The satellites, launched in pairs on October 21, 2011, and October 12, 2012, are representative of the full 30-satellite constellation. The IOV satellites will demonstrate that the satellites and the ground segment meet the system’s requirements and will validate the system’s design before completion of the rest of the constellation.

The IOV satellites have already started transmitting signals, and short periods of four-satellite visibility have allowed us to demonstrate, for the first time, absolute and relative positioning using measurements from Galileo operational satellites only. This follows the positioning demonstration last year with the signals from the Galileo IOV Element (GIOVE) test satellites and the first two IOV satellites. As in that earlier work, external orbit and clock information is necessary, since the IOV satellites were not transmitting valid navigation messages at the time of our study.

Three Javad GNSS Triumph-VS receivers with external antennas were set up at Technische Universität München (TUM) in Munich, Germany. The reference station TUME is equipped with a Javad GNSS RingAntG3T choke-ring antenna whereas the stations TUMW and TUMO are equipped with Javad GNSS GrAntG3T antennas. Unfortunately, all antennas are mounted near metal surfaces introducing pronounced multipath effects. The resulting baseline lengths are approximately 19.4 meters for TUME-TUMW and 101.7 meters for TUME-TUMO. Galileo satellite orbit and clock information was determined from stations of the Cooperative Network for GNSS Observation (CONGO) and the Multi-GNSS Experiment (MGEX) of the International GNSS Service (IGS). For GPS satellites, the rapid products of the Center for Orbit Determination in Europe (CODE) were used. All computations were performed with a modified version of the Bernese GPS Software 5.0.

Figure 1. Single-point positioning results for the TUME reference station based on E1/E5a dual-frequency pseudorange measurements of the four Galileo IOV satellites. The standard deviations in the north, east, and up directions are given. Note the different scale of the north component.

At a cutoff angle of 10 degrees, the four IOV satellites were jointly visible from TUM on January 6, 2013, for about two hours – from 04:16 to 06:09 UTC. Using an ionosphere-free dual-frequency linear combination of pseudorange measurements on the Galileo E1 and E5a frequencies, the position of the TUME reference station could be determined with a 3D position error of less than 1.5 meters (see Figure 1).

In addition to absolute positioning, relative positions between pairs of receivers were computed from Galileo E1, E5a, E5b, and E5 AltBOC single-frequency carrier-phase observations. Two GPS solutions covering the same time interval serve for comparison purposes. The first solution utilizes all visible GPS satellites (9 to 12 per epoch) whereas the second solution is intentionally limited to four satellites (G06, G16, G27, G29) for best comparison with the Galileo case. So-called kinematic-style processing was used where the baseline is not constrained to be unchanging and a relative-position solution is computed for each epoch of measurements. 3D standard deviations of the different solutions are listed in Table 1. The overall accuracies are at the level of a few centimeters.

Tabe 1. 3D position errors (standard deviation) of carrier-phase-based kinematic-style Galileo and GPS baseline solutions.

A slightly degraded performance is achieved for the TUMO-TUME baseline, which can be attributed to both the larger separation and the inferior multipath environment compared to the TUMW-TUME baseline.

Comparing the individual Galileo signals, the best relative positioning results were obtained for the E1 carrier-phase measurements. Interestingly, the use of carrier-phase measurements from the E5 AltBOC tracking yielded a lower performance in our test than use of either the E5a or E5b observations.  Apparently, the carrier-phase tracking benefits less from the ultra-wideband signal than the code tracking, where AltBOC usually offers notably reduced noise and multipath.  Besides their good performance for Galileo-only positioning, the E1 and E5a carrier-phase measurements will be particularly relevant for future relative positioning applications due to the possibility of mixed-constellation ambiguity resolution with GPS L1 and L5 signals.

For illustration, Figure 2 shows the Galileo E1 solution as well as the GPS L1 solution computed from four satellites. For the north component, the scatter of the Galileo solution is larger by a factor of two compared to GPS whereas it is on almost the same level for the east and up components as a result of the specific geometry of the satellites employed.

Figure 2. Kinematic positioning results for the TUMW-TUME baseline based on Galileo E1 (left) and GPS L1 (right) carrier-phase observations of four satellites. The standard deviations in the north, east, and up directions are given. Note the different scale of the north component.

With the recent testing of navigation messages on the first pair of IOV satellites, Galileo-based positioning as described in this article will not be limited to post-processing, but will be available to real-time users as well.

Peter Steigenberger is a staff member in the Institut für Astronomische und Physikalische Geodäsie of the Technische Universität München (TUM) in Munich, Germany.

Urs Hugentobler is the head of the Fachgebiet Satellitengeodäsie (Department of Satellite Geodesy) and the Forschungseinrichtung Satellitengeodäsie (Research Facility for Satellite Geodesy) at TUM.

Oliver Montenbruck is the head of the GNSS Technology and Navigation Group in the German Space Operations Center in Oberpfaffenhofen, Germany, and a TUM associate faculty member.

Galileo IOV-3 Broadcasts E1, E5, E6 Signals

By Oliver Montenbruck, German Space Operations Center and Richard B. Langley, University of New Brunswick

After reaching its final position, the Galileo IOV-3 satellite started transmitting its first ranging signals on December 1. Within three days, the various carriers (E1, E5, E6) and associated modulations were activated, and full in-orbit testing is now in progress. Anyone with commonly available GNSS receivers can presently access the open signals in the E1, E5a, and E5b frequency bands as well as the wide-band E5 AltBOC signal.

According to statements made at the recent 6th ESA Workshop on Satellite Navigation Technologies (Navitec 2012) in Noordwijk, The Netherlands, the IOV-3 satellite, which is also identified as Flight Model 3 (FM3) and E19 after its pseudorandom noise code, will continue to use binary offset carrier modulation — specifically BOC(1,1) — on the E1 Open Service signals for the time being. In contrast to this, the first pair of IOV satellites has already started to use composite binary offset carrier modulation, which offers better multipath suppression in the received signal.

Right after its activation, IOV-3 could be tracked immediately by the global network of stations participating in the Multi-GNSS Experiment (MGEX; http://www.igs.org/mgex) initiated by the International GNSS Service (IGS).

Figure 1. Pseudorange errors of IOV-3 tracking at Tanegashima, Japan, using the E1 BOC(1,1) signal (top) and the E5 AltBOC signal (center). The elevation angle over time is shown in the bottom panel.

The high quality of the IOV-3 signals is illustrated by measurements collected by the Tanegashima station during a 10-hour pass of the satellite over Japan (see Figure 1). The E5 AltBOC pseudorange measurements in particular exhibit an exceptionally low noise and multipath level of better than 10 centimeters at mid- and high-elevation angles.

An attractive feature of the Galileo system is the availability of multiple signal frequencies, which opens up numerous prospects for precise positioning and scientific investigations.

Carrier-Phase Measurements

While the E6 signals foreseen for a future Commercial Service are not presently supported by geodetic receivers due to the lack of information on the transmitted codes and possible licensing issues, users can already benefit from the E5a and E5b signals in addition to E1. By way of example, the ionosphere-free and geometry-free linear combination can be formed from carrier-phase measurements on these frequencies. Results of some first tests using this combination for IOV-3 are shown in Figure 2, based on measurements made at four MGEX stations: CUT0 (Perth, Australia), GMSD (Tanegashima, Japan), KZN2 (Kazan, Russia), and SIN1 (Singapore).

The results provide an indication of carrier-phase noise and multipath effects but are free of long-term variations that have earlier been found in GPS L1/L2/L5 signal combinations.

It is anticipated that similar measurement quality will be obtained with the E1 and E5 signals of IOV-4, which were activated on December 12 and 13.
This level of performance highlights the potential benefit of Galileo signals in advanced triple-frequency techniques such as undifferenced ambiguity resolution and ionospheric monitoring.

Figure 2 The difference between the ionosphere-free carrier-phase combinations formed from E1/E5a and E1/E5b signals received at four MGEX stations: CUT0 (Perth, Australia), GMSD (Tanegashima, Japan), KZN2 (Kazan, Russia), and SIN1 (Singapore).

Russian SBAS Luch-5B in Orbital Slot

The second Russian satellite-based augmentation system (SBAS) satellite, Luch-5B, has now been positioned at its designated orbital slot of 16 degrees west longitude. The satellite had been in a drift orbit since its launch on November 2 at 21:04:00 UTC along with the domestic communications satellite Yamal-300K.

NORAD/JSpOC tracking data showed Luch-5B arriving at its geostationary position by about December 13. Figure 3 shows the footprint of the satellite with the elevation-angle contours at 30-degree intervals.
Luch-5B, the second of a set of three geostationary satellites being  launched to reactivate Roscosmos’s Luch Multifunctional Space Relay System, is expected to use PRN code 125.

The Luch system will relay communications and telemetry between low-Earth-orbiting spacecraft, such as the the Russian segment of International Space Station, and Russian ground facilities. The system’s satellites also carry transponders for the System for Differential Correction and Monitoring (SDCM), Russia’s SBAS. The transponders will broadcast GNSS corrections on the standard GPS L1 frequency.

Luch-5A, launched in December 2011, resides in an orbital slot at 95 degrees east longitude. It began transmitting corrections on July 12, 2012 using PRN code 140.

Figure 3. Geostationary position of Luch-5B, carrying a transponder for the Russian System for Differential Correction and Monitoring.

EGNOS and Galileo in Emergency Call, Road Tolling

The Intelligent Transport Systems (ITS) World Congress in Vienna this fall drew attention to the multi-constellation advantages provided by Galileo during a session on eCall, the European initiative for safer mobility. “Galileo will provide accuracy and reliability in all the transport markets, but in the case of emergency rapid assistance, the positioning need is even more critical,” said Fiammetta Diani, market development officer at the European GNSS Agency (GSA).

A multiconstellation approach for eCall and similar initiatives will deliver better performance without additional costs. Yaroslav Domaratsky from NIS-GLONASS, the Russian national navigation services provider, confirmed that ERA-GLONASS, the Russian version of eCall, will benefit from multiconstellation. “Solutions including also Galileo are welcome in the Russian initiative.”

Satellite ITS applications in road transport cover much more than in-car navigation. They include road-user charging with satellite-based toll collection systems; in-vehicle dynamic route guidance for drivers; intelligent speed adaptation to control the speed of vehicles externally; traveller information systems; and fleet-tracking systems for better management of freight movements and goods delivery.

Road Tolling

European road-toll operators outlined how they plan to emply the European Geostationary Navigation Overlay Service (EGNOS) and Galileo to provide new tolling solutions.

Luigi Giacalone, managing director of Autostrade Tech, which provides the technology for the French Ecomouv project, said EGNOS will contribute to reliably collect taxes on the heavy trucks using the road charging scheme. “This is a tax, not a toll. It aims to collect a new tax reliably and fairly according to distance travelled, while dissuading fraud,” he said. “Thanks to GNSS multi-constellation, only 10 locations out of the 15,000-kilometer network need support beacons.”

Ecomouv, which Includes anti-jamming and anti-spoofing mechanisms, covers 600,000 French lorries and 200,000 foreign ones, and will run from July 2013 for 11.5 years. Giacalone said its performance target was 99.75 percent accuracy of the entire collection chain, and its trials had already 99.8 percent accuracy.

Miroslav Bobošík from SkyToll, which operates Slovakia’s electronic tolling operations, explained how the system was able to cover not only 570 kilometers of motorways, but also 1,800 kilometers of first class roads in the country. “We needed a flexible system to cover different roads in different circumstances. And also to be fair to drivers, so they pay only for what they use,” said Bobošík. “We cover all services, not just toll collection, but enforcement, and technological maintenance and repair.”

GNSS tolling means flexibility as well as feasibility for SkyToll: since  its launch in mid-2010, many changes have been made to the operation of the network, but thanks to the technology, they were easy to make. And they were cheap, he said. “While it is difficult to compare costs with other country, SkyToll has the lowest cost per kilometer to operate,” he said. “GNSS is the best possible solution for electronic tolling system in Slovakia, and GNSS is the most suitable for ITS.”

Changing the Game

Volker Vierroth from T-Systems, the German IT services subsidiary of Deutsche Telekom, explained GNSS’s game-changing role: the availability of a huge variety of additional data linked to actual positions; more computing power, notably mobile and cloud-based; fast and reliable networks available now with broad coverage, most recently with the shift from 3G to 4G; and smartphones, powerful and versatile, surging to the fore.

“GNSS [in the form of EGNOS] has proved to be a reliable technology for large-scale road charging on complex networks,” he said. “Galileo will bring further improvements, and may become the cornerstone of future road applications.”

Compass ICD Rumored

As this magazine goes to press, unconfirmed reports from Shanghai state that the Compass Interface Control Document (ICD) will be released on December 27.

Such rumors surfaced in late 2010 and again in late 2011. An October 2011 GPS World newsletter reported “The long-awaited signal ICD for China’s growing GNSS will appear this month, according to representatives of the system who spoke in a “Compass: Progress, Status, and Future Outlook” workshop in September [2011].

“The ICD has been rumored to be available previously to receiver manufacturers within China, creating some disgruntlement among companies outside the country. A workshop panelist affirmed that GPS/Compass chips and receivers are being actively developed by many Chinese manufacturers and research institutes.”

Vague rumblings emerged throughout spring and summer this year that two British technologists, backed by the U.K. Ministry Defense, had filed patents on the future interoperable GPS and Galileo binary-offset carrier signal designs. If granted and enforced, the patents would have severely disrupted modernization plans for both systems and levied unexpected costs upon receiver manufacturers. A company called Ploughshare Innovations Ltd. started contacting manufacturers and asking for payment of royalties, based on the patent filings.

After significant uproar and negotiations before and behind the scenes, it now appears that the initiative has been quietly scuttled. The U.S. Patent Office file on application number 11/774,412, Modulation Signals for a Satellite Navigation System, on the Patent Office’s website, now reads “Expressly Abandoned — During Examination.” The status is dated September 16, 2012, some time ago, but none of the parties involved, whether as filers or negotiators, has made any public announcement about it.

Both Sides Now. Checking the European Patent Office and its registry — which is no trivial task of website navigation — turns up a note, dated September 24, under the docket for EP1830199, Modulations Signals for a Satellite Navigation System. The note states “Patent surrendered.”  A few days later, another note: “Lapsed in a contracting state announced via postgrant inform. From Nat. Office to EPO,” with further information to the effect of “lapse because of failure to submit a translation or the description or to pay the fee within the prescribed time limit.”

For good measure, a final docket note on October 3: “Lapsed due to resignation by the proprietor.”

Lockheed Martin Logs Enviro OK on GPS III Sat

The Lockheed Martin team developing the U.S. Air Force’s GPS III  satellites has completed thermal vacuum testing for the Navigation Payload Element (NPE) of the GPS III Non-Flight Satellite Testbed (GNST). The milestone is one of several environmental tests verifying the navigation payload’s quality of workmanship and increased performance compared to the current generation of satellites.

During thermal vacuum testing, the navigation payload’s performance was proven in a vacuum environment at the extreme hot and cold temperatures it will experience on orbit to ensure it will operate as planned once in space. Following the test, the NPE will now be integrated with the GNST for final satellite level testing.

The GNST is a full-sized prototype of a GPS III satellite used to identify and solve development issues prior to integration and test of the first space vehicle. The approach significantly reduces risk, improves production predictability, increases mission assurance and lowers overall program costs. Following integration and test at Lockheed Martin’s GPS Processing Facility (GPF) near Denver, the GNST will be shipped to Cape Canaveral Air Force Station, Florida, for risk reduction activities at the launch site.

Lockheed Martin is on contract to deliver the first four GPS III satellites for launch. The Air Force plans to purchase up to 32 GPS III satellites.

Galileo IOV Satellites in Position

The Galileo In-Orbit Validation (IOV) satellites launched on October 12 (Flight Model 3 and 4), have now been positioned in their designated orbits, according to tracking data from the U.S. Joint Space Operations Center. A plot of the IOV constellation is now available at http://gge.unb.ca/test/Galileo.argper.690.432000.pdf.

The four IOV satellites are in two orbital planes separated by about 120 degrees. Within each plane, the satellites are separated by about 40 degrees. This orbital arrangement will allow the four satellites to be simultaneously tracked for periods of time by GNSS monitoring stations, permitting positioning tests using only IOV data to be carried out. However, no signals from FM3 or FM4 have yet been detected by stations of the International GNSS Service.

GPS III SATELLITE, artist’s rendering, courtesy Lockheed Martin.

Raytheon Company and Lockheed Martin successfully completed the first launch readiness exercise for the U.S. Air Force’s next-generation GPS III satellites. The exercise is a key milestone demonstrating the team remains on schedule to achieve launch availability in 2014, the companies said.

The Lockheed Martin-built GPS III satellites and the Raytheon-developed next generation GPS operational control system, known as OCX, are critical elements of the U.S. Air Force’s effort to affordably replace aging GPS satellites while improving capability to meet the evolving demands of military, commercial and civilian users worldwide. This is the first space and ground enterprise successfully building the ground control and space vehicles by two independent prime contractors.

The launch readiness exercise, completed over a three-day period by mission operations personnel, validated the basic satellite command and control functions, tested the software and hardware interfaces and demonstrated basic on-console procedures required for space vehicle contacts during the launch and early orbit mission.  The event sets the stage for the first GPS III satellite’s mission readiness timeline, which includes five short-duration exercises and six, five-day mission rehearsals leading up tolaunch.

To achieve first launch availability in the 2014 timeframe, the U.S. Air Force awarded Lockheed Martin and Raytheon contracts in January of this year to provide a Launch and Checkout Capability (LCC) for launch and early on-orbit testing of all GPS III satellites.  At the heart of the LCC is Raytheon’s Launch and Checkout System that will provide satellite command and control capability, an integral part of OCX’s  support of the first GPS III launch.

Rockets on the Pad

As this magazine goes to press on September 17, several GNSS satellite launches are pending, and may have already occurred by the time you read this. Launch dates this fall for GNSS satellites in the coming season are as follows, according to various, not always official, sources. Compilation courtesy of CANSPACE.

Compass M2 and M5. September 18, 18:12 UTC (speculative).

GSAT-10. Carrying a satellite-based augmentation system (SBAS) transponder for  the  GPS-aided geo-augmented navigation system (GAGAN), a planned implementation of a regional SBAS by the Indian government: September 21.

Compass G6. No earlier than October 1.

GPS IIF-3. October 4. Launch window: 12:10-12:29 UTC.

Galileo IOV FM3 and FM4. October 10, 18:31 UTC.

Luch-5B. For the Russian SBAS. Originally scheduled for October 15, launch has slipped to no earlier than November 1 due to an issue with the Briz-M upper stage, which caused the loss of the Telkom-3 and Ekspress-MD2 communication satellites during their launch on August 6.

GLONASS-K1 (block K2s). November 14.

The fourth Galileo flight model satellite is unloaded at Cayenne Airport in French Guiana August 17. (ESA/EADS Astrium, Raoul Kieffer)

JAVAD: Filters Protect GPS L1, L2, L5; GLONASS L1, L2; Galileo L1, L5

Javad Ashjaee, founder and CEO of JAVAD GNSS, filed a September 7 letter with the U.S. Federal Communications Commission (FCC) concerning his company’s development of technical possibilities in GNSS filter designs and components. He stated “I hope this will be helpful in establishing realistic guidelines for the characteristics of high-precision GNSS receivers that will be used in critical applications.”

The letter reads, in part:

“We have improved our previous L1 filter and have extended the design to include all commercial GNSS bands.”

“Our filter . . . protects GPS L1, Galileo L1 and GLONASS L1 bands. It brings in all the useful signals intact and rejects out of band signals with the slope of about 12 dB/Mhz. Similarly . . . our filter . . . . protects GPS L2, GPS L5, GLONASS L2 and Galileo L5 and has slope of about 9 dB/Mhz.

“These filters not only protect GNSS signals against all LightSquared signals (10L, 10H and 10R handsets) but also from all similar signals that may appear near all commercial GNSS bands in the future. We are proud that our filters help allow better usage of these precious bands, in particular for broadband wireless communication that our country desperately needs.

“These filters apply to wideband high precision GNSS receivers and the cost is even less than earlier conventional filters. The case of narrow-band low precision receivers (e.g. Garmin) is much simpler, as has been demonstrated by GPS receivers in more than 300 million cell phones and mobile devices which are not affected by LightSquared signals. The low precision receivers (L1 C/A code only) require filter slopes 10 times less steep than those presented here and do not necessitate additional costs.”

Galileo Headquarters Moves to Prague

The Galileo headquarters in Prague.

On September 6, the European GNSS Agency (GSA) inaugurated its new premises in Prague, Czech Republic. Previously headquartered in Brussels, the headquarters of the Galileo program moved its seat to Prague this summer, as agreed by the EU heads of state and government in December 2010.
Galileo is expected to be partly operational by the end of 2014. Two in-orbit validation (IOV) satellites will be launched in October, bringing the total in space to four, sufficient for initial check-outs.  Beginning in 2013, four more Galileo satellites will be launched every six months until the network of 30 is completed in 2020.

GSA ensures security of satellites and prepares ground for new GNSS products. The agency is responsible for a number of implementation tasks for the European Satellite Navigation programmes Galileo and  the European Geostationary Navigation Overlay Service (EGNOS), which are managed by the European Commission. Its two main tasks are:

• Security accreditation of satellites, launchers, and sites, and the operation of the Galileo Security Monitoring Centre, and
• Market development for the European satellite navigation systems, such as new products and services possible using Internet access to satellite navigation data, among others.

Future Role. A European Commission (EC) proposal for revising the GNSS Regulation foresees that operational responsibility for the GNSS programmes will be gradually transferred from the EC to the GSA over the next multi-annual financial framework (2014-2020). This represents a reversal of an earlier move, or a restoration of a previous state; after delays and budget disputes with manufacturers during the tentative public-private partnership (PPP) phase, the European Commission took direct control of the Galileo program, effectively sidelining the GSA.

The transfer of responsibility will start with EGNOS in 2014, and already a number of preparatory tasks have been allocated to the GSA, including the procurement for the future operations of EGNOS.

To carry out these new functions, the GSA’s staff is expected to increase from about 60 today to more than 180 by the end of next financial framework in 2020.

Budget. The GSA has an annual budget of about €12.75 million ($16.75 million) in 2012, plus €34.4 million ($45 million) for exploitation activities.
According to European Commission calculations, a total budget of € 7 billion ($9.2 billion) is necessary to complete the deployment phase of the Galileo programmes and finance the exploitation phase of the GNSS programmes over the 2014-2020 period.

Compass Energizes China’s Economy

China’s Beidou/Compass system will spur the country’s economic development in the satellite-navigation industry, geoinformation, and location-based services, according to an article in China Daily. China’s civil navigation providers are likely to experience rapid growth during the 12th Five-Year Plan (2011-15) period.

The deputy director-general of the National Administration of Surveying, Mapping and Geoinformation said the government is likely to introduce policies to help the geoinformation industry grow.

“In addition, the nation’s self-developed satellite navigation network, the Beidou Navigation System, will come into commercial use by the end of this year, a move that may stimulate the development of the geoinformation industry in China.”

Aviation NextGen May Show Slow ROI

An inspector from the U.S. Department of Transportation testified in Congress that benefits from the GPS-based air traffic control system Next Gen may take longer to realize than had been expected. Although the Federal Aviation Administration (FAA) has improved its management of the modernization program, years of delays and cost over-runs have left airlines dragging their feet in turn over multibillion-dollar equipment upgrades needed for the new system to work.

The inspector stated the investment will be worth the taxpayer cost in the long run, and will produce significant safety and scheduling benefits. U.S. air travel is expected to nearly double over the next two decades, bringing an unbearable burden onto the current air traffic control system, if not significantly upgraded.

By 2020, the new system is expected to reduce delays by 38 percent compared with the current system; airlines, passengers, and taxpayers are estimated tosave $24 billion.

The FAA plans to spend $2.4 billion over the next five years on a collection of six programs evolving from an outdated, radar-based system to one that uses GPS and telecommunications advances for precision tracking, making routes more direct, eliminating many weather delays, and enabling planes to fly safely at closer distances. Once fully in place, the modernization program will save 1.4 billion gallons of fuel and reduce carbon dioxide emissions by 14 million metric tons, the FAA says.

However, planes must be equipped with new equipment at a cost of hundreds of thousands of dollars per aircraft. NextGen doesn’t start yielding full benefits until a critical mass of planes have the new technology.


Unmanned aerial vehicles and civil aircraft may co-habit the airspace after September 2015.

 As the U.S. Federal Aviation Administration (FAA) moves ahead with plans for unmanned aerial systems/vehicles (UAS/UAV) to have regular access to U.S. airspace by 2015, it has encountered several barriers. For UAVs to be treated like manned aircraft, their systems likley need to be qualified to the same standards as civil avioncs. This is a challenge, as each UAS has largely unique systems. UAS equipment standards are emerging, but threats to GNSS abound, requiring defense/mitigation.

Demand for UAS has produced many different types flying in a range of applications. With no apparent standard avionics fit or uniform safety standards, each UAS type is basically configured for specific tasks. Commercial UAS applications continue to emerge, and major market growth is anticipated. One forecast indicates that the UAS market could reach $7.26 billion this year alone. The promise of new and better ways to reduce costs, improve safety, and increase operational efficiency feeds market expansion.

However, in the United States the FAA currently requires each UAS commercial project desiring access to controlled airspace to obtain an FAA-approved Certificate of Authorization. While the FAA has made efforts to speed up approvals, this process slowed widespread commercial adoption of UAS. Nevertheless, opportunities abound in pipeline and transmission line inspection, crop spraying, law enforcement, security, and surveillance, survey/mapping, remote area mail delivery, and hundreds of other applications. The FAA may have felt some pressure to move forward, because Congress has put in place the Modernization and Reform Act of 2012, which calls on the FAA to fully integrate unmanned systems, including those for commercial use, into the national airspace by September 2015.

UAS in the NAS. Meanwhile, a project called the Unmanned Aircraft Systems Integration in the National Airspace System (UAS in the NAS), undertaken by NASA’s Dryden Flight Research Center, seeks to reduce technical barriers related to safety and operational challenges associated with enabling routine UAS access to the NAS.

Europe has also launched a study on the integration of UAS in non-segregated airspace for the future Single European Sky. The ICONUS study will be carried out by a consortium within the European air traffic management program called Single European Sky ATM Research Programme (SESAR). The study will drive the definition of the requirements, capabilities, and equipment which UAS will need to operate safely and efficiently in the coming European SESAR environment.

The U.S. RTCA SC-203 committee is drafting UAS operational requirements, and there has been significant progress towards publishing Minimum Aviation Performance Standards (MASPS), including requirements for navigation. Europe has similar activities underway aimed at improving UAS access to its airspace.

MOPS. The big picture is that requirements for unmanned aircraft are being brought into conformance with the standards applied to the performance and behavior of manned aircraft. Navigation requirements for UAS are expected to specify that systems will need to be qualified to Minimum Operational Performance Standards (MOPS). This means that on-board electronics, including GNSS systems, will probably need to be FAA Technical Standard Orders (TSO) qualified, just as they are now for manned aircraft.

Why do we need to investigate certified avionics now? In the scheme of avionics, more than two years breathing space to certify UAS avionics systems is not a long time, not at all, until the September 2015 deadline. FAA airborne software and hardware qualification will take much time and effort to implement, and re-configuration of systems, interfaces, and operating procedures may take even longer.

For Manufacturers. UAS makers have the option to move forward in stages. For instance, by selecting a few existing airborne-qualified OEM avionics, they could minimize the internal effort to comply. As the first UAS with certified avionics emerge, they will probably get good support from FAA to adopt U.S. operating rules for the NAS. Embedding an existing certified GPS receiver in UAS avionics will reduce the internal work needed and allow more effort for developing commercial market opportunities that look to quickly adopt UAS.

Meanwhile, efforts are in full swing to change the U.S. and European navigation landscapes over the next few years. So it would be better to be ready with a capable GNSS receiver that is already built to meet the challenges of NextGen and SESAR.

GPS III and Galileo. The L5 civil GPS frequency may be operational around the time that UAS unrestricted access becomes possible. GPS L1/L5 dual-frequency operations will enable higher navigation accuracy, reliablity, and integrity. The FAA is already developing NextGen WAAS to include L5, and revisions to the GPS MOPS to include L5 should begin shortly, in time for a usable GPS L5 constellation in 2015/2016. The FAA is already preparing for L5 avionics, and industry investigative work is underway. Its possible that GPS L1/L5 may meet the accuracy and integrity requirements for CAT II/III automated landings. In Europe, Eurocae work is expected to gain momentum for the Galileo E1/E5a MOPS as the Galileo satellite navigation system becomes operational.

The new GNSS environment also includes WAAS/SBAS precision approach (localizer performance with vertical guidance, or LPV) capability: LPV is available now in the United States and will soon be in wider operation in Europe. Automatic Dependendant Surveillance (ADS-B) is rolling out in the United States and around the world. ADS-B is being mandated within the U.S. NAS as the means for air-traffic control to track all aircraft, so UAS avionics will need to include certified ADS-B Out capability.

In one commercial instance, the Septentrio AiRx2 receiver comes out of the box as a certified L1 GPS with ADS-B and WAAS LVP, but is also ready for GPS L5 and Galileo E1/E5a.

Even as greater steps forward enhance how GNSS is used in this wider definition of aviation that will soon include UAS, a team at the University of Texas demonstrated how a UAV could be maliciously side-tracked (see article on page 30 of this issue) —  reminiscent of the Iranian downing of a U.S. surveillance drone in December 2011.

Admittedly the GPS on the vehicle in the UT test was not a qualified airborne receiver, but how could this happen when there was also an inertial sensor and a radio-altimeter on the UAV? A good question, which UAV manufacturers will need to consider when they implement their on-board Kalman filters, knowing that spoofing is now an additional threat to parry.

Couldn’t we detect that high-power RF spoofing signal at the front-end of the GPS receiver? Even if only to tell the on-board systems that there could be hazardous misleading information about? Or run separate GPS and GPS/inertial position solutions, detect significant divergence, and set the same warning flag? And multi-constellation, multi-frequency receivers, and even controlled radiation pattern antennas — all things to investigate.  More work for the aviation receiver guys who labor tirelessly to improve GNSS integrity.

Of course if you hijack a UAV with a high-power spoofer, you are also spoofing civil transports operating in the same airspace, so now there is the potential to trigger a Federal investigation. It will probably be easier to detect this stuff with moving airborne sensors rather than the fixed ground equipment used to find jammers on trucks at Newark airport, and lots of pilots likely providing real-time location information on radios if their GPS goes even a little haywire. All would help to quickly locate and shut down any spoofer. Nevertheless, it’s a threat to be mitigated.

Fatal Crash. In South Korea, the effects of intermittent North Korean jamming of GPS to disrupt seal, land, and air navigation in the South may have contributed to the recent fatal crash of a Schiebel Camcopter S-100 drone, a 150-kilogram rotorcraft capable of 220 km/h flight. It should have coped with loss of GPS as the Camcopter has multiple inertial measurement units that allow safe operation and recovery in the absence of GPS signals. Emergency procedures to ensure a safe recovery in such a situation do not appear to have been correctly and adequately followed, manufacturer Schiebel alleges.

NovAtel may have found one way to help mitigate spoofing on UAVs; the company released a combined civil/SAASM GPS receiver, the OEM625S, aimed specifically at UAVs. Granted, the idea is to add SAASM anti-spoofing capability to a number of UAVs which currently use NovAtel commercial receivers, mostly in military systems. That may be motivated by the desire to avoid further Iranian incidents!

BAE Systems has been thinking of giving GPS a back-up for just those situations where jamming or even spoofing is detected. BAE’s Navigation via Signals of Opportunity (NAVSOP) system was just announced at the Farnborough air show in the UK and is still in research phase, but looks extremely promising. It interrogates the radio environment for the ID and signal strength of local digital TV and radio signals, plus air traffic control radars, with finer grained adjustments coming from cellphone masts and Wi-Fi routers. Mapping the location of all these sources might be quite an undertaking, and given that these are all non-safety-of-life commercial signals, the sources are subject to the vagaries of power outages, regular maintenance, and breakdowns. Nevertheless, with such a multitude of signals, NAVSOP could well turn out to be a viable back-up for GNSS.

So, shared access to civil airspace, wider applications in commercial operations, and changes in equipment qualification, along with potential solutions for GNSS jamming and spoofing: lots to consider for the UAS industry.

Taking It to the House

U.S. House of Representatives Committee on Homeland Security; Subcommittee on Oversight, Investigations, and Management; Hearing, July 19, 2012:  Using Unmanned Aerial Systems Within the Homeland: Security Game Changer?

Testimony by Todd E. Humphreys, Ph.D.; Assistant Professor, Cockrell School of Engineering, The University of Texas at Austin. [Excerpted. Prof. Humphreys is a co-author of the article “Drone Hack” in the August issue of GPS World.]

The vulnerability of civil GPS to spoofing has serious implications for civil unmanned aerial vehicles (UAVs), as was recently illustrated by a dramatic remote hijacking of a UAV at White Sands Missile Range.

Hacking a UAV by GPS spoofing is but one expression of a larger problem: insecure civil GPS technology has over the last two decades been absorbed deeply into critical systems within our national infrastructure. Besides UAVs, civil GPS spoofing also presents a danger to manned aircraft, maritime craft, communications systems, banking and finance institutions, and the national power grid.

Constructing from scratch a sophisticated GPS spoofer like the one developed by the University of Texas is not easy. It is not within the capability of the average person on the street, or even the average Anonymous hacker. But the emerging tools of software-defined radio and the availability of GPS signal simulators are putting spoofers within reach of ordinary malefactors.

There is no quick, easy, and cheap fix for the civil GPS spoofing problem. What is more, not even the most effective GPS spoofing defenses are foolproof. But reasonable, cost-effective spoofing defenses exist which, if implemented, will make successful spoofing much harder.

I recommend that for non-recreational operation in the national airspace civil UAVs exceeding 18 lbs be required to employ navigation systems that are spoof-resistant.

More broadly, I recommend that GPS-based timing or navigation systems having a non-trivial role in systems designated by DHS as national critical infrastructure be required to be spoof-resistant.

Finally, I recommend that the DHS commit to funding development and implementation of a cryptographic authentication signature in one of the existing or forthcoming civil GPS signals.

Complete testimony (PDF) covers:

• The potential vulnerabilities of U.S. national transportation, communications, banking and finance, and energy distribution infrastructure;
• What does it take to build a spoofer? Buy a spoofer?
• Range and required knowledge of target.
• Fixing the problem:

•    Jamming-to-noise sensing defense;
•    Defense based on SSSC or NMA on WAAS signals;
•    Multi-system multi-grequency defense;
•    Single-antenna defense;
•    Defense based on spread-spectrum security codes on L1C;
•    Defense based on navigation message authentication on L1C, L2C, or L5;
•    Correlation prole anomaly defense;
•    Multi-antenna defense;
•    Defense based on cross-correlation with military signals.