The next GPS satellite launch is scheduled for May 15 with the launch window extending from 21:39 to 21:58 UTC. An Atlas 5 rocket will be used to place the satellite, GPS IIF-4, into orbit from Cape Canaveral Air Force Station.

This is the first time in almost 28 years that an Atlas rocket will be used to launch a GPS satellite. All of the prototype or Block I satellites were orbited with Atlas rockets. Since then, Delta rockets have been used exclusively for GPS launches. The IIF satellites are being launched with a mixture of Atlas and Delta rockets.

The IIF-4 satellite, also known as SVN66, will operate as PRN27. SVN66/PRN27 will eventually occupy the C-2 slot, replacing SVN33/PRN03, a Block IIA satellite launched in 1996. Reportedly, SVN66/PRN27 will go through an extended period of testing following launch, and is not expected to be set healthy until August. SVN33 will become a reserve or backup satellite.

Ground Stations: ER = Eastern Range; BOSS = Call sign of New Hampshire Station, New Boston Air Force Station, New Hampshire; LION = call sign of Telemetry & Command Station, Royal Air Force Oakhanger, Hampshire, U.K.; Diego Garcia = Diego Garcia Station (call sign REEF), British Indian Ocean Territory; Guam = Guam Tracking Station (call sign GUAM), Dededo, Guam.
TDRS: Tracking and Data Relay Satellite
MES1: Centaur first main engine start
MECO1: Centaur first main engine cutoff
MES2: Centaur second main engine start
MECO2: Centaur second main engine cutoff
At spacecraft separation, the GPS satellite’s orbit will be circular with a height of 11,047 nautical miles or 20,459 kilometers and an inclination of 55 degrees.

(Courtesy of SpaceFlight Now) This is the 45th Launch Support Squadron crew patch for the GPS 2F-4 mission, which is Boeing’s Space Vehicle (SV) #5. Each SV is a named for a navigation star and its constellation. SV-5 is named Vega, with constellation Lyra. On the patch, they are the large star and constellation in the background of space. The United Launch Alliance Atlas 5 rocket is shown lifting the satellite from the Eastern Launch Site at Cape Canaveral Air Force Station. The Squadron mascot is a gator, and a lyra is a Greek harp. SSgt Thomas Hogan drew a “Toga-Gator” and Lt Ken Stuart did the patch design.

Applanix AP50 GNSS-inertial system.

The Applanix AP50 GNSS-inertial system is a GNSS-inertial sensor plus inertial measurement unit (IMU) in a compact form factor. It features a high-performance precision GNSS receiver and the Applanix IN-Fusion GNSS-inertial integration technology running on a powerful, dedicated inertial engine (IE) board.

Riegl’s VQ-820-G airborne laser scanner.

On board an unmanned aerial vehicle (UAV), the system is capable of penetrating areas that may be too dangerous for piloted aircraft or ground patrols. This can provide additional safety and security for its users.

“We really appreciate the professional and amicable cooperation with Applanix, which allows us to offer user-friendly and powerful, fully integrated solutions for dynamic data acquisition to the marketplace,” said Jürgen Nussbaum, Riegl director of international sales.

In addition, Applanix will be a Gold sponsor at Riegl LIDAR 2013, Riegl’s international user conference taking place in Vienna, Austria, June 25-27.

Unmanned Innovation’s os-Series Autopilots, made commercially available for the first time in November 2012, combine modular hardware with an open architecture, making each autopilot a development platform.

The os-Series Autopilots are offered in multiple form factors with features tailored for various vehicles, payloads, and applications. Each os-Series Autopilot is a complete integrated solution and contains an INS/GPS with air data incorporating the VectorNav VN-100, a datalink radio, payload interfaces, and a Linux computer within one miniature package, starting at 32 grams. The os-Series Autopilots come with professionally written flight control and mission software that Unmanned Innovation provides under a royalty-free license that allows for easy modification, extension, and inclusion in proprietary products.

The partnership between the two companies began during AUVSI’s Unmanned Systems North America 2012 conference in August, where Unmanned Innovation was introduced to VectorNav’s VN-100 and recognized it as an attractive alternative to its existing inertial measurement sensors due to its small form factor, low-cost, and high-precision calibration. Unmanned Innovation’s flexible architecture allowed for quick integration of the VN-100 and VectorNav provided custom firmware with a faster update rate to make the IMU compatible with Unmanned Innovation’s requirements.

The VN-100 IMU, calibrated for bias, scale factor and misalignment errors at room temperature or over the entire thermal operating range of the sensor increased the accuracy of the os-Series Autopilot navigation solution. After a short development cycle, testing and verification, VectorNav’s VN-100 IMUs are now fully integrated within Unmanned Innovation’s os-Series Autopilots. The complete os-Series product line is shipping to customers in the USA and abroad and is free of ITAR restrictions.

“We are very pleased to be working with Unmanned Innovation on their os-Series Autopilot, which we find to be a very unique and high-value product that fills a significant gap in this market,” said John Brashear, VectorNav’s president. ”We hope that the VN-100 adds to this value by allowing Unmanned Innovation to focus on its strengths improving the os-Series while securing a long-term, dependable sensing solution and partnership with our company.”

The Garmin GTN series features intuitive touchscreen controls and a large-screen display that give Learjet pilots unprecedented access to high-resolution mapping, graphical flight planning, and geo-referenced charting, among many other features. The installation also features new GPS roll-steering that allows seamless navigation operations with turn anticipation and waypoint sequencing interfaced to the autopilot.

“This approval offers a significant and economical avionics upgrade for the Lear 30 series airplanes,” said Clark Stewart, president and CEO of Butler. “The STC for the new Garmin GTN series allows us to tap into a sizeable upgrade market for retrofit of flight management systems. The Garmin GTN upgrade provides significant functionality upgrades, including WAAS GPS approaches and roll-steering interface to the autopilot.”

“We have designed the installation to provide cost-effective options to meet the various Learjet operator requirements. We will be offering the GTN Learjet installations through our avionics facility Kings Avionics starting under $100,000,” commented Craig Stewart, Aerospace division president.

Butler National Corporation operates in the Aerospace and Services business segments. The Aerospace segment focuses on the manufacturing of support systems for commercial and military aircraft including the Butler National TSD for the Boeing 737 and 747 Classic aircraft, switching equipment for Boeing McDonnell Douglas Aircraft, weapon control systems for Boeing Helicopter, and performance enhancement structural modifications for Learjet, Cessna, Dassault, and Beechcraft business aircraft.

Today at Intergeo, NovAtel Inc., NovAtel announced the addition of a new commercially exportable single-enclosure SPAN MEMS receiver to its line of SPAN GNSS/INS products. Available in the first quarter of 2013, the low-power, lightweight SPAN MEMS enclosure incorporates a diminutive Micro Electromechanical Systems (MEMS) Inertial Measurement Unit (IMU) and a NovAtel high-precision OEM615 GNSS/INS SPAN receiver to provide continuously available position, velocity and attitude (roll, pitch and yaw) in a small, single-unit form factor, the company announced.

“This product ensures we meet crucial price/performance and size/weight requirements for our customers,” Jason Hamilton, director of Marketing at NovAtel, said. He added, “By integrating this IMU with our powerful OEM6 GNSS/INS SPAN engine, which provides many advanced positioning options such as AdVance RTK, ALIGN heading technology and RAIM, we are able to offer a GNSS/INS solution for a wide range of applications.”

The lightweight SPAN MEMS enclosure provides a rugged housing for demanding applications. Serial and USB communication interfaces plus several I/O options support additional peripherals. An embedded wheel sensor interface is also available to enhance GNSS outage bridging capabilities. Tight coupling of the GNSS and inertial technologies enables continuous, robust positioning in difficult environments where satellite signals are unreliable or unavailable for short periods of time.

This product will be available as an integrated single-enclosure SPAN solution, enclosed standalone IMU for use with external SPAN-enabled receivers, and as an OEM component.

Shipments of the new receiver start Q1 2013 with OEM availability Q4 2012. A limited supply of enclosure evaluation units will be available in Q4 for integrators looking to get a head start on their projects.

The article “Drone Hack” in the August issue of GPS World and Todd Humphreys’ testimony before a House Subcommittee overseeing the Department of Homeland Security cited results of a spoofing experiment Humphreys conducted with University of Texas colleagues, demonstrating that a drone helicopter, navigating principally on the civil GPS signal, could have its vertical channel spoofed, causing it to descend. Reaction, quite strong from some directions, prompted one observer to investigate whether a “sky-is-falling” perception is fully warranted. Partly for that reason, emails started circulating among various individuals, including some directly involved in the design. When first brought into the group I was not expecting to be the one to summarize, but, as events unfolded, I’m called on to act as techno-sleuth.

Let me first state the conclusion: the sky is not falling. That’s not intended to discourage corrective measures — and it is immediately acknowledged that definitive answers remain unresolved (detailed configuration of the Kalman filter, state estimates, weighting of the baro altimeter). But this much is clear: conditions weren’t 100 percent normal. From here I’ll cover the supporting facts, followed by possible corrective measures. Discussion will be technical, without any hint of administrative authority or approval.

Key revelations came to light in discussion with the chief scientist of Adaptive Flight, who designed the drone’s nav system software and operator interface.

“The reason Todd and his team were able to modify the vertical position of the aircraft even though altitude aiding is actually coming from the pressure sensor,” he stated, “is that the GPS vertical velocity was being used. The spoofed GPS position (altitude error) was actually being ignored.”

We might call that a hybrid mode, using one part of GPS and ignoring another. Selectivity isn’t intrinsically unwise — we need options to reject some data without automatically rejecting other information — but, with GPS-derived altitude ignored for any reason, why not reject all vertical-channel influence from GPS? In fact that’s consistent with normal operation; disabling (again a quote) “GPS vertical velocity as an aid … can be done with a command from the control station (and saved as default for the aircraft).”

Well, then, the demo doesn’t reflect 100 percent normal procedure. Relief: our drones aren’t as vulnerable as we thought, and the fear expressed in various publications can be reduced.

For further support of that conclusion, additional major information from that same designer includes a quote that “The baro altimeter is used to provide a vertical position discrete update to the Kalman filter. This is true for both normal and GPS-denied modes. There are no (automatic) divergence tests in this system. There is some outlier detection/rejection on the GPS (which probably was not triggered in the spoofing tests, but I haven’t seen the data). There is nothing on the baro altimeter.” Finally, he says “it is a trivial change from the control station to make the vertical channel ignore GPS in normal mode by turning off the down GPS velocity measurement update; it would still fly fine.”

The combined weight of all that can justifiably reduce the level of concern — but not all the way down to zero. Now that all this happened, the subject of prevention needs to be addressed.

As Todd Humphreys correctly noted, without spoofing but with existing errors, GPS position updating cannot adequately mitigate low-cost IMU drift.

High-end IMUs bring budget issues (and their motion-sensitive errors limit performance anyway). Spectrum and signal quality is seen by many as an important consideration; residual monitoring is another. For the latter to be effective, the existing (loose) coupling needs upgrading (loose coupling wastes information content; the loss is greatest when GPS coverage is marginal). Extent of refinement (tight/ultratight/deep) and usage of carrier phase (while sidestepping its usual traps) open up a subject with much wider scope: cross-checking. I offer just a few fundamentals here.

• Known data-edit capabilities available with existing provisions (for example, baro altimeter cross-checking), rather than something that “can be done” can always automatically disallow any partial influence from GPS instantly upon spoof detection, regardless of its genesis (Kalman filter bias state traceable to past history or any other source).
• The step just noted generalizes to include all sensor data extant onboard, including carrier phase. The specter of huge expense for this particular step is nonessential; some receivers output raw measurements that can be put into public domain algorithms.
• With access to all the raw data, every solution combination — federated and integrated — can be generated for cross-checking. In all cases, thresholds for residual testing are set with conservative assessments of sensor error statistics; this overbounding enables integrity testing to err on the side of caution (sacrificing some valid data to better ensure rejection of bad). Integrity test algorithms are likewise public domain.

I close by paraphrasing an observation offered by Mitch Narins in a LinkedIn discussion: Deter threats before they happen. With a robust non-GNSS PNT alternative, spoofing will have no affect on safety or security.

 — James L. Farrell
President, VIGIL, Inc.
Severna Park, Maryland

Trimble has introduced at the ION GNSS Conference in Nashville the Trimble BD920-W3G receiver and communication module. As part of Trimble’s GNSS OEM portfolio, the new compact module features centimeter-level, real-time kinematic (RTK) positioning capabilities coupled with Wi-Fi, Bluetooth and cellular that deliver flexible communication options for precise, mobile positioning. The BD920-W3G module’s connectivity and configuration ease allow system integrators and OEMs to easily add GNSS centimeter-level positioning to specialized or custom hardware solutions, Trimble said.

“The OEM and system integrator communities demand high performance, reliability and support for their positioning solutions,” said Dale Hermann, director of marketing and sales. “The Trimble BD920-W3G delivers the latest in GNSS and communication technology in an easy-to-integrate form factor for demanding conditions and applications such as field computing, port automation, and lightweight robotic or unmanned vehicles.”

The Trimble BD920-W3G module has been designed for applications requiring centimeter accuracy in a compact package. By integrating wireless communications on the same module, the task of receiving and transmitting data such as RTK corrections is greatly simplified. A single intuitive Web interface allows a variety of use cases to be supported. In addition to GNSS base and rover setups with Wi-Fi or UMTS modem, the module also allows simultaneous customer access to the Internet.

The dual-frequency GPS/GLONASS BD920-W3G provides customers with a more integrated product that can reduce their integration effort and time to market. Wireless communications and Ethernet connectivity are available on the module to allow high-speed data transfer and configuration via standard Web browsers. USB and RS232 are also supported. By tightly integrating communications and GNSS receiver, integrators can reduce costs and integration complexity, the company said.

The Trimble BD920-W3G is expected to be available in the first quarter of 2013 through Trimble’s Precision GNSS + Inertial sales channel worldwide. The BD920-W3G can be viewed in 3D on Trimble’s 3D Warehouse by SketchUp. OEMs and integrators can also download a 3D model into their applications. For more information, visit www.trimble.com/gnss-inertial.

L-3 Interstate Electronics Corporation (IEC) conducted an operational demonstration of its new TruTrak Evolution (TTE) Type II Selective Availability Anti-Spoofing Module (SAASM) GPS receiver at AUVSI’s Unmanned Systems North America 2012 conference, held last week in Las Vegas. The demonstration highlighted the new TruTrak receiver’s multi-use capabilities as a high-performing Ground-Based GPS Receiver Applications Module (GB-GRAM) for use on UAS platforms and precision weapons.

The TTE offers native Inertial Measurement Unit (IMU) and external oscillator interfaces, user processor, reconfigurable input/output (I/O) and front end, and easy roadmap migration from SAASM to NextGen GPS YMCA modernized technology. Its TTE Type II architecture supports the integration of multiple sensors to simplify all-source navigation solutions for GPS-denied environments. The adaptable architecture allows developers to quickly integrate new sensors without a hardware change, while providing industry-leading core GPS receiver performance and easy migration to NextGen modernized GPS.

“The TTE Type II highlights L-3 IEC’s integrated SAASM/NextGen GPS M-Code roadmap, providing another innovative path in the development of a Common GPS Module,” said Ric Pozo, general manager and vice president of navigation systems at L-3 IEC. “It allows SAASM- based P(Y) and modernized YMCA multichip modules to share a common circuit card assembly, making this a very flexible solution for drop-in GPS receiver replacement and low-risk integration.”

L-3′s TTE Type II provides features required by multiple applications, including a small form factor, high performance, and both passive and active antennas. The TTE Type II adopts the common GB-GRAM Type II electrical and physical interfaces, but with expandable I/O to support a wide range of requirements for ground, air, weapon, and projectile needs.