The System: Technical Report on LS/GPS Interference

August 1, 2011  - By
Image: GPS World

Once again, developments in the news outpaced print technology’s ability to keep up in the LightSquared saga. Shortly after the July issue went to press on June 27, the TWG final report appeared on June 30. Thus you readers, who received the magazine circa July 15, held old news in your hands. Likely this will occur again.

Chronologically in this section, from late June to mid-late July:

Final Report of Technical Group

The final report to the Federal Communications Commission (FCC) by the technical working group (TWG) tasked to analyze effects of powerful terrestrial L-band transmitters on the GPS signal and services finally appeared on June 30, nearly two weeks after its assigned date. LightSquared had requested an extension and used the time to write many pages of self-justification and legal argument of the company’s case. But the facts are clear: the LightSquared signal would devastate services for users of all GPS receivers tested.

“Based on the analysis performed, LightSquared should not be permitted to use the L-Band spectrum for a densely-deployed, non-integrated terrestrial-only network. Such a network would cause unacceptable interference to GPS operations, wiping out an installed base of over 500 million units used in a wide array of public safety, aviation, industrial, and consumer applications. While mitigation techniques utilizing filters were discussed in theory, they could not be tested as part of the WG effort because filters do not exist, even in prototypes. No information considered by the WG demonstrated that any mitigation techniques — other than relocation of the proposed terrestrial network to an alternative band — would be successful.” (From the U.S. GPS Industry Council’s overview)

The final report is not easy to find on the FCC’s labyrinthine website. Download it here.

LightSquared COO, President Gone

Harbinger Capital Partners, the hedge-fund firm that owns LightSquared, announced on July 6 that its chief operating officer had resigned by “mutual agreement.” Peter Jenson’s exact role in the application for a FCC conditional waiver is unknown at this time; however, it is certain to have been key.

On June 30, the date of the TWG report, Harbinger Group Inc., a publicly traded company majority-owned by Harbinger Capital, appointed Omar Asali as acting president, replacing Harbinger founder Phil Falcone, who continues as chairman and chief executive.

DoD, DoT Say Hands Off L-Band

The U.S. Departments of Defense and Transportation declared their strong opposition to the LightSquared plan in a June 14 letter to the National Telecommunications and Information Administration (NTIA).

In their official statement, “The Departments continue to support the National Broadband Plan, but cannot do so at the expense of a global, ubiquitous utility such as the Global Positioning System. The Departments encourage further assessment of any alternative spectrum and/or signal configuration plans.” See

The Department of Homeland Security was conspicuously absent from the signatory line, as it has been in most public goings-on. Under pointed congressional questioning about its reluctance to enter the ring, a DHS spokesperson averred that the agency had been “carrying a lot of water.”

Javad Says End P-Code Encryption

To solve the LightSquared versus GPS controversy, Javad Ashjaee, president and CEO of JAVAD GNSS, has appealed directly to President Obama to discontinue the encryption of P-code, the restricted military GPS signal. “This policy is not helping national security. It is hurting both precision users and the broadband project. We need more broadband, for global, fast, and inexpensive real-time kinematic (RTK) GPS.”

IIF II Up, Up, and Away

The U.S. Air Force successfully launched GPS IIF-2 Space Vehicle Number (SVN) 63 aboard a United Launch Alliance Delta IV Medium rocket on July 16 from Cape Canaveral Air Force Station, Florida. This is the second in the series of 12 GPS IIF satellites that Boeing has on contract with the Air Force. Boeing reported the first satellite signals from space received within four hours. On July 20, stations of the International GNSS Service tracking network reported a signal from SVN63’s L-band transmitter. Testing will ensure health of L1, L2, and L5 signals beforethe satellite is turned operational; this is expected in August.

The satellite joins the GPS constellation of 30 operational satellites. SVN-63 will assume plane D, slot 2A, replacing SVN-24 after nearly 20 years of service.

The IIF satellites will provide greater navigation accuracy to users through improvements in atomic clock technology and a more robust signal for commercial aviation and safety-of-life applications, through the third civil signal (L5). GPS IIFs will have a longer design life of 12 years, and will continue to deploy the modernized capabilities that began with the modernized GPS IIR satellites, including a more robust military signal.

A Boeing statement concluded: “With safety checks completed, checkout will begin under the direction of the Air Force GPS Directorate. Checkout includes payload and system checks to verify operability with the GPS constellation of satellites, ground receivers, and the Operational Control Segment system. Boeing will officially turn over SVN-63 to the Air Force 50th Space Wing and the 2nd Space Operations Squadron this fall after the spacecraft completes on-orbit checkout.”

GPS III Design Review Completed

Lockheed Martin successfully completed on schedule a system design review (SDR) for the GPS IIIB satellite increment under the U.S. Air Force’s next-generation GPS III program. The company is under contract to produce the first two of a planned eight GPS IIIA satellites, with first launch projected for 2014. The contract, which features a “back to basics” acquis
ition approach, includes a Capability Insertion Program (CIP) designed to mature technologies and perform rigorous systems engineering for future GPS III increments.

The GPS IIIB SDR established requirements for the capability insertion planned for the follow-on GPS IIIB satellites and “validated the satellite design will meet the ever-increasing demand of more than one billion GPS users worldwide.”

GPS IIIA will deliver signals three times more accurate than current GPS spacecraft and provide three times more power for military users, while also enhancing the spacecraft’s design life and adding a new civil signal designed to be interoperable with international global navigation satellite systems.

GPS IIIB will provide higher power modernized signals, a fully digital navigation payload capable of generating new navigation signals after launch and a Distress Alerting Satellite System payload that relays distress signals from emergency beacons back to search and rescue operations.

Galileo Finds LS Interference

The head of the European agency overseeing Galileo filed an official FCC comment, expressing strong concern about the Lightsquared terrestrial signal. Analysis in Europe shows that LightSquared transmissions “have considerable potential to cause harmful interference to Galileo receivers.”

Video. Meanwhile, the European Space Agency has a video of Galileo in-orbit validation satellite assembly and testing. The first two satellites are destined to launch together at the end of October aboard a Russian Soyuz rocket, from the European spaceport in French Guiana. They will join two experimental satellites already on orbit. See video.

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