LightSquared Offers Solution to GPS Interference

Martin Harriman, LightSquared's EVP, Ecosystem, Development & Satellite Business delivered a presentation to the Space-based Positioning, Navigation and Timing (PNT) Meeting, briefly showing LightSquared's solution to the problem of base station interference to GPS reception.

The most convincing presentation, however, came from Javad Ashjaee, whose company came up with a fix for the interference. The American Surveyor describes Javad's presentation in the article Javad Ashjaee's LightSquared Solution Presentation at the PNT Meeting.

There are actually two issues with LightSquared interference to GPS. One is overload interference to the signals from the GPS satellite. That affects everyone, and LightSquared has come up with a temporary fix of avoiding spectrum use adjacent to the GPS band. The other interference issue is with the correction signals high-precision GPS receivers need to deliver results accurate enough for agriculture, construction and other applications. The fix here is to use the LightSquared network to provide the correction signals, rather than the current dedicated satellite link.

Filters are also part of the solution, and The American Surveyor article describes Ashjaee's approach to the problem. One is a $30 ceramic filter in the LNA, and the rest are four tiny 24-cent surface acoustic wave (SAW) filters. Ashjaee said his company will begin manufacturing "LightSquared-integrated" receivers in May 2012 using the LightSquared network for high-speed communication.

The PNT meeting did not cover consumer devices, only expensive, high precision GPS units, and it remains unclear how the problem of LightSquared interference to these receivers will be resolved if LightSquared were to use its entire 1,5 GHz MSS allocation for terrestrial communications.

Doug Lung

Doug Lung is one of America's foremost authorities on broadcast RF technology. As vice president of Broadcast Technology for NBCUniversal Local, H. Douglas Lung leads NBC and Telemundo-owned stations’ RF and transmission affairs, including microwave, radars, satellite uplinks, and FCC technical filings. Beginning his career in 1976 at KSCI in Los Angeles, Lung has nearly 50 years of experience in broadcast television engineering. Beginning in 1985, he led the engineering department for what was to become the Telemundo network and station group, assisting in the design, construction and installation of the company’s broadcast and cable facilities. Other projects include work on the launch of Hawaii’s first UHF TV station, the rollout and testing of the ATSC mobile-handheld standard, and software development related to the incentive auction TV spectrum repack. A longtime columnist for TV Technology, Doug is also a regular contributor to IEEE Broadcast Technology. He is the recipient of the 2023 NAB Television Engineering Award. He also received a Tech Leadership Award from TV Tech publisher Future plc in 2021 and is a member of the IEEE Broadcast Technology Society and the Society of Broadcast Engineers.