Ligado TLPS Plans Called Major Threat to PNT Services

Ligado's terrestrial broadband service plans are perhaps "the greatest current threat" to the position, navigation and timing universe, PNTAdvisory Board Vice Chairman Bradford Parkinson wrote Tuesday for GPS World. Such terrestrial transmitters "effectively become jammers" for some GPS receivers. He said the board is framing a response to the Ligado proposal. He said the company, meeting with the board in November, offered to reduce power in the 1526-1536 MHz band: That "sounds like a major move in the right direction," but the offer also raised new questions about what that would mean for increased tower density and how permanent those power constraints would be. He said the current proposal "is unacceptable" because of what it would do to many PNT applications, and the new power limit proposal would still violate the 1 dB rise in carrier-to-noise ratio -- the standard for tolerance interference measurement -- for many PNT users. He said if the FCC continues to consider the Ligado proposal, the agency should require it to deploy transmitters for real-world open-sky testing -- at the firm's expense -- to assess harms to PNT accuracy. Parkinson has been critical of the 1526-1536 MHz band plans (see 1706290043). The satellite company didn't comment Wednesday.