Besides GPS, LightSquared also Interferes with Satcom
While the LightSquared broadband wireless network’s potential to disrupt GPS signals has been widely publicized, a lesser known problem is the potential of the system’s high-power transmitters to interfere with satcom. An RTCA special committee is defining a new antenna diplexer specification with filtering necessary to prevent LightSquared base station transmissions from interfering with the reception of Inmarsat aeronautical service in the same band. Also addressing the issue is Arinc’s air-ground communication system subcommittee, which is “monitoring the situation closely,” said Arinc airlines electronic engineering committee executive director Paul Prisaznuk. However, “no AEEC diplexer standards will be developed until LightSquared interference issues are resolved to the airlines’ satisfaction,” he said. Inmarsat and LightSquared are among parties participating in the RTCA process, stemming from their December 2007 cooperation agreement to re-band and reuse L-band spectrum covering North America. The potential of satcom interference does not cause the same level of concern as GPS interference, “largely because there has been a longstanding process to develop the standards for diplexers on this,” said Jeff Carlisle, LightSquared executive vice president of regulatory affairs.