An official of LightSquared, the company that has been under fire for its plan to offer mobile satellite services that could interfere with Global Positioning System signals, told a gathering at the 2011 National Marine Electronics Association's International Marine Electronics Conference & Expo that solutions were in the works to prevent disruptions from occurring.
“Our integrated network will bring great benefits to wireless users nationwide, but at the same time we’re committed to ensuring this service doesn’t interfere with any GPS devices. We’re eager to work through any issues,” LightSquared vice president of spectrum development Geoffrey Stearn said at the event, which took place last month in Fort Myers, Fla.
Although the LightSquared frequencies don’t overlap with those allocated for the Global Navigation Satellite System, which includes GPS, they are immediately adjacent. In radio transmissions such as these, there are always emissions that stray out of the allocated band and intrude on neighboring frequencies. The fear is that LightSquared’s transmissions will drown out GNSS signals because they are far more powerful, the NMEA said in a statement.
“It was a surprise to us that there would be a [GPS] receiver overload,” Stearn said. He also said that, based on data the company has collected, “we’re offering mitigation steps that we believe will solve the issue and will ensure our operation will be compatible with people’s continued use of GPS.”
LightSquared has proposed the use of filters in GPS receivers, along with power levels that the company said won’t interfere with GPS. It also agreed not to operate in a 23MHz band immediately adjacent to the GPS band, at least for now.
“We still have licensed rights to the upper band channel,” Stearn said. “We’re not giving it up, but gave control to the FCC. We won’t operate there until the FCC says it’s OK.”
Several people who attended the LightSquared session later expressed concern that the 23MHz guard band is temporary and that the company will eventually want to use the entire band, maybe at full strength.
In addition, although GPS manufacturer Javad GNSS has developed a filter design that may take care of the problem, electronics experts said the industry needs to thoroughly test the design.
“This is an extremely important issue for our members, as well as for anyone who relies on GPS, which is just about everyone,” NMEA interim executive director Bruce Angus said in a statement. “We thank Geoff Stearn for coming to the conference and expo to discuss the problem and LightSquared for its commitment to avoiding disruption of the GPS system. We’ll be watching the resolution of this potential problem very closely.”
Look for additional coverage of this topic in the November issue of Soundings Trade Only.