LightSquared, Inc., said in a filing with the FCC that a recent ex parte filing by the GPS Innovation Alliance had “several significant errors or incomplete engineering and technical points,” including what level of noise floor increase constitutes harmful interference and whether significant buffers are needed between GPS and terrestrial operations.

In a July 2 ex parte filing in IB docket 12-340, LightSquared took issue with the alliance statement in a June 19 filing “that an increase of 1 dB in the noise floor is the ‘definition of harmful interference.’ The Alliance cites no Commission source for this, but instead simply asserts it. The Alliance’s assertion that 1 dB ‘is the accepted interference standard worldwide’ is simply false.”

LightSquared also noted that “the Alliance provides a graph from an Aerospace study, arguing that it shows that GPS devices are more resilient to adjacent band power than other consumer devices. This graph shows that the best performing of three GPS devices was a Garmin GPS receiver. While the Alliance does not explain the reason for varying levels of resiliency, this result is consistent with the results seen in the testing performed by the Technical Working Group (‘TWG’) in 2011: many devices across all categories showed high levels of resilience and thus compatibility with terrestrial use of L-band.

“Thus, it is obvious that the capabilities and components exist for the GPS industry to build receivers that are resilient to overload, compatible with terrestrial use of L-band, and that industry best practices in this regard should be widely adopted. Such best practices are routinely used by manufacturers of cellular handsets, which, as a class, demonstrated very high levels of resiliency in TWG testing.”

LightSquared also disputed the suggestion of the alliance that a “band gap” and “duplex spacing” are needed to protect GPS devices from interference by terrestrial operations. LightSquared said that “’band gaps’ or ‘duplex spacing’ are irrelevant to receive-only devices – and irrelevant to what the Commission must consider when it examines GPS and terrestrial compatibility. Moreover, the duplex spacing/spectral separation mentioned by the Alliance is often less than the spacing that exists between LightSquared and the GNSS band.”

In a statement today, LightSquared spokeswoman Ashley Durmer said, “There are GPS receivers in market today that are compatible with wireless broadband in frequency bands adjacent to GPS.  And so if some devices do not suffer actual harm, then good engineering means no receiver should suffer actual harm and improvements in receiver resiliency fosters innovation and is ultimately good for consumers.”- Paul Kirby, paul.kirby@wolterskluwer.com