With its investment from Sprint hanging in the balance, LightSquared has asked the FCC for a declaratory ruling to resolve the regulatory status of unlicensed commercial GPS receivers with regard to the carrier’s licensed 4G LTE operations in the 1500 MHz Mobile-Satellite Service (MSS) band.
In particular, LightSquared wants the FCC to declare that GPS receivers cannot be protected from operations in adjacent MSS bands, except for out-of-band emissions.
The heat is on at LightSquared. The declaratory ruling request comes after a widely reported deadline, Jan. 31, from Sprint to get regulatory approval and after verbiage was published in the National Defense Authorization Act of 2012 requiring the FCC to resolve military GPS device interference concerns.
Last fall, Gen. William Shelton, commander, Air Force Space Command, laid the groundwork for the legislation, testifying before the House Committee on Armed Services that test data indicated the LightSquared terrestrial network posed “significant challenges for almost all GPS users.”
Javad Ashjaee, president and CEO of Javad GNSS, a maker of GPS devices, stepped up this week to defend LightSquared and challenge the Department of Defense’s assertions that its high-precision GPS units would be degraded. Ashjaee even questioned the vulnerability of military communications equipment.
“If what they say is true, it is a military disaster,” Ashjaee said. “In the battlefield, military is subject to jamming by the enemy. Military equipment is supposed to work in this hostile environment, which is much more hostile than LightSquared.”
Ashjaee was originally called upon to defend GPS against LightSquared but after investigating the problem he decided the fault, instead, lay with GPS receivers. A month later, Ashjaee had designed and manufactured a GPS unit that would filter out the LightSquared signals.
Ashjaee’s company now makes a line of GPS receivers that are compatible with LightSquared and its previous products can all be upgraded to filter out the terrestrial mobile signals.
Gen. Shelton told the House Committee on Armed Services that it is not feasible for GPS equipment to be redesigned with greater filtering to mitigate the interference. “Even if this is possible, we believe it would involve substantial financial cost and likely degrade the accuracy of high-performance receivers, which is critical to many key GPS users,” he said.
Ashjaee disagrees. He notes that all GPS units in the field, which are tuned to the 1.57542 GHz (L1 signal) and 1.2276 GHz (L2 signal) frequencies, will eventually be upgraded to add the L5 signal (1176.45 MHz). With that upgrade, the new receivers can be outfitted with additional filtering.
“All the existing units in the field should be replaced anyway, with or without LightSquared,” Ashgaee said. “The triple-frequency receivers will work much better. All businesses will have to upgrade to the new, more efficient receivers.”