Finalized Roberson Testing Proves LTE/GPS Coexistence, Ligado Says

Its tests of different GPS devices show manufacturers can build products that coexist with Ligado's LTE plans, Ligado said in a submission to be filed Wednesday in FCC docket 11-109. The filing was a final result of Ligado-commissioned testing of LTE/GPS compatibility, with the company echoing what it said early this year when it filed preliminary test results (see 1602250032): that consumer GPS devices won't be adversely affected by Ligado's LTE operations within power limits agreed to by GPS companies Deere, Garmin and Trimble (see 1602040015). Ligado also said the Roberson & Associates testing proves many industrial-use GPS device designs let them coexist with Ligado LTE, while others either won't be used near network facilities or can be cheaply retrofitted in advance. Ligado said the 12 consumer devices it tested kept baseline GPS position accuracy when in presence of Ligado operations and even with severely underpowered GPS signals only one showed any LTE interference. Tablet and smartphone testing showed no effects to their GPS operations, it said. The tests of industrial devices showed one manufacturer's devices were affected, though replacing the stock antenna with a filtered antenna solved the issue, Ligado said. The company also said another manufacturer's devices were affected by LTE operations in the 1526-1536 MHz band, but Federal Aviation Administration requirements likely will include power restrictions that would resolve that issue.