Deere & Company recently revealed tests conducted with LightSquared’s GPS signal massively interfered with John Deere’s GPS receiver equipment. Deere receivers registered impact of and interference by the LightSquared signal as far away as 22 miles from a transmitter. As a result of discovering the interference, Deere notified the Federal Communications Commission (FCC) on May 26. The company contends it has found no practical technical solution to the problem.

According to, “The U.S. military conducted anechoic chamber tests at a White Sands facility and open-air tests at Holloman Air Force Base in April. The tests, which simulated various cellular base station transmission schemes proposed by LightSquared in L-band frequencies between 1525-1559 MHz, without exception demonstrated severe interference to Deere’s high-precision GPS receivers.”

The issue was a concern to the precision agriculture industry even prior to Jan. 26, 2011, when the FCC issued an Order and Authorization giving LightSquared conditional approval to build out a ground-based wireless network. LightSquared Subsidiary LLC is a company that plans to provide a wholesale, nationwide 4G-LTE wireless broadband network integrated with satellite coverage. LightSquared will combine existing mobile satellite communications services (formerly known as SkyTerra) with a ground-based wireless communications network that uses the same L-band radio spectrum as the satellites.

Most of the GPS community is concerned that LightSquared's ground-based transmissions will overpower the relatively weak GPS signal from space. Although LightSquared will operate in its own radio band, that band is so close to the GPS signals that many GPS devices could pick up the stronger LightSquared signal and become overloaded or jammed. Some are also concerned that the FCC may approve a technical solution to the problem that requires millions of existing GPS users to upgrade or replace their devices. The build out has the potential to impact precision agriculture, emergency, transportation and defense systems that rely on GPS technology, it has been claimed.

Under the FCC order, LightSquared has until June 16, 2011, to run tests on potential interference and report back to the FCC its findings. Independent of the LightSquared tests, the government is conducting its own tests.

In addition, a coalition has formed—“Coalition to Save our GPS”—and is conducting a letter campaign to Congress to ensure that the GPS signal is not degraded in anyway. An FCC decision is not expected immediately after the June 16 report is filed, and the timeline for a ruling is not known.

To read more about the recent tests, click here.