By Stephen Longden, SBD ITS and Telematics Specialist
The navigation industry in the US has been put in turmoil by proposals by LightSquared to deploy a network of 40,000 transmitters for its nationwide wireless broadband communications network. These transmitters operate in the L Band spectrum also used for GPS positioning signals.
Garmin and Trimble have joined forces to warn the Federal Communications Commission (FCC) that the LightSquared plans “will create a disastrous interference problem for GPS receiver operation to the point where GPS receivers will cease to operate when in the vicinity of these transmitters.”
Tests performed by the navigation industry in January indicate that automotive navigation devices experience a jamming effect 5.7 km from a LightSquared transmitter and lose location fix 1 km from the transmitter.
In November 2010, the FCC gave LightSquared permission to use the spectrum and says it is confident that LightSquared can resolve any interference issues before a deadline of June 2011. However, the US GPS Industry Council is not convinced and warns that the broadband service “will have a severe impact on the GPS band.”
All automotive telematics and navigation systems and services in the US depend on reliable access to GPS signals. Any interference would have huge safety and economic impacts. The FCC is attempting to reach a solution by encouraging LightSquared and the GPS Industry Council to establish a joint working group. It remains to be seen how successful this strategy will be in reducing the severity of any interference problems as and when the LightSquared network is deployed.
LightSquared plans to provide a nationwide wireless broadband service through a combination of terrestrial transmitters and SkyTerra communications satellites for remote regions. GPS uses the 1559-1610 MHz band while LightSquared uses the adjacent 1525-1559 MHz band. These signal interference issues will be monitored closely by Europe and China as they push ahead with developing their own rivals to GPS through Galileo and BeiDou respectively. These regions will be looking to avoid any pitfalls already encountered by the US.