4G Broadband May Jam GPS

A company called LightSquared is building a 4G broadband Internet network in the US that will use 40,000 ground-based transmitters and a satellite to make a state-of-the-art open wireless broadband network. According to their news release, this open network will "unleash the full power of the mobile Internet, driving innovation in devices, applications, and services." LightSquared will offer network capacity on a wholesale-only basis to a variety of business partners. This sounds like a great way for mobile users to access the Internet anywhere they go. But there is a problem.

The GPS industry is warning that the proposed broadband Internet network could effectively jam GPS signals. GPS World says a study by GPS-industry stakeholders, including Garmin, determined the LightSquared network "will create a disastrous interference problem for GPS receiver operation to the point where GPS receivers will cease to operate (complete loss of fix) when in the vicinity of these transmitters." That", says the report, "will deny GPS service over vast areas of the United States." The industry told the Federal Communications Commission of the potential problem but the FCC approved the multibillion-dollar effort, which will carry 4G broadband throughout the country. They have, however, mandated that LightSquared works with the GPS industry to identify devices that might be affected and changes required to make them work.

The issue is the carrier frequencies LightSquared intends to use. The transmitters will use the L Band 1 (1525 MHz-1559 MHz), which is right next door to where the GPS frequencies of 1559-1610 MHz work their navigation magic. New testing that uses proposed transmitter filters proposed by LightSquared should be finished by the end of June but there's no indication what might be involved in filtering the affected GPS devices or what that might cost.

Would you be willing to pay for a filter modification to your GPS so that your Blackberry or iPhone can get high-speed Internet access more easily? The FCC seems intent on making this system available, even if it may add costs to GPS users, which includes airplanes. The actual changes and costs will be clearer in June after the new study is completed. Let's hope that the 4G transmitters can be modified to work with existing GPS units. If not, we may all be paying for this new "interloper" in the GPS band.

REFERENCES

http://www.avweb.com/eletter/archives/avflash/1830-full.html

http://www.gpsworld.com/gnss-system/news/gps-community-urged-contact-congress-regarding-fcc-proposal-10962

http://www.gpsworld.com/gnss-system/news/data-shows-disastrous-gps-jamming-fcc-approved-broadcaster-11029