LightSquared shows GPS interference fix

A $300 antenna would keep GPS receivers from being affected by its LTE network, the carrier says

LightSquared and a partner, Javad GNSS, showed off a filter and an antenna on Thursday that they said would solve the anticipated GPS interference problem that has plagued the carrier's plan to deploy an LTE network in frequencies near those used by GPS.

At a live news conference in Washington, D.C., that was webcast, the companies showed an external antenna roughly the size of an enterprise Wi-Fi access point and a ceramic filter smaller than a pencil. Javad would make the filter and incorporate it into the antenna, which would cost US$300 or less and could be easily swapped with external filters on receivers in the field, the companies said. Retrofitting receivers with internal antennas would cost about $200 each, according to LightSquared.

The companies had announced last month that they had a solution to the anticipated interference problem. On Thursday, they showed off the Javad products for the first time and LightSquared said it was working with three or four other companies on solutions. The carrier produced a letter from manufacturer Partron America, dated Tuesday, saying it had produced samples of an appropriate ceramic filter and could make it in volume on a month's notice.

LightSquared is facing fierce opposition to its plan to build a terrestrial LTE (Long Term Evolution) network in addition to its satellite mobile data system and sell services at wholesale. Many GPS vendors and users say the land-based network would drown out GPS signals and should not be allowed. LightSquared says the problem is caused by GPS receivers that can't filter out its licensed frequencies.

LightSquared has shifted its initial LTE launch out of one of its licensed bands in order to prevent interference with conventional GPS receivers, such as those used by consumers. The fix shown Thursday is designed to protect precision GPS, which is used for applications such as surveying and agricultural automation.

The carrier wants to commercially launch its network early in the second half of next year, beginning in Chicago, and build it out over the next three years. The U.S. National Telecommunications and Information Administration (NTIA) still wants to conduct further testing to determine whether the interference problem can be solved.

Javad has developed a filter that, in conjunction with other changes to GPS receiver antennas, could prevent interference on effectively all precision GPS receivers, according to the companies. The filter would cost only $6, they said. There are approximately 50 of the Javad filters available now for carrying out tests, said Javad Ashjaee, president and CEO of Javad GNSS.

LightSquared said GPS manufacturers, not users, should bear the cost of upgrading GPS gear to prevent interference with the new network. The company has pledged to spend as much as $50 million to cover the cost of modifying all federal government receivers. There are believed to be upwards of 1 million precision GPS receivers in use in the U.S., said Martin Harriman, executive vice president of ecosystem development and satellite business at LightSquared.

As they did last month, the companies held up Javad's solution as proof that the interference is not an unsolvable problem as many GPS backers have claimed. Instead, efforts to block LightSquared are aimed at protecting the interests of the GPS industry, they said.

"This is not a law of physics issue," Harriman said. All the components of Javad's solution are available off the shelf today, the companies said. "Smart engineering is what is needed to attack this problem quickly," he said. Javad said the idea that the interference problem can't be solved stems from a misunderstanding of a solution that he presented several years ago.

Stephen Lawson covers mobile, storage and networking technologies for The IDG News Service. Follow Stephen on Twitter at @sdlawsonmedia. Stephen's e-mail address is

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