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 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.