The company and its proposed hybrid satellite-LTE (Long-Term Evolution) network came under sometimes harsh questioning during a hearing before the House Committee on Science, Space and Technology, with some members calling for a compromise solution to the conflict between LightSquared and the GPS (Global Positioning System) industry.

Tests earlier this year showed that LightSquared's ground-based network would cause major interference with GPS in the upper part of the company's spectrum. Debate is now swirling around whether the network could operate in its lower frequencies without causing problems. At the hearing, a LightSquared executive pointed to an amendment that the company added to its proposal on Wednesday, which he called a sign of its continuing effort to solve the interference.

The U.S. Federal Communications Commission (FCC) granted a conditional waiver to LightSquared earlier this year that would make it easier for the company to deploy a commercially viable LTE network using spectrum intended primarily for satellites. Those frequencies are close to the ones used by GPS, leading to interference that GPS backers say would be devastating for many services.

That impact would extend to weather forecasting, including hurricane and tornado tracking, because the satellites and ground-based systems used for those purposes rely on GPS, said Mary Glackin, deputy under secretary of the National Oceanic and Atmospheric Administration. In addition, the U.S. Geological Survey would have problems predicting floods, landslides and even volcanic eruptions because of equipment such as stream gauges that rely on GPS, according to David Applegate, associate director of natural hazards at that agency.

In addition to causing problems with the Federal Aviation Administration's next-generation air traffic control system, interference with GPS would probably affect emerging systems to prevent collisions in the rail system and highways, a representative of the Department of Transportation told the committee. An earlier FAA analysis reportedly had predicted nearly 800 additional deaths from air crashes if the network were built.