To the puzzlement of the GPS community and independent radio propagation experts, the FCC ruled on September 13 that LightSquared should conduct further tests of its signal transmissions on its alternate, lower L-band frequency farther removed from the GPS frequency. Tests on a LightSquared frequency closer to GPS earlier this year produced extreme interference. The puzzlement arises because GPS engineers and propagation experts had already agreed that the alternate frequency–the second in a pair owned by LightSquared in the L-band spectrum–would produce almost equally poor results, and would be particularly disruptive to precision GPS receivers. While relatively few tests were performed on the alternate frequency, the specialists are certain that more tests would add little to what they already know. “We’ve been there, done that,” said one.
In Washington, an FAA observer speculated to AIN that the FCC really had no choice in making its decision, however unrealistic it appears. “They couldn’t say that LightSquared must move out of L-band completely, because that would force the company to buy very expensive frequencies outside L-band that it might not be able to afford within its current financing. On the other hand, there are political interests that are telling the FCC to find some way out of this dilemma, because the company cannot be allowed to fail. So call this a stop-gap measure which may last a while.”
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