LightSquared vs. GPS: Beware of simple thinking

Incredibly, would-be wireless provider, LightSquared, is still tilting at windmills. It continues to waste everyone's time in a vain effort to transmit terrestrial 4G signals on frequencies adjacent to those used for GPS satellites. Anyone with a decent understanding of the real, analog world would have known this will never work, as we'll see in The Long View...
(by @richi )

For several years, LightSquared has been planning and building a hybrid terrestrial and satellite-based 4G network. However, about nine months ago, the FCC ordered the company not to use the terrestrial component of its service, for fear of interfering with GPS signals. Unsurprisingly, LightSquared then embarked on a campaign of indignant lobbying.

But, in my opinion, LightSquared was dead wrong to assume it could use those frequencies without stomping all over GPS. Alexander Pope was right: A little learning is a dangerous thing. And this is important, because GPS has become a piece of critical infrastructure -- essential to our way of life.

LightSquare's argument is that its transmissions aren't within the GPS frequency bands. So it opines that any interference is the fault of badly-designed GPS receivers, not of its transmitters.

It's a physical certainty; it's the nature of radio modulation. The only question is the degree to which you'll interfere with the GPS signal.

You see, in the analog world, the actual bandwidth of a signal is infinite. Of course, the vast majority of the transmitted energy is at and around the carrier frequency, but lower power "sideband" transmissions will extend far above and below the intended range. Theoretically, infinitely far, but in practice, they're irrelevant once they become quiet enough to merge with the natural background radio noise.

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