When Air Force Space Command’s Commander, General Willie Shelton testified to the Senate that LightSquared’s high-powered telecommunications signal would degrade, disrupt, and deny the GPS signal, there was plenty of disagreement. Much of the disagreement was from LightSquared who had plowed plenty of investor money—about a billion dollars so far—into the effort and had lots to lose.
So now, the study is done and the finding confirms Shelton’s concern: LightSquared’s terrestrial signal will degrade, disrupt, and deny the GPS signal. For LightSquared, it’s all over but the crying.
LightSquared started out with a largely space-based (and low-powered) scheme, but went more terrestrial for cost and performance reasons. The fact their signal was adjacent to the GPS signal was…let’s just say that part of the architecture was not well thought through. How so?
…aviation users could effectively experience a blackout of GPS capabilities, particularly around densely populated areas, where LightSquared ground stations are expected to be spaced 400 to 800 meters apart (snip)
At altitudes of 3,040 meters and below, aircraft could not rely on GPS for navigation over the nation’s capitol, most of Virginia and Maryland, and significant parts of Pennsylvania and New Jersey (snip)
…police cars could not acquire GPS signals within 182 meters of a LightSquared tower broadcasting at the maximum allowed power of 15 kilowatts (snip)
Signals to ambulances and fire trucks were nullified within 304 meters of a tower.
And now for the LightSquared crying part:
There are no feasible options for mitigating LightSquared interference…outfitting all GPS aviation receivers with special filters to ensure they do not pick up LightSquared signals would take between seven and 15 years and cost an unknown but extremely large sum…[also], the filters would reduce receiver performance. (snip)
…modifying LightSquare antenna patterns and exclusion zones or operating at lower power levels, are not good solutions because they would require more ground stations to be deployed, increasing the aggregate power output (snip)
The only remaining viable solution… [is] for LightSquared to acquire the rights to another part of the electromagnetic spectrum.
Who will rule the day here, GPS or LightSquared’s billion dollar baby? Well, consider this:
According to the GPS Industry Council, a trade group, GPS represents a $22 billion investment by the federal government and billions of dollars more by end users to develop applications that serve defense, public safety and homeland security needs, as well as a range of industries.
So who’s the villain here? LightSquared, who had to know GPS interference would be an issue? The FCC who licensed the effort? Or is it GPS, which has become all things to all peoples at all times, resulting in a perhaps dangerous dependency on its space-based signal?
GPS has its own set of problems but getting government and industry unaddicted to it can’t be blamed on its inherent usefulness. Over to you, FCC and LightSquared…