How The FCC Plans To Destroy GPS – A Simple Explanation

Re:How The FCC Plans To Destroy GPS – A Simple Explanation by marshray on Wednesday February 09, 2011 @05:46PM (#2199705)

It's possible the LightSquared transmitters will be far more directional than the Garmin test gives them credit for. They may not run full power all the time anyway.

Regardless, it's generally the responsibility of the receiver to ignore signals in another part of the same band, and this is a different band entirely. Perhaps some receivers are built as cheaply as possible and don't have the best filters. If they all break, well, their customers should know not to trust that brand again. Any other policy amounts to no one ever being able to establish new radio service on its own part of the spectrum, on the theory that some other defective other equipment might fall over.

Personally, I think it's far more interesting the prospect of having a network of 20,000 steerable-beam transmitters approved for 15KW ERP each at 1.5GHz. 300MW is about half the output of a typical electrical power plant. If those were networked that could make one hell of an antisatellite weapon, phased-array radar illuminator, or maybe even an SDI-type directed energy weapon.

If the military isn't behind this, well they should be. <conspiracy theory>Maybe that's why the FCC is fast tracking it so much.</conspiracy theory>

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Re:How The FCC Plans To Destroy GPS – A Simple Explanation by jbri on Wednesday February 09, 2011 @06:56PM (#2199921)

It's the responsibility of the receiver to ignore signals transmitted at appropriate power levels, yes.

The receiver is not required to be overengineered to cope with transmissions vastly more powerful than expected - that's why limits on broadcast power exist in the first place.

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Re:How The FCC Plans To Destroy GPS – A Simple Explanation by marshray on Wednesday February 09, 2011 @07:09PM (#2199961)

OK I see it now. It looks like everything in that adjacent band had previously been designated space-to-earth.

I suppose it would be reasonable for an engineer to assume a receiver is not going to end up within a few KM of a 15 KW transmitter at those frequencies.

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Re:How The FCC Plans To Destroy GPS – A Simple Explanation by X-Istence on Wednesday February 09, 2011 @09:25PM (#2200410)

At high power you can overpower adjacent frequencies wether you have good band filtering on it or not. For example a 2 Watt FM transmitter at 100 Mhz can easily overpower radio's tuned to 95 Mhz just because of its power, even with the appropriate filtering.

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Re:How The FCC Plans To Destroy GPS – A Simple Explanation by marshray on Thursday February 10, 2011 @02:52PM (#2203401)

The internationally-agreed upon plan for the adjacent band was to have all the transmitters in orbit and all the receivers on the ground. So I don't think a 2W transmitter in orbit is going to overpower receivers in a different band.

40,000 of 15KW transmitters on the ground may be another matter.

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Re:How The FCC Plans To Destroy GPS – A Simple Explanation by wtallis on Thursday February 10, 2011 @01:24AM (#2201038)

Why would the military want an array of tens of thousands of low-power emitters when a few klystrons will do? 10+ megawatts pulsed output in a single L-band device is not hard to achieve, and much higher can be achieved if you're willing to accept the higher cost and shorter lifespans associated with running at higher voltages.

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Re:How The FCC Plans To Destroy GPS – A Simple Explanation by marshray on Thursday February 10, 2011 @03:02PM (#2203453)

Yeah, I dunno. How about

1. They can repurpose existing infrastructure with just a software change 2. Nobody has to pay for much out of their own budget or build it in anyone's back yard 3. Nobody has to declare it under any treaties or such 4. The system can receive as well as transmit 5. It's engineered and tested for continuous operation. There may even be excess capacity available almost for free 6. The system is massively redundant and supplies its own power and backup generators 7. More is better 8. Why not? 9. If it saves one child... 10. ... 11. Profit!

and so on. Just tossing out wild ideas here.

If only Nikola Tesla were alive to see this plan, he would certainly approve.

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