Posted on 02/15/2012 5:51:02 AM PST by lump in the melting pot
The Federal Communications Commission announced it had revoked its conditional approval for the controversial LightSquared national broadband network.
The proposed network was to use airwaves once reserved for satellite-telephone transmissions and had been given a conditional approval by the FCC last year.
The FCC’s move follows a statement by the National Telecommunications and Information Administration, which held that “there is no practical way to mitigate the potential interference [with GPS] at this time.”
LightSquared’s plans have been strongly opposed by users of GPS systems, which include the military and the aviation industry. The NTIA tests demonstrated that the company’s network, even in a scaled-back version, would interfere with GPS signals and systems.
LightSquared, a Virginia-based company that is controlled by Philip Falcone, a hedge fund manager, issued a statement on Tuesday saying that the testing of the network was “severely flawed” and that it “remains committed to finding a resolution with the federal government and the GPS industry.”
LightSquared blames the GPS industry for making devices that stray into adjacent airwaves, namely the spectrum that LightSquared was planning to use.
The company has been very vocal about the problems it perceives exist with GPS technology. In the company’s blog, Jeff Carlisle, executive vice president for regulatory affairs, wrote that it appeared that the GPS industry had become “too big to fail,” noting that “GPS manufacturers have been selling devices that listen into frequencies outside of their assigned spectrum band – namely LightSquared’s licensed band.” He continued on to say that “The GPS industry has leveraged years of insider relationships and massive lobbying dollars to make sure that they don’t have to fix the problem they created.”
Sorry, I didn't mean to portray myself as an RF engineer. My only claim to any knowledge about this subject is that I have an amateur radio license.
Long ago, I was involved in VHF repeater siting and maintenance, so I learned just enough to be dangerous...
In any case, perhaps we’ve seen the end of their full page WSJ ads claiming they “own” the frequencies in question.
Their product really had to be bleeding into the GPS bandwidth because this company's CEO is one of the ones pals.It is much, MUCH more a matter of the 'dynamic range' of just a ton of 'User Segment' gear (think: Garmins, Trimbles, Tom-Toms, and cell site reference receivers etc) than it is 'bleed-over' from the gear LightSquared was going to field ... engineers term or quantify it as the "3rd Order Intercept" (TOI) point".
Much more detail than I can give in one sitting can be found here: en.wikipedia.org/wiki/Third-order_intercept_point
The premise for years had been that the GPS spectrum was going to be protected ... that has been the basis upon which the engineering and 'link budgets' and dynamic-range requirements have been based.
... sure, a MUCH higher dynamic-range (and better IF filter for adjacent channel rejection of signals supplied to the demodulator) GPS receiver could be built, but at the expense not so much in dollars, but in size (additional higher-performance RF filters for instance) and battery consumption (higher Drain -current low-noise 1st RF amplifier stage and also a higher-LO injection mixer as well) ...
#1) On what basis?
#2) It isn’t the FCC’s responsibility
Sorry, I didn’t think the < /sarc > tag was necessary!
#1- Unhardened satellites.
#2- No.
In any case, you would do well as an RF engineer ... you recognize certain RF factors in RF engineering that a lot of ‘general’ engineers have little concept of. Practical field work has it benefits! 73’s
Sorry, I didn’t think the < /sarc > tag was necessary!Fail and fail.#1- Unhardened satellites.
#2- No.
#1) No specifics (that answer is what we call in industry 'hand waving')
#2) No ident of the actual responsible agency (perhaps you really don't know?).
No soup for you!
Have a good day.
The FCC’s job is not to ensure that GPS works, just that when it does that it works well with others and that others work well with it. They did their job by identifying that the new player would destroy GPS; the FCC, while powerful, cannot tell the Sun to stop emitting extreme solar events.
That's a valid analogy. What happens is that filters in the real world can never be perfect. You can try to have a filter that will exclude everything outside the GPS band, but a strong enough adjacent signal WILL leak through to your receiver. And when you are trying to listen to a satellite signal, it doesn't take much to overwhelm your reception.
Actually, I think that LightSquared does "own" the frequency band. But, they are only licensed to use it for satellite to ground transmissions.
The waiver granted them conditional approval to use it for terrestrial transmitters, as well. That's what was rescinded.
Every frequency band license has restrictions on the usage. The licensee can't use it however they choose, especially if it interferes with others.
‘twill be interesting to see how they monetize that.
They already have a satellite in the sky, presumably using that band.
LightSquared was formerly known as SkyTerra, and they launched a huge satellite in November, 2010.
http://www.upi.com/Science_News/2010/11/15/Biggest-satellite-antenna-launched/UPI-85811289871420/
But, now that the terrestrial network is no longer viable, I don't know how they plan to use the satellite.
Read this.
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