[time-nuts] lightsquared test in las vegas
jfor at quik.com
Thu Jun 9 17:48:10 UTC 2011
Could well be, but I know the system was severely constrained by satellite
design considerations. 30+ years ago, high power was simply not available
on orbit for long periods of time. The only real option is solar cells,
then as now.
> Hi John:
> It's my understanding the the GPS system was designed by the military so
> that the received signal is below the thermal noise. That means that if
> you look for it with a spectrum analyzer you will see noise. It wasn't
> untill the KAL007 shoot down that the goverment disclosed it's existence
> to prevent a similar thing from happening. The new GPS L5 "Safety of
> Life" signal is to make aviation safer. So it appears that the focus
> has changed from military to aviation.
> Have Fun,
> Brooke Clarke
> J. Forster wrote:
>> Perhaps not in the abstract, but on-orbit power is severely limited, and
>> you can't get more RF watts out of a transmitter than you put in as DC.
>> Can you imagine the uproar if every GPS bird had a 10 KW transmitter on
>> board, powered bu a nuclear reactor?
>> The low received power is a direct consequence of engineering of
>>> On the other hand, what can be said about the wisdom of engineers that
>>> designed a product that cannot withstand any interference from
>>> spectrum holders? It has been known for at least the last 6 years that
>>> LightSquared's predecessor was going to occupy that spectrum with a
>>> based system.
>>> Does the GPS world really have much to say about the interference if
>>> LightSquared keeps their transmitters clean and out of the GPS
>>> -Chuck Harris
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