On 06/10/2011 06:42 PM, Bob Camp wrote:
Hi
The FCC (like most US agencies) has a mission to promote as well as
regulate. The promotion side is what drives them to allocate frequencies in
a way that you can reasonably produce gear. They have always come back years
later and tried to change things around. Every time, the same issues get
hashed over. Sometimes a change actually gets made, sometimes not.
What's surprising with the GPS impact here is that the usual conversations
are taking place a bit late in the process. The impact on legacy timing gear
is one part of a much larger issue here. Hopefully it does not get lost in
the back and forth. There's an enormous amount of gear out there that gets
timing off of GPS.
Blinding the receivers like that hurts both because antennas and
front-end isn't prepared for quite that interference, and simple 1-bit
receivers will be caught... so more dynamics will be needed for the 30
dB correlation gain to be of any use.
Correlation gain could be increased... with a massive replacement of
receivers as signal would change... oh and sats. Still the front-end
would require much more interference tolerance... and to some degree
this is against the military aspect, as they rely on being able to noise
out un-keyed receivers when needed. So the counter-measure becomes less
usefull when counter-counter measures is needed on a wide scale just to
do normal civilian business.
Raising the signal level in a band by, what was it? 70 dB suddenly might
be a little too steep a change. Also, it would rule out many hardware
approaches which have made GPS useful in so many places.
Cheers,
Magnus
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