[time-nuts] From GPS World - Lightsquared has been given the goahead
Rex
rexa at sonic.net
Wed Feb 2 22:06:24 UTC 2011
On 2/2/2011 7:25 AM, jimlux wrote:
>
>
> I got the impression that it wasn't modeled, but was an actual field
> test of some sort. I'll have to go back and reread.
>
> But, it's possible that the consumer receiver has better multipath and
> interference rejection, if only because it's newer. Aviation stuff
> takes longer to go through the approval cycle, so it tends to lag
> consumer electronics in terms of technology adoption.
>
>
From the paper submitted by the GPS manufactureres to the FCC
http://www.gpsworld.com/gnss-system/signal-processing/lightsquared-jamming-report-11030
it seems they simulated the Lightsquared signal with test equipment and
made measurements in an anechoic chamber of effects on GPS signal
reception to a couple of popular GPS receivers. Using this data they
extrapolated real-world effects with path loss calculations. Ironically,
it probably wouldn't be legal or safe to make the jamming measurements
in a real, open space, environment.
The paper says the Lightspeed transmitters can be up to around 15 kW
EIRP in a band right adjacent to GPS. I would think filtering out that
signal to avoid overload would be a daunting task.
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