[time-nuts] GPS interference and history...

[Mark Spencer]

Perhaps in the longer term (ie. next the several decades) moving away from the 
current wide band spread spectrum scheme to a higher power narrow band scheme 
might make more sense for GPS.    A previous poster mentioned the use of nuclear 
powered satellites to achieve higher transmit powers, given the benefits of GPS 
that option should not be entirely discoutned in my oppinion.


----- Original Message ----
From: Magnus Danielson <magnus at rubidium.dyndns.org>
To: time-nuts at febo.com
Sent: Thu, June 9, 2011 12:03:45 PM
Subject: Re: [time-nuts] GPS interference and history...

On 06/09/2011 07:29 PM, Burt I. Weiner wrote:
> For many years the FCC has not allowed FM broadcast stations within
> certain distances of each other where a 10.7 MHz frequency difference
> existed. Not exactly the same thing, but did show an understanding of
> what can go wrong as a result of good receiver front end selectivity. In
> AM and FM broadcasting there has also been required distances between
> 1st and 2nd adjacent channels, only partially because of overload issues
> but more so because of occupied bandwidth and overlapping. I'm not sure
> how much more it would cost to build GPS receivers with better front
> ends, but I'm sure it would've priced GPS devices out of the hands of
> many consumer level users. The FCC under the direction of Congress has
> made (allowed) some pretty stupid moves in the past bunch of years. In
> my opinion, the FCC has forgotten what their purpose is, and being run
> by attorneys has made the situation that much worse as there are very
> few attorneys that understand the un-revocable physics of the
> electromagnetic spectrum.

Regarding GPS receivers there today exist many different front-end approaches. 
In particular have single-bit and 1.5 bit samplers and direct samplers been used 
for many customer GPSes. The GPS receivers needed in E911 compatible phones is 
hardly done with lots of money, space and power-budget.

Bringing too quick shift of requirements onto the GPS receiver market would... 
well kill it. Some degradation would be tolerated.

Look forward to L2C and L5 capabilities to show up alongside Glonass L1...

Cheers,
Magnus

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