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

[William H. Fite]

I well recall the furor over Cassini-Huygens in 1997 but approval was
ultimately granted and, of course, the launch was without incident.  Since
then, New Horizons, Galileo, and Ulysses have been launched with far less
public outcry, despite the fact that all are powered by RTGs.  Arguably,
well-designed reactors could be even safer.

While I appreciate that sensitivity to nuclear power for earth orbit
satellites could be greater than for deep space vehicles, we may have to
agree to disagree on the feasibility of nuclear powered satellites.

On Thu, Jun 9, 2011 at 4:06 PM, J. Forster <jfor at quik.com> wrote:

> Ha!
>
> Nuclear power in space is poltically utterly impossible in the US. There
> is huge opposition to RTGs, never mind even the thought of reactors.
>
> Solar is not really practical either. The sun puts out about 1 KW/Sq.M in
> EO, and solar cell efficiency is <20%; so 10 KW needs 50 Sq.M of
> stabilized pointing cells.
>
> -John
>
> =============
>
>
> > 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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>
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