I don't think it is feasible... for a cooling reason :)
Regards,
Javier
El 09/06/2011 22:18, William H. Fite escribió:
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<[email protected]> 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<[email protected]>
To: [email protected]
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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