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

[Javier Herrero]

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<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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