[amsat-bb] Link Budget

[Paul Stoetzer]

It's about 20 dB more path loss to the moon than to geosynchronous
orbit. So if you need 5-10 watts of RF to a small dish for the
geosynchronous satellite, you'd need 1000w to the same dish or a much
larger dish to reach a transponder on the moon.

Not to mention the delay for a signal to the moon and back is 2.6
seconds compared to about 240 ms for a signal to and from a
geosynchronous satellite.

73,

Paul, N8HM

On Sat, Nov 7, 2015 at 3:00 PM, Joe <nss at mwt.net> wrote:
> oops I missed Now drop the same transponder on the moon,, and how much more
> is needed?
>
> Joe WB9SBD
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> On 11/7/2015 1:57 PM, Joe wrote:
>>
>> Can anyone here run a link budget for me?
>>
>> I'm in an  slight heated debate with some people, About how they have
>> heard about the possible Geo synchronous bird coming up, and they are all
>> wondering why don't "THEY" I like the "THEY" part, anyway why don't they
>> just put it on the moon.
>>
>> I gave them several reasons why a Geo bird is better,
>>
>> 1- It is there 24/7 where the moon is visible less than 50% of the day
>>
>> 2- the Geo bird doesn't move ( or extremely little) so set the antenna and
>> forget it. Where the moon requires tracking programs and antennas that can
>> move in AZ and EL
>>
>> 3- Useable "Window" The amount of the earths surface that can see either
>> is soo close to the same why bother I bet a geo bird would be at least close
>> to 90% of what the moon see's
>>
>> 4- And finally antennas and power required. The moon being soooo much
>> farther away the amount of power needed each way has to be MUCH more. And
>> thats what I was wondering say you had a nice decent transponder in Geo
>> orbit. what power levels say ERP I guess is needed each way?  then drop the
>> same transponder and how much more erp each way will be needed to have the
>> same level of contact quality?
>>
>> Joe WB9SBD
>>
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>
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
> are solely those of the author, and do not reflect the official views of
> AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb