[amsat-bb] Re: Lunar link budget

i8cvs domenico.i8cvs at tin.it
Fri Jul 3 07:27:35 PDT 2009

----- Original Message -----
From: "Howie DeFelice" <howied231 at hotmail.com>
To: <amsat-bb at amsat.org>
Sent: Friday, July 03, 2009 3:14 PM
Subject: [amsat-bb] Lunar link budget

 Hi Domenico,

I could be wrong but I think your budget is correct for a regenerative
transponder but for a bent pipe transponder we need to add the uplink noise
to the downlink noise where

C/N (total) = 1/((1/C-Nup)+(1/C-Ndn)) which in this case would be about 6.7

Still pretty good, but would probably be better even at the lower microwave
freqs. If we used PSK31 exlusively, even 2.5 KHz many simultaneous QSO's.

Howie AB2S

Hi Hovie AB2S

I agree with you and this is why I writes....................290 kelvin but
(probably more)

> The gain of the 2 meters antenna on the Lander is 3 dBd = 5.14 dBi
> Assume that the Noise Figure of the 2 meter receiver is 0.5 dB = 35 kelvin
> and the sky temperature as seen by the 2 meter Lander antenna looking at
> the earth is conservatively 290 kelvin but (probably more ).

At microwave frequencies where the gain of the antennas of the Lander are
higher and higher than 3 dBd and the antenna pattern is very narrow who will
automatically and precisely point the antennas toward the earth and who will
compensate the pointing to follow the libration movements of the moon ?

73" de

i8CVS  Domenico

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