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Re: FO-29 users where are you?



----- Original Message -----
From: "Sebastian" <w4as@bellsouth.net>
To: "AMSAT BB" <amsat-bb@amsat.org>
Sent: Saturday, August 30, 2008 6:41 AM
Subject: [amsat-bb] FO-29 users where are you?

> It seems that most of the time when there is a pass in my area from
> FO-29, there are no users on the bird.  FO-29 is an excellent & loud
> satellite, and it requires very little output power.
>
> I just spent 10 minutes or so calling cq, and listening up and down
> the passband, and there is no one around.  It gets boring listening to
> myself on the downlink!  This is generally the case, no matter the
> time of day or night.
>
> Please, those of you who have the equipment - FO-29 is alive and well,
> let's use it!
>
> 73 de W4AS
> Sebastian
>
Hi Sebastian, W4AS

Over Europe there are many users of FO-29 but all of them are equipped
with low noise preamplifiers antenna mounted and good antennas.

By the way when FO-29 comes up at AOS it is very common to listen for
many stations trying to get back for their own signals back and fort all
over the pass-band without success because their receiving sensitivity is
low.

Since the FO-29 sensitivity is very high only a very low EIRP is necessary
to be translated with sufficient power for a decent QSO in SSB or CW
provided that the ground station sensitivity is adeguate as well.

Quoting many succesfull ground stations using FO-29 over EU it is possible
to state that for good operation all over the orbit from AOS to LOS a
minimum ratio G/T = - 2 dB is necessary.

As an example:

Antenna gain G = 13 dBi = 20 in power factor
Overall receiving Noise Figure = 0.45 dB equal to T= 31.6 kelvin

G/T = 20 / 31.6 = 0.63 and 10 log     0.63 = -2 dB
                                                         10

Another example:

In order to get about the same ratio G/T = - 2 dB and following the
above formula we see that it is possible to use an antenna with
G= 16 dBi = 40 in power ratio and a greater receiving system overall
Noise Figure = 0.9 dB corresponding  to T =  67 kelvin

And so on..........

Many years ago the recommended ratio G/T for every satellite was supplied
by AMSAT

The above G/T = -2 dB for FO-29 has been experimentally derived knowing
the working conditions of many succesful stations in QSO with me over
Europe.

73" de

i8CVS Domenico




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