[amsat-bb] Re: fo-29
domenico.i8cvs at tin.it
Tue Mar 1 11:20:27 PST 2011
I forgot to say that a transponder like that of FO-29 is made "inverting" in order to partially compensate and reduce the total doppler effect on the ground due for the uplink and the downlink frequencies because both dopplers subtracts each other into the transponder mixers during the up and down frequency conversion so that the resultant total doppler effect on the ground receiver is the difference between the uplink doppler and the downlink doppler.
The reverse is through for a "non inverting" type transponder like for example the OSCAR-7 Mode-A transponder in wich you transmit USB in 2 meters and receive USB in 10 meters but the total doppler effect on the ground receiver is the sum of both dopplers.
In the OSCAR-7 Mode-A the total doppler effect even if it is the sum of both dopplers is very low because the 2 meters uplink and 10 meters downlink frequencies are both relatively low so that the transponder can be made "non inverting" without considebable problems for the satellite user.
----- Original Message -----
From: Kevin Deane
To: domenico.i8cvs at tin.it
Sent: Monday, February 28, 2011 4:43 AM
Subject: RE: [amsat-bb] fo-29
> From: domenico.i8cvs at tin.it
> To: summit496 at live.com; amsat-bb at amsat.org
> Subject: Re: [amsat-bb] fo-29
> Date: Mon, 28 Feb 2011 03:33:04 +0100
> Hi Kevin,
> The transponder of FO-29 is inverting and to receive correctly in USB on 70
> cm you must transmit LSB in 2 meters.
> 73" de
> i8CVS Domenico
> ----- Original Message -----
> From: "Kevin Deane" <summit496 at live.com>
> To: <amsat-bb at amsat.org>
> Sent: Monday, February 28, 2011 3:07 AM
> Subject: [amsat-bb] fo-29
> > so I know you all will laugh at me but what inverting means lsb down usb
> up is this correct
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