# Re: translator invertin and noninverting?

• Subject: Re: [amsat-bb] translator invertin and noninverting?
• From: "i8cvs" <domenico.i8cvs@xxxxxx>
• Date: Tue, 14 Jun 2005 19:52:33 +0200

```Hi Andy

Suppose to have a mode-B transponder with a down converter on board
of satellite receiving from 435.4 to 435.5 MHz and the LO is 424.8 MHz
than the IF will be 435.4 - 424.8 = 10.6 MHz and 435.5 - 424.8 = 10.7 MHz
Is evident that increasing the uplink frequency the IF frequency increases
as well and as well increases the doppler as seen by the satellite.
Now the IF from 10.6 to 10.7 MHz is routed to an up converter in the
satellite in wich the LO is 156.5 MHz so that 156.5 - 10.6 = 145.9 MHz
and 156.5 - 10.7 = 145.8 MHz
Is now evident that increasing the uplink frequency from the ground the
downlink frequency transmitted by the satellite decreases and the resultant
doppler as seen by the satellite in to an inverting transponder decreases as
well because it is subtracted and partially compensated in to the
up-converter.
With an inverting transponder if you want to receive USB in 2 meters you
must transmit LSB in 70 cm
If the transponder is non inverting the resultant doppler as seen on the
ground is greater because it adds in to the up-converter been not
partially compensated.

Best 73" de

i8CVS Domenico

----- Original Message -----
From: "Andy Brian" <briaandy@gmail.com>
To: <amsat-bb@AMSAT.Org>
Sent: Monday, June 13, 2005 9:40 PM
Subject: [amsat-bb] translator invertin and noninverting?

> Hi all,
>
> can anyone explain me, where is the differences between invertin and
> noninverting
> translators or linear transponders. I think, not so sure is in mixing
> with higher LO
> in input  than for inverting translator? Thanks!
>
> Regards Andy
> ----
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----
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```

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