[amsat-bb] going digital

Simon Brown simon at sdr-radio.com
Sun Jul 20 13:13:33 UTC 2014


If both side have good Doppler correction then it can be done, but you have
to choose the correct mode as there are other issues even if the Doppler
correction is perfect, especially when the range is changing at its maximum,
for example as the satellite passes overhead.

Simon Brown G4ELI

-----Original Message-----
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of John / NS1Z
Sent: 20 July 2014 11:46
To: Phil Karn; Paul Stoetzer
Cc: amsat-bb at amsat.org
Subject: Re: [amsat-bb] going digital

Is there some reason why a digital signal cannot be passed thru an
analog/linear transponder? What goes in is what comes out. It seems the lack
of transponder bandwidth limits the digital signal experimenter...
Maybe that is why commercial transponders on satellites are linear. They can
take any modulation and retransmit it : AM, FM, PM or CB

The biggest problem would be the taxi-cabs etc

-----Original Message-----
From: Phil Karn
Sent: Saturday, July 19, 2014 4:24 PM
To: Paul Stoetzer
Cc: amsat-bb at amsat.org
Subject: Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin - AMSAT
Fox-1C Launch Opportunity Announced

On 07/19/2014 12:28 PM, Paul Stoetzer wrote:
> Are FM repeater satellites what we all want in orbit? No. Personally, 
> I'd like a Mode J linear transponder in a sun synchronous circular 
> orbit of about 2,000km (if we can't get anything to HEO).

Getting a launch opportunity is difficult and expensive. Going digital is

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