[amsat-bb] Re: Dumb question 9600 FSK
dave at w0dhb.net
Fri Nov 22 07:32:59 PST 2013
Thanks Gordon and others.
Is there any SDR software that supports the FCDP and will demod FM properly
for 9.6K FSK ?
From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
Behalf Of Gordon JC Pearce
Sent: Friday, November 22, 2013 2:36 AM
To: amsat-bb at amsat.org
Subject: [amsat-bb] Re: Dumb question 9600 FSK
On Thu, Nov 21, 2013 at 03:45:04PM -0700, David W0DHB wrote:
> What mode should your RX be in to receive the 9600 baud FSK telemetry
> downlink signals. USB, FM ??
It should be FM, and you must pick up the signal from before the audio
filter. You're looking for "flat unsquelched" in Motorola parlance ;-)
9600bps FSK is generated by modulating the carrier frequency with the
digital bitstream directly, after passing it through a filter to round the
corners off so it doesn't splatter. As such, the frequency response needs
to be flat from DC to whatever the passband of the IF filter is.
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