[amsat-bb] Re: Dumb question 9600 FSK

[Gordon JC Pearce]

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.

-- 
Gordonjcp MM0YEQ