[amsat-bb] Improving intelligibility on FM satellites

[Ronald G. Parsons]

I have investigated increasing intelligibility of the FM satellites as received by my Flex-6500. At first I suspected the demodulation by SmartSDR. This was tested by paralleling the downlink transverted signal to the Flex-6500 and to an Icom IC-R8500. 

Tests showed no significant difference between SmartSDR NFM (11 kHz) and R8500 FM (12 kHz) The NFM has better intelligibility than FM (16 kHz) for SmartSDR both uplink and downlink.

However, a significant improvement was obtained by adjusting the RX EQ in SmartSDR to match my speakers and ears.

An easy and cheap fix and it applies to whatever speakers and radios you are using. The link below shows the EQ I am using.

https://drive.google.com/file/d/0B-Jez46MB5RaVXBMeFNBYU5wRWc/view?usp=sharing

Ron W5RKN