The Icom IC-800 will work with some Doppler Error in Digital voice mode. I have been testing the IC-800 specifically to see how well it would work in theory with a 2-meter signal from a simulated LEO Orbit, such as ISS at 240 miles altitude. The results have been very promising on Earth.
The IC-800 will decode good Digital voice, with a frequency error of > 2.5 kHz. And this was at an indicated signal level of S1 on the radios S-Meter. At higher S-Signal levels the amount of frequency error the IC-800 can tolerate in digital voice mode is higher.
I setup a pair of IC-800 20 miles away. Then by using a combination of 5k channels on one radio and 6.25k channels on the other radio, i was able to simulate 2, 2.5k and 3k channel doppler errors. A beam antenna was used to Lower the indicated Signals levels until audio quality droped.
The lower the altitude the higher the Doppler (Frequency dependant too). The Doppler from ISS is approximately Plus and Minus 3.3 kHz. This means that If a LEO satellite is approaching on 2-meters, the frequency you will see on your radio will be up to 3.3 kHz higher for the first minute, then will quickly drop to zero Doppler for a few seconds at the 5 minute mark (assuming a 10 minute pass).
So, in theory, if the Doppler on a transponder based satellite is less than 3 kHz and you have signals stronger than 1 S-Unit, it should be possible for 2-way Leo satellite via digital voice. Anyone else have an IC-800 and want to test?
Miles WF1F
www.marexmg.org
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