[amsat-bb] Yes, DStar can work on LEO,

[MM]

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

ka1rrw at yahoo.com




 
____________________________________________________________________________________
Now that's room service!  Choose from over 150,000 hotels
in 45,000 destinations on Yahoo! Travel to find your fit.
http://farechase.yahoo.com/promo-generic-14795097