FWIW, PSK125R does not survive the Doppler disturbances on UHF. Olivia
or Contestia does. Therefore, the mode we have found works best under
the severe conditions of multipath, Doppler shift, Doppler spread, and
very weak signals is Contestia 16-500 at 30 wpm. the minimum S/N is
-12 dB, which is essential for weak signal UHF and VHF digital
operation as every dB of S/N we can get is important for weak signal work.
73 - Skip KH6TY
Skip,
Thanks for the info. The path simulator results seem to agree with your
observations on the high bands. I bet you have a fair share of
problems with aircraft Doppler? I've noticed multiple reflections from
multiple aircraft while monitoring VHF beacons. Spectrum analysis
reveals how great those Doppler shifts can be; the mixing of 2 or 3
multipath signals can play havoc with throughput. .
While it's not quite the same, we didn't get a chance to test on HF
today. Andy tried his best to accomodate (always there for us Andy), but
conditions weren't good between us on 80 meters. Tomorrows another day.
Thanks again.
Tony -K2MO
Tony wrote:
All,
I'll be QRV for digital mode testing this evening after 2200z (April 15)
till 0500z (April 16).
QRG 14108 / 3588 (+ / - QRM).
Modes of interest:
1. MFSK32 (Fldigi)
2. PSK250R (Fldigi)
3. MT63 1K (Fldigi)
I've created a test transmission that will send each mode in sequence
starting with MFSK32 and ending with MT63 1K (long iterleave). RS-ID
will be used to facilitate automated band switching. Fldigi needs to be
configured to do this:
Click CONFIGURE > IDs and UNCHECK RECEPTION DISABLES DETECTOR. This will
enable automatic band switching upon the reception of RS-ID. The RX-ID
located in the upper right corner of Fldigi's main window must be
checked (green light).
See you on Andy's sked page http://www.obriensweb.com/sked/
<http://www.obriensweb.com/sked/>
Thanks,
Tony -K2MO
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