HF D-STAR anomaly

  • 2
  • Problem
  • Updated 2 years ago
I just installed ThumbDV on my Flex 6500 and am having some difficulties.  I followed instructions for installing SmartSDR for D-STAR and the D-STAR waveform.  Flex recognizes the ThumbDV, can put it in D-STAR mode and I can decode headers from every station received.  However, when I key up the transmitter, the D-STAR waveform appears.  As soon as I modulate, the waveform disappears and only a carrier remains.  If I unkey the transmitter and rekey, the waveform appears for a few ms and disappears.  If I uninstall the waveform, unplug the ThumbDV, plug it back in the Flex, restart SmartSDR, and restart SmartSDR for D-STAR, I can restore the transmit waveform until I modulate and then it disappears.  I have yet to decode any voice transmissions  (I am aware of the high signal required for successful voice decode).  I have done this reset routine many times with always the same result.  I have even switched USB ports on the Flex with no difference.
Many thanks for any suggestions

73, Bob, KN4HH
Photo of Bob  KN4HH


  • 97 Posts
  • 21 Reply Likes

Posted 2 years ago

  • 2
Photo of MikeE


  • 17 Posts
  • 5 Reply Likes
Hi Bob,

The D-Star demodulation issue has been going on for several months now. It doesn't matter how strong the signal is the D-Star waveform won't decode the audio, but will decode the headers. I believe Flex is aware of the issue. I have been waiting for the fix too.

I also have a UHF transverter connected to the Flex that sits a few feet away listening to a DV-Mega D-Star hotspot. In D-Star mode I hear an occasional burp from the decoder audio then nothing and can decode the headers just fine. I suspect there must be an issue in the D-star waveform. In my opinion this should be an easy fix.