RTTY Recording and Playback Using HDSDR and MMTTY

SUMMARY

A Perseus SDR receiver and HDSDR software was used to record 8
minutes of the RTTY portion of 15m during the 2013 WPX RTTY contest,
Saturday, February 9th, 2013, starting at 1909z.  The recording
captured all of the RTTY activity between 21.070 to 21.130 MHz, and
also some NCDXF CW beacon activity on 21.150.  The .WAV file is over
340 MB.

Most of the time I kept my 5 ele. 15m beam pointed towards the East
Coast, but occasionally I moved it towards Europe to see if I could
pick up some DX.  

USAGE INSTRUCTIONS

To play back the recording and connect it to MMTTY so that RTTY audio
can be decoded:

1. Download and Install HDSDR from http://www.hdsdr.de/

2. Download http://www.kkn.net/~n6tv/HDSDR_20130209.zip (215 MB), and
   unzip the .WAV to the HDSDR installation directory

3. Start playback by opening a Windows command prompt, then enter:
   HDSDR HDSDR_20130209_190933Z_21100kHz_RF.wav 
   (or Shft+right click on the .WAV file with Windows Explorer then
   select "Open With"->HDSDR.EXE)

4. Hover over any control in HDSDR to see what it does.

5. Set mode to USB (there is no RTTY mode in HDSDR)

6. Drag the edges of the audio passband (lower right) so that mark and
   space signals fit between the edges

7. "Tune" by dragging the blue tuning bar

8. Redirect playback from the PC speakers to the MMTTY sound card (if
   possible), by using the "SOUNDCARD" button in HDSDR as a test you
   can just have the mic. listen to the speaker

9. Using Virtual Audio Cable and the Audio Repeater program that comes
   with it, you can direct the output of HDSDR to a Virtual Sound
   card, then "Split" that output, one part to MMTTY and the other to
   the speakers, though maybe you can also do that with hardware.

10. You can also use CW mode, which allows easier tuning by clicking
    between the mark and space signals, but you have to press the
    "REV" button in MMTTY to get it to decode properly.

73,
Bob, N6TV
n6tv@arrl.net
2 June 2013 02:15 UTC