All, I've been studying Hellschreiber screenshots to estimate multipath delay. Delayed echoes via the ionosphere show up in the pixels that make up the vertical part of each Hell mode character i.e., letters appear as though they were printed twice with one slightly above the other. The location of the secondary print depends on how long the delay is.
It's my understanding that each vertical axis pixel takes 4ms to print, so a delayed echo of the same duration should cause an additional pixel to appear just above the last one at the top of the character. An 8ms delay would print 2 pixel spaces above and so on. Audio editors should be able to reveal multipath echoe delay times with greater accuracy. Recorded Hell mode signals can be played back and observed visually to find characters that show multipath characteristics. The time difference between the "main" signal pulse and the delayed pulse can then be measured in ms. I understand the basic concept of how Hellschreiber works, but my interpretation of all this could throw-off everything I've just said ; ) Comments welcome... Tony -K2MO PS: Screenshots of any Hell mode QSO's that exhibit multipath characteristic, especially NVIS contacts, would be appreciated.
