John,Thanks very much for the reply and detailed summary of QRSSn. I had no idea that QRSSn could refer to anything other than CW! That’s really fascinating and I thank you for taking the time to write up the myriad details here, for me but perhaps also for others reading this board who may not be experts in this area (i.e., other old-fashioned self-taught “headphones guys” like me).
For the very small increment FSK versions of QRSSn, I agree, I would not have detected a few Hz shift in audio tone alone. But armed with this new knowledge, I will try something new. I have found I can aurally detect phase shift modulation if I zero beat a carrier against my transceiver’s 700 Hz key down sidetone (I use 700 Hz instead of the default 800 Hz due to some high frequency hearing loss). A good example is the French time station on 162 kHz, which unaided just sounds like a straight carrier. But zero beating that carrier tone (at 700 Hz) against the 700 Hz key down sidetone, I can hear the QRSS1 phase modulation overlaid on the “beat signal” between the two 700 Hz audio tones. It’s hard to describe what it sounds like but clearly something is happening every second. A “normal” unmodulated carrier does not do this. So, the next time I hear a carrier I suspect (or know) is using QRSSn, I’ll give that a try.
Thanks again for your very informative reply John. Very educational!
Bruce