[Elecraft] K3: Voice pitch adjustment on SSB (fwd)

[Jessie Oberreuter]

      IIRC, there was a paper in QEX several years back on an algorithm for 
auto-tuning SSB.  In the mean time, the formant frequencies we use for 
different vowels are practically constants across both male and female 
speakers, so it should be easy for us to tune in SSB by ear.  That said, I'm 
often surprised at how easy it is to be off frequency.  Honestly, I think it's 
because we get used to the sound of thin or compression speech and then fail to 
ask ourselves if we're really tuned in.


On Thu, 14 Aug 2008, O. Johns wrote:

> Folks,
> 
> I read the web pages about ESSB, after seeing on the reflector that the K3 
> now supports it.  It struck me that even ESSB doesn't solve one big issue 
> with voice transmission: PITCH.  Tuning the SSB receiver changes the overall 
> pitch of the received voice.  Unless you have met the sending ham or at least 
> talked to him/her on the phone (or on AM!!), you have no real idea how high- 
> or low-pitched the voice really is.  One can only guess, and get a sort of 
> feel for what a reasonable tuning is.
> 
> One way to solve this may seem a joke, but it isn't.  Everyone should buy a 
> little 440 Hz pitch pipe, the kind used to tune musical instruments.  Then, 
> say, the net control could blow his pitch pipe at the start of the net and 
> all the listeners could blow their little pitch pipes while listening to net 
> control.  They would all then adjust their receiver tunings until the pitches 
> matched.  Like a shortwave orchestra tuning up.  (Of course, this might 
> violate the FCC rule against music on ham radio, but maybe not if the pitch 
> pipe was near a pure sine wave.  Then the signal transmitted by net control 
> would be just an ordinary CW signal, but at 440 Hz from the net control's 
> suppressed carrier.)
> 
> A refinement would be to build a pure 440 Hz tone generator into the 
> microphone preamps of radios.  Net control pushes a button while transmitting 
> and it goes out over the air.  The net members push another button while 
> receiving to produce a 440 Hz tone in their speakers along with the received 
> signal from net control.  Then the receiving operators adjust their receiver 
> tuning until the pitches coincide.  For the tone challenged among us, the 
> receiver tuning could even be automated, much like the K3 already does for 
> sidetone on CW.
> 
> This scheme came to me when I was adjusting the audio parameters on my K2.  I 
> had the K2 running into a dummy load, and was listening to it on headphones 
> plugged into a TenTec RX320D across the room.  Since the K2 was on a dummy 
> load, I tried whistling and was surprised and pleased to find that the PITCH 
> of my whistle didn't match the one I was hearing on the phones.  But I could 
> adjust the RX320D tuning until they did match.  Guarantee of zero beat and 
> realistic pitch in voice reception.
> 
> Doesn't seem that this would be too hard to do.  Maybe the K3 could even do 
> it in firmware?
> 
> 
> 73,
> 
> Oliver Johns W6ODJ
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