[Elecraft] [K3} [KX3] SSBT like CWT ?

[Wright, Robert]

This sounds like an interesting project.  It would seem that the technique would be finding the offset frequency that provides the best alignment of harmonics, which is what we naturally do by ear.  Not difficult, but would probably need a bit of tweaking to provide good real-time performance.   It would only be valuable if it was significantly faster than what we do manually.

It's good when projects are self-motivating.

73, Bob, N7ZO


-----Original Message-----
From: elecraft-bounces at mailman.qth.net [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Peter Lambert
Sent: Monday, February 04, 2013 9:25 PM
To: 'Erik Basilier'; Elecraft at mailman.qth.net
Subject: Re: [Elecraft] [K3} [KX3] SSBT like CWT ?

You are spot on, Eric

This is an algorithm I've contemplated writing many times.

Voice results from the vocal cords snapping together in the range around 85Hz.  The filter effect of the various cavities, throat, mouth and nasal are quite high Q and filter the harmonic rich vocal chord excitation to produce the voice.

If you watch an SSB signal on your PSK waterfall you'll clearly see the harmonics of the vocal chords.

I think a DSP algorithm that calculates the location of the carrier based on the separation between the vocal chords is a definite doable proposition.

It would give SSB the perfect clarity you seek.

Love to have a go at this (I do DSP).  Do you Elecraft guys want to have a go or interested in using it if I do it ? (I could probably do it as a piece of PC code that processes sound card input so you could evaluate it).
Doesn't feel like to be a difficult thing to do.

Cheers,
Peter VK4JD

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Erik Basilier
Sent: Tuesday, 5 February 2013 3:07 PM
To: Elecraft at mailman.qth.net
Subject: [Elecraft] [K3} [KX3] SSBT like CWT ?

At Field Day I have observed a number of operators operating SSB. I have noticed that there is a great variation in skill when it comes to tuning the RX to an SSB signal. Sometimes I feel that the op has it tuned all wrong and I almost want to grab the knob. Maybe different people's brains focus on different aspects of the sound when they tune the RX. Some people seem to want to tune for the best balance between highs and lows, when the HI CUT and LO CUT would do a better job. When I tune the RX, I believe that I am not trying to balance highs and lows, but rather trying to find some kind of harmony in the sound. If I were tuning in a piece of music from an AM BC station with the radio in SSB mode, clearly the harmonics of a musical note will not be harmonious if the radio tuning is off. If a voice is used for singing, it is like a musical instrument. If the voice is speaking, I believe the harmonics are still at play as with a musical note. This leads me to speculate that it would be possible to run an FFT on the received audio and determine by how much the RX tuning is off, just like with CWT. I am very fond of the CWT feature on the K3 and on the KX3. I wonder if it would be practical to add SSBT as a new feature.

 

73,

Erik K7TV

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