[hpsdr] "Syllabic Squelch" for SSB Rx

[Michael Carey]

Interesting to hear you talk about this.

A HF SSB squelch/mute that operated on voice has been a feature on Codan 
HF equipment for a long long time.   The name Codan is an acronym, 
Carrier Operated Device Anti-Noise... a reference to the mute circuit 
they developed in the 1960's that kept their HF radios quiet unless 
someone was actually talking.

My Icom IC-F7000 (commercial HF) radio has a voice mute that seems to 
perform a very similar function.

HF radio was used extensively in the Australian "outback" in the days 
before the telephone arrived. The Royal Flying Doctor Service and School 
Of The Air were users of HF radio.  The voice operated mute in the Codan 
HF radios made living with a HF radio operational 24/7 in the household 
bearable.

When selcall on HF (CCIR 493.1) became popular in the 80's, the mute 
circuit was also able to keep the transmitted selcall tones muted as 
they fell out of the frequency range that the voice mute "looked for".

I've got Codan 6801 Mk2 service manuals with the schematic of their mute 
circuit.  If anyone wants I can scan the page and post a link.

Michael.
VK5ZEA

On 5/11/2013 10:47, Ken N9VV wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi,
> has anyone ever spoken about "Voice Operated Squelch" or "Syllabic 
> Squelch" for our SDR equipment?
>
> <URL: 
> http://www.ebay.com/itm/VOS-Voice-Operated-Squelch-Audio-Muting-Kit-Form-/321145239752
> >
>
> Old Kenwood gear had "Syllabic VOX" but you never hear a word about it 
> anymore. Could our SDR equipment accomplish this?
>
> 73 Ken
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