[GreenKeys] Tri-tone RTTY

[Harold Hallikainen]

Once again, I'm very impressed with what was done mechanically (in the
encryption mechanism).

The tri-tone system is interesting (and new to me). I could easily
implement this in the DSP TU ( https://w6iwi.org/rtty/DspTU2/ ). I suspect
the use of multiple tones instead of just using wide shift would provide
better performance in selective fading since we would not end up with just
noise for mark or space.

I might implement this in the DSP TU. I can run tests by transmitting test
content recording it on a websdr (I generally use KFS), then running back
through the terminal unit and checking for errors.

Thanks for the interesting idea!

Harold
https://w6iwi.org


On Thu, November 16, 2023 10:09 am, Nick England wrote:
> I just came across an interesting tidbit - in WW2 the German Lorenz SZ42
> encrypted 50 baud RTTY used three simultaneous tones each for mark and
> space - providing diversity to overcome fading
> *Mark* 900Hz, 1620Hz, 2340Hz
> *Space* 540Hz, 1260Hz, 1980Hz
>
> At the bottom of this page are some audio files to hear tri-tone and
> regular RTTY,
> https://lorenz.virtualcolossus.co.uk/technical.html
>
> Nick K4NYW
> Contributor, FWIW Dept.
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
>
>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>>>> https://teletype.net/gksearch
>>>> 2002-to-present greenkeys archive:
>>>> http://mailman.qth.net/pipermail/greenkeys/
>>>> 1998-to-2001 greenkeys archive:
>>>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
>>>> http://comcents.com/tty/greenkeyssearch.html
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to harold at w6iwi.org


-- 
Not sent from an iPhone.