Hello Joe, Trevor,
my 2 cents:
There is for sure an interest for such a mode in the 472kHz and 136kHz
communities.
In november 2018 I designed an application that "revived" the slower JT9 modes
(JT9-2, JT9-5, JT9-10). Basicaly it just resamples the audio by 9/20 (for
JT9-2), 27/160 (for JT9/5) or 1/12 (for JT9-10) and the uses the JT9 decoder
(JT9.exe). See http://www.472khz.org/SlowJT9/ .
Over the past year it has been used on 472 and 136 kHz. The conclusion is that
JT9-2 is a very useful mode on 472 kHz and shows the more or less expected
improvement of 3dB over JT9. JT9-5 also works on 472 kHz, but most of the time
it will not achieve the theoretical 7dB improvement over JT9, probably due the
TX and RX stability issues. On 136 kHz stability is a lesser isue and JT9-10
signals have been copied across the Atlantic.
Based on this experience my suggestion for a specific MF / LF mode would be
stick to a 2 minute cycle mode and use "accumulative decoding" for further SNR
improvement. The SNR improvement will be less than 3dB for 2 cycle decoding,
but it should "bypass" the frequency stability problem.
73, Rik ON7YD - OR7T
________________________________________
Van: Joe Taylor <j...@princeton.edu>
Verzonden: zondag 23 februari 2020 16:35
Aan: WSJT software development
Onderwerp: Re: [wsjt-devel] LF/MF possible new mode ?
Hi Trevor,
On 2/23/2020 07:34, Trevor Smithers G0KTN wrote:
> Back last August/September there was a brief post about a new
> WSJT mode in the early stages of development by K1JT and K9AN designed
> specifically for 136kHz, 472KHz and 160.
>
> I thought it was to be based on JT65 (but it might have been JT9) and was
> hoped to be far more sensitive at the designated frequencies than current
> offerings.
>
> Is this still under consideration ?
>
> Trevor G0KTN
Nearly always we have ideas on the back burner.
A "better-than-JT9" mode for making QSOs on LF/MF bands is one example.
Most likely it would be more closely related to FT8 than to JT65 or JT9.
It would use longer transmissions and have a narrower bandwidth, and
would likely achieve threshold decoding sensitivity -30 dB or better.
No promises about when such a mode might be available for testing.
-- Joe, K1JT
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