Hi Rik,
I do not know the symbol lengths for JT9 slow and I do not know how
it compares to WSPR about frequency stability requirements.
>From my experiment last winter I can say that on LF WSPR15 often
gets across the pond when WSPR2 cannot. Clearly for WSPR mode, 15
minutes is no problem. Of course, maybe it's different for JT9. It
was very interesting to see the success of WSPR15. That was what got
me started thinking about slow versions of JT9 again.
I would be more concerned about stability of my equipment. The
homebrew stuff is probably OK but the rather expensive transceiver
used to drive the TX converters has a terrible TCXO. I never had
much incentive to work on trying to fix it, but if JT9 slow becomes
popular and if it needs better stability this will give me all the
incentive needed! :)
Yes of course JT9-86400 for Stefan! ;-)
73,
Paul N1BUG
On 11/8/18 5:12 PM, Rik Strobbe wrote:
> Hi Paul,
>
> Adding even slower modes in the application is not difficult. But
> the slower we go the more stringent the frequency stability
> requirements are. For groundwave this is limited by the TX and RX
> stability, but for skywave propagation the mood changes of miss
> ionosphere could be nefast. 136 kHz might be better suited for
> JT-10 ot JT-30 than 472kHz. Stefan might be interested in
> JT-86400 (one message a day) for ULF ;-)
>
> About JT9 coding: for this I am using another exe file of the
> WSJT-X suite. It seems to work fine, both for free and structured
> messages.
>
> 73, Rik ON7YD - OR7T
>
>
> ________________________________________ Van:
> [email protected] <[email protected]>
> namens N1BUG [email protected] [rsgb_lf_group]
> <[email protected]> Verzonden: donderdag 8 november
> 2018 22:57 Aan: [email protected];
> [email protected] Onderwerp: [rsgb_lf_group] Re:
> LF: JT9-2 and JT9-5 mode application
>
> Hello Rik,
>
> I am very interested in this! Thank you very much for your work!
> Tomorrow I will download the program.
>
> I think we badly need these slow modes for the average LF
> operators (which is most of us at least on this side of the
> pond).
>
> If the beta tests are successful, would it be possible to add
> JT9-10 and perhaps even JT9-30? For trans-Atlantic QSOs I think
> these could be very helpful.
>
> How did you transmit JT9-2 signals for the QSOs? I can do that
> with my U3S but it can only send free text messages limited to
> 13 characters. It cannot send the packed messages normally used
> for QSOs.
>
> 73, Paul N1BUG
>
>
> On 11/8/18 4:29 PM, Rik Strobbe wrote:
>> Dear all,
>>
>>
>> a few months ago there was a short discussion about a
>> "revival" of the slower JT9 modes such as JT9-2 and JT9-5.
>>
>> These modes existed in early versions of WSJT-X, and had the
>> advantage of a better S/N treshold level, at the cost of
>> longer transmissions. But unfortunately thse modes were
>> abandoned in later WSJT-X version.
>>
>> As a result I raised this question in de WSJT-X developers
>> group, but there was no intention do implement these modes
>> again, as the focus was more on the (further) developing of
>> new(er) modes.
>>
>> Having a closer look at the WSJT-X source code I noticed that
>> the JT9 decoding was done in a separate executable and with
>> some assistance of Joe, K1JT, I managed to write an application
>> that used this executable for decoding.
>>
>> As this executable only decodes JT9 signals, not JT9-2 and
>> JT9-5, I had to use a lttle trick: speeding up a JT9-2
>> recording by a factor 2 results in a JT9 signal (at the double
>> frequency) that can be fed to the JT9 decoder. The same can be
>> done for JT9-5 (now speeding it up 5 times).
>>
>> Some tests showed that this way a JT9-2 signal could be copied
>> at a 2.5dB better S/N treshold compared to JT9(-1). Not
>> completely the theoretical 3dB, but 2.5dB can often be the
>> difference between a failed or successful QSO. JT9-5 hasn't
>> been tested yet.
>>
>> All this was done "manually" and it was rather time consuming.
>>
>> So I decided to write an application that I named SlowJT9. It
>> takes care of all the conversions and frequency shifts.
>>
>> Besides JT9-2 and JT9-5 it also supports JT9(-1) for
>> convenience reasons.
>>
>> Over the past weeks I tested the application in JT9 mode and
>> after more than a dozen QSO's I feel that it now time to
>> release a beta version.
>>
>>
>> Whoever is interested can download the SlowJT9 installation
>> file at http://472khz.org/SlowJT9/SlowJT9_setup.exe.
>>
>>
>> For now only a Windows version of SlowJT9 is available. But as
>> the used IDE has cross platform facilities it should be
>> possible to support other operating systems as well in the
>> future.
>>
>>
>> The aim of this beta version is: - To test if the application
>> is working properly. - To find out if JT9-2 and/or JT9-5 have
>> a sufficient S/N advantage over JT9(-1). - To find out if there
>> is sufficient interest in using these modes to continue the
>> project. Therefore all comments, bug reports and suggestions
>> are most welcome via the Blacksheep RSGB LF Reflector, Yahoo
>> RSGB LF Group or directly at [email protected].
>>
>> 73, Rik ON7YD - OR7T
|
