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Re: LF: SlowJT9 update (v0.9.10)

To: "[email protected]" <[email protected]>
Subject: Re: LF: SlowJT9 update (v0.9.10)
From: Rik Strobbe <[email protected]>
Date: Tue, 20 Nov 2018 14:31:59 +0000
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Thread-topic: LF: SlowJT9 update (v0.9.10)

Hello Andy,

the "power level" slider (at the right) is initially set to zero. Maybe that is the reason for no audio.

I agree that this is confusing, but I have done this for safety reasons (I don't want have any transmitter "blown" because of a too high audio level).

73, Rik  ON7YD

Van: [email protected] <[email protected]> namens Andy Talbot <[email protected]>
Verzonden: dinsdag 20 november 2018 15:24
Aan: [email protected]
CC: rsgb_lf_group
Onderwerp: Re: LF: SlowJT9 update (v0.9.10)

I just tried installing this 0.9.10 version  on my Dell Inspiron laptop Win-10.  I set the soundcard correctly to  "Speakers / Headphones" and Tx tone to 1200Hz ,  hit enable Tx then  the 'Tune' button.   It shows as transmitting but there's no audio tone.     WSJT-X and other datacomms packages are working fine, both before and after trying

Normally don't get any issues like this with the default (the only) soundcard present.

I'll test on my other two PCs,  an HP Desktop with Win 7 and HP Notebook

On a different matter, I'll be writing this up in the next RadCom "Data" column (February's)   Could you summarise the baud rates and frequency shifts finally settled.   There has been so much discussion and changes I lost track and haven't followed the latest version

On Tue, 20 Nov 2018 at 13:50, Rik Strobbe <[email protected]> wrote:

Dear all,

I just uploaded a now beta-release of SlowJT9 (v0.9.10).

The changes are

JT9-2 and JT9-5 parameters changed to the original ones. The slightly slower baudrates make better advance of the transmission cycle. In theory this should improve S/N by 0.46 dB for JT9-2 and 0.74 dB for JT9-5.

Be aware that due to the baudrate changes there is NO BACKWARD COMPATIBILITY for JT9-2 and JT9-5. 
In other words: JT9-2 and JT9-5 send with v0.9.10 cannot be decoded with prior versions (v0.9.00 - v0.9.03) and vice versa.

The JT9-1 mode however is still the same and can be sent / received with all versions (and is WSJT-X compatible).

- JT9-10 mode (10 minute cycle) added, for the fearless.

I briefly tested v0.9.10 for in JT9-2 mode and it seems to decode (at least) at the same level as for the previous versions. But to determine a difference of 0.4dB, more extensive tests are needed.

The sole purpose of this version is to determine how JT9-2, and eventually JT9-5, behave in relation to the previous versions, so we can decide wether SlowJT9 will proceed with the original parameters (anno 2013) that imply an odd baudrate ratio between the JT9 submodes or my previous parameters, with "round number" ratios. 

Therefore all test reports, remarks, suggestions and opinions are most welcome.

For the same reason no other changes are applied.

Whoever is interested can download the SlowJT9 installation file at

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.

73, Rik  ON7YD - OR7T

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