[600MRG] Thoughts on SlowJT9 testing

[Roger Graves]

Last night I ran JT9 Slow v0.9.10 on JT9-1 for a while. It decoded quite a few transmissions that WSJTx v1.80 did not, e.g. several of N1BUG. When both decoded, S/N's reports were either the same or 0.9.10 gave 1 or 2 dB better. This looked very promising for better decoding of JT9-1. Later, on JT9-2, it got what looked like continuous decodes of Neil and Laurence. Very promising results with the new version - Thanks Rik! Also, Neil reported that it would not work above +1300. I would be desirable to be able to do that to allow working above the WSPR sub-band with a 474.2 dial to avoid guys running JT9-1. 

73,
Roger, VE7VV

> On Nov 21, 2018, at 6:41 AM, N1BUG <paul at n1bug.com> wrote:
> 
> First I want to thank Rik for his work trying to bring back the slow
> JT9 submodes! I also want to thank everyone who has been helping
> with tests. I truly believe these modes can be helpful in making
> long distance QSOs on MF and LF. But first we have to prove this
> implementation is working as expected and useful.
> 
> I think it is difficult to know how well the slower submodes perform
> with the testing we are doing so far. It is all very subjective.
> 
> If we could find some stations within daytime range of each other,
> one of them having the ability to step transmit power in 1 dB steps
> I think we could do much better in testing. The idea is to start
> with JT9-1 and enough power to ensure decodes at the receiving
> station. The transmitting station steps power down in 1 dB
> increments, allowing a few cycles at each level to check decoding
> and the receiving station. Keep doing this until decoding stops or
> becomes intermittent. Record the transmit power.
> 
> Switch to JT9-2 leaving power the same. If it is now decoding again,
> keep stepping power down 1 dB at a time until it stops decoding and
> record that power level.
> 
> Switch to JT9-5 and do the same thing.
> 
> I think these tests would need to be done more than one day to
> ensure results are not affected by propagation or noise level
> changes. Any volunteers???
> 
> I can listen but I cannot control my transmit power accurately
> enough to be the transmitting station for such tests.
> 
> ***
> 
> I am trying to create local tests in a similar manner. I can put a
> lot of attenuation between my U3S exciter and the transmitting
> antenna, using the receiving antenna as normal. Yesterday I could
> get my signal to -27 dB SNR on JT9-1 mode. The problem is I do not
> have 1 dB steps to test with. I just purchased a pair of step
> attenuators which I hope will do what I want. It will take some days
> to receive them and verify the setup works. A lot can go wrong with
> a setup like this (unintended signal egress / ingress bypassing the
> controlled attenuation path). Careful evaluation of the setup will
> be needed. Stay tuned...
> 
> 73,
> Paul N1BUG
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