[600MRG] Thoughts on SlowJT9 testing

[Edward R Cole]

In summer of 2012 I ran ground-wave tests with Laurence in Wasilla 
(AK) about 70 mile path and the signals were rock-solid week over 
week with not more than about a dB variance (SNR was about 35 dB).  I 
was running 4w EIRP with a carrier.

If you can find a partner <100 miles with no intervening mountains 
you should see a similar signal for your tests.  I think ground-wave 
is probably reliable out to nearly 250 miles but I have no one at 
that range to test with.

73, Ed - KL7UW

At 05:41 AM 11/21/2018, N1BUG 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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73, Ed - KL7UW
   http://www.kl7uw.com
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