JT-65 decoding discrepancies

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  • Updated 3 years ago
Every time a new version comes out I set up the old and new version to see if the new is an improvement in decoding. Since I have the 6500, four sessions are possible running on separate slices. I have determined that if I setup four slices [on the same frequency] and four JT-65 sessions [same version] there are differences in the decoded calls about 25% of the time. The missed calls are usually the weaker ones in the -20db range. However, have decoded signals in the -27 db strength now and then. Has anyone else tried this experiment.?
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Bill W2PKY

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Posted 3 years ago

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YV5WZ

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Synchronized time, use Dimension 4 www.thinkman.com  
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Walt - KZ1F

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I haven't heard dimension4 mentioned in decades. Isn't that SO 1980's before ntp became ubiquitous in the consumer setting? It very easy to set the system clock to an ntpd. Why are you using dimension4 at this point?
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YV5WZ

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Why? Simple: it was suggested by someone from flexradio community & Fixed my clock Sync problem

Greetings & 73's from sunny Maldives 

George
YV5WZ /  8Q
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Al K0VM, Elmer

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I could never get  windows ntp to update often enough to keep my clock in sync ( seconds per day with no correction) for WSJT. But Dimension4 does that easily enough.

AL, K0VM
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Chuck Zappala

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I've tried different time sync apps and found that Dimension4 seems to work the best. Lots of options and adjustments in the set up. 73 chuck ke7sa.
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Walt

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I got confused, you have one radio, and you have four JT65 sessions (same version)

So what versions of what are you comparing ?  I like JT65 an have an interest in what you are seeing.

Cheers
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Walt - KZ1F

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Bill, I didn't understand what you meant either. I'm thinking you meant two versions of the jt65 software?
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Bill W2PKY

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I started comparing old to new but discovered if 2 instances of the same version were started on separate slices there are differences in the decoded calls.
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Walt

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Ah !  Got it !   You were going to compare versions but you have found decoding differences with the same JT software version on on sep. slices.    Will have to try that out.  I am assuming you are using WSJT-X v1.5.0 as your decoder - please let me know if you are using dif. software than that.

Cheers
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Bill W2PKY

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Hello Walt- yes 1.5 also have the new 1.6.1 JTMSK which is fun on 6M. Would be interested to see if anyone else has the same result.
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Walt

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Bill,

I have been watching two slices on 20 meters and they pretty much track.  60 percent are the same signal levels, the others are within 1 db of each other, the 1 db advantage is not on slice A or B, but they both take turns being the 1 up.  Because of noise levels in the city, I cannot copy anything below -20db.

Not much help, it seems, but I do not see any real dif. between two slices.  And with my small screen I have no room for more than that.

Maybe someone else will find a difference that can be traced to a particular issue.

good luck and cheers
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Bill W2PKY

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Walt, thanks for trying. I have sent files to Joe T. so will see if he can provide any help.
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N7AIG

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First thing that springs to my mind is that the audio streams are not the same. At the low SNR levels that wouldn't be too surprising, because you probably can't achieve identical passbands on the different slices.

... but if you *can* achieve identical slices, then something is probably awry in their separate audio streams -- likely dropped samples in one of them.
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Bill W2PKY

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My slices are all set up the same with regard to bandwith and all the other settings. Using FAST agc slider all the way to the right. Did some more checking last night on 20M and the missed "Q"s were all weaker then -20. Have decoded -26 and -27db signals at times. The dropped "Q"s are not always on the same slice so maybe Steve can shed some light on the subject.
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Cal Spreitzer

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I never have the AGC slider all the way to the right!  I've found the magic of good decodes is having AGC-T adjusted no more than mid way and also your audio stream in DAX adjusted so within WSJT-X your receive level is about 30db during no-signal conditions.  My guess is with your AGC-T set full right, anytime a strong station comes on your going to loose the weaker ones.  There is a sweet spot for AGC that brings the weak signals out. 

Cal/N3CAL
(Edited)
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Rob - AG6RK

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I am currently using WSJT-X "V1.6.0-devel r5719" on Win7.  2 instances of WSJT-X running is assigned to its own CAT COM Port but both instances tack the same VFO setting from the active slice, was using TS-2000 and also tried TS-480 rig setting but no difference

I use a Windows batch file to start up both instances, one for 20m (Slice A, COM4, DAX1) and other for 17m (Slice B, COM5, DAX2):

    cd "C:\Program Files (x86)\wsjtx\bin"
    @start wsjtx --rig-name=20m
    @start wsjtx --rig-name=17m
    cmd /K

I can get successful simultaneous JT9&JT65 decodes on each slice but would like to assign CAT control of each instance WSJT-X to its respective panadapter independently.  This should allow independent frequency settings for each instance of WSJT-X

I was curious if anyone is struggling with this issue and any work-arounds found.  Ideally, it would be advantageous to have selectable COM ports per panadapter and/or slice.

73,
Rob - AG6RK
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Bill W2PKY

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here is a thread that discusses the limitations of the CAT command language: https://community.flexradio.com/flexr...

I use NO RADIO and VOX for multiple sessions.
(Edited)