JT65 + JT9 simultaneous decode prob

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Hi,

I have been mostly working JT modes since getting my Flex a couple of months ago. I have been using WSJT-X 1.3. Tx and Rx filters set 0-4000Hz.

It had always puzzled me that I had never decoded a JT9 signal when in JT65 + JT9 mode. A few days ago I saw a stonkingly strong (to use an English colloquialism) JT9 signal and still did not decode it.

After running some tests, I can only seem to decode JT9 signals when WSJT-X is in JT9 exclusive mode and my receive bandwidth is reduced to 2KHz and placed in the JT9 sub-band.

The signal I mentioned above got a signal report of +1 when I managed to decode it. The DAX Rx levels and those in WSJT-X were not changed at all during my tests.

What am I doing wrong? At the moment I don't know if this is related to WSJT-X or the way I have got the Flex set up.

Mni tnx.
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DrTeeth

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Posted 5 years ago

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Larry Loen WO7R

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If you are using Digi-U, check you bandwidth.  The usual "buckets" do not go high enough to "reach" the JT9 subband.  You might try manually "stretching" the upper range of the frequency to reach it.  I find that regular USB works just fine in my setup (not sure why, but it works) and it has more bandwidth, needful for JT9.
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Pat - WH6HI

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Remember a couple of points.  RX BW is stored in the Global profiles.  The Transmit BW is stored in Transmit Profiles.  So be sure build a profile in each and also to have the transmit profile as part of the Global, because the selected transmit profile will be in the Global profile. 

Pat
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DrTeeth

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Apart from an initial error on my part, all settings are correct as all have suggested, including the Rx & Tx BW you mentioned. I can turn JT9 decoding on and off like a light switch. Please continue to suggest anything else, no matter how obvious it may be at the time as I have not ruled out operator error.
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Ed, K0KC

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Guy,

You should definitely set your receive and transmit bandwidth to 4000 Hz or greater (I use 4200 Hz) as Larry suggests above. Use DIGU as that bypasses any audio processing such as equalization that you do not want for the digital modes. Also, check the location of the blue vertical line on the "Graph". The JT9 decoder is only active above the frequency indicated by this line. I normally set mine at 2500 Hz unless I see a signal that I want to decode at a lower frequency.

I do not think you have a Flex problem.

Ed, K0KC
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George Molnar, KF2T, Elmer

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Is the seperator line in the wide view properly set to partition the waterfall properly? To the left, all signals are treated as JT65; to the right all are applied to the JT9 decoder.
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DrTeeth

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Hi Guys,

All is set present and correct as suggested by all of you above.

The blue separator line in the graph is set to the default 2500.
Using Digi-U.
Tx width is 0-4000Hz
Rx filter width is 0-4000Hz.

These have been my settings since I first started and are not recent changes at all.

I am about to try the 1.4 RC2 release as I have heard that the decoders are significantly improved but I would like to get this issue nailed first.

Thanks

OT bit - Not that I think it is related, but as I have the experts on board, do you chaps recommend AGC on or off?
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David--NV0O

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Several of us FLEX6*** users had problems with CAT control with the WSJT-X 1.4 RC2 release. These issues have reportedly been fixed in 1.4 RC3, which has not been posted to the WSJT site yet.
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DrTeeth

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I have heard that it works fine when configured as a TS-2000 and this is even required with RC3 AIUI.
(Edited)
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David--NV0O

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For me, RC2 did not work even with Flex 6300 configured as a TS-2000. If you search the forum for
"WSJT-X 1.4 and 6000 Control?" you can read our discussion at the time RC2 was released.
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DrTeeth

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Hi David,
*Many* thanks for the heads up on that one. RC3 should be out "soon" so I was told by one of the devs.

Merry Christmas and Happy New Year.
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Larry Loen WO7R

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One of the nice things about the 6300 I own is that it has been the least fussy rig as far as the "JT" modes go. 

Most of the time, I don't even bother with DIGU and run USB because it makes it marginally easier to get that bandwidth high enough.

 Maybe I don't run it enough and should be stricter on my experiments to get better results, but I've been spoiled (lulled to sleep?) about how easy it has been.  I always run with AGC set to fast and then (on WSJT-X) I set the gain to a value usually much lower than I do "by ear".  Basically, when I see the "bar" on the main WSJT display fluctuate a little bit, near the top, it usually decodes pretty optimally for me as far as I can tell.

That said, JT9 is probably a more difficult mode, being darn close to being a carrier, so getting the modulation to "happen" is particularly critical.  I usually run even less power with JT9 on transmit because I find my fans come on quicker with it than anything else I run and even that is well below the usual 1/2 power of standard RTTY.

But, if I'm having problem decoding JT9 signals, I sure don't know about it.
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Ed - NZ1Q

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I use a similar setup as described here. I've run both USB and DIGU with good results. As a matter of fact I'm always decoding both JT modes simultaneously with PSK in another slice via HRD. JT-65 and 9 both decode properly although I've seen on occasion, a JT-9 signal not decode at all. I'll continue to pay attention to when and how that happens, reporting back as I gather data.
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DrTeeth

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I really would like to thank you guys for chiming in with your experiences.

When I first started out, I had the bar at the top as you said Larry, but then I read that the best s/n ratio was for it to be in the middle with the slider close to the mid point. Either way, no JT9 decoded in mixed mode over two solid months' use. I'll test this again as I could have misread the manual.

Talking about the fans, the Flex 6x00 series is rated at full power for 100% duty cycle modes. I usually stick to 30W with JTx modes and rarely the extra fans kick in - surprisingly noisy but not intrusive. Hope they do not kick in much using SSB.
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DrTeeth

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BTW, what rigs are you guys using? Mine is a 6300. That may be relevant. All my settings seem to check out.
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Ed, K0KC

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Guy,

Mine is a 6700, but I cannot imagine that the rig type would make any difference with respect to your problem.

Ed, K0KC
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DrTeeth

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Doesn't the 6700 have more processing power? I'm really clutching at straws now as my settings seem to tally with those people have posted here and with those that one of the devs of the software has advised.

The only variable that I can think of that has not yet been considered is the rig model. I have been virtually full time on WSJT-X since I got my 6300 and can only way I can receive JT9 is as I indicated in my OP, it is a real puzzle.

To rule out the rig type, I wanted to see if somebody with a 6300 can decode both JT65 and JT9, with a 4000Hz Rx bandwidth - I just cannot.

I am open to any suggestions at this point. I have also opened a helpdesk ticket.
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K1UO - Larry

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Being a new (very very new) user of SDJT-X and the new owner of a 6300..I too noticed I cannot use the WSJT-X program set to decode both JT65 and JT9 and have anything decode in JT-9.  No problems with JT65 however.  Have not figured it out here yet either. 

(Edited)
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DrTeeth

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Interesting.

I have just come across some very strong JT9 signals and did some testing.

I can only decode JT9 signals if I select JT9 only mode *and* +2KHz is selected.  No other combination will work. Without the +2KHz shift, even JT9 only mode will not decode if the frequency is not shifted. I'll be QRT (literally and figuratively) for a short while as having some spinal surgery in a couple of days.

Maybe we could get to the bottom of this via email if other 6300 users do not chime in, at least to compare notes and settings. Please use my email addy on QRZ.com.

Merry Christmas and Happy New Year

Cheers

Guy
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Ed, K0KC

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Guy,

Good luck with your surgery...I understand back problems very well, but fortunately I have not had to have surgery (yet).

I hope that you can resolve this problem. As I have said in my previous posts, I have no problems simultaneously decoding JT65 and JT9. I would be really surprised if it turned-out to be a 6300 vs. 6700 issue. Could it be that your computer is under-powered? Have a look (British enough?) at the CPU utilization during the decode to see if it jumps up to something near 100%.

Ed, K0KC
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David--NV0O

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I am using a 6300 on the JT modes and it always decodes both JT65 and JT9 signals, with the divider usually set at 2500. I'm attaching a snapshot of my SSDR settings for WSJT-X below.

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DrTeeth

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Hi David,

Well that is that path blocked.

It's a real puzzle as all other settings in WSJT-X all seem to check out. I may have to wait until SSDR 1.4 and WSJT-X 1.4 RC3 to crack this one.



Snap, hi hi. Please let me know if you can see something amiss.
(Edited)
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DrTeeth

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Ed, thanks for the kind wishes.
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Ed, K0KC

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I do note that you have NB ON, but I cannot imagine that you need to turn it off to decode JT9, but it is worth a try.

Ed, K0KC
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Tim - W4TME, Customer Experience Manager

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Widen your TX filter to 4300 Hz and set the low end to 100 or 50 Hz - there is no appreciable audio lower than 50 Hz.  Match the RX filter to the same settings. Also turn off ALL DSP noise mitigation (NB); you should never use noise mitigation with digital modes.  And SmartSDR v1.4 is not going to be a "silver bullet" fix in this regard.
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Ed - NZ1Q

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To add to my previous comment, I'm finding in my case, as I mentioned, sometimes JT-9 will not decode. I'm focusing on two areas.
-  First is the pre-Amp. It seems if I have it on (+10dB) JT-9 may not decode - I am still trying to confirm this. It could be a case of overloading WSJT-X some how. 
-  Second is that the receive slice bandwidth in my case needs to be extended. That is, receiving at xx.076, I open up the slice BW to at least xx.0815. That is 5.5 KHz wide. This seems to give me the best results with WSJT-X 1.4.

Will post if I find more...

(Edited)
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Ed - NZ1Q

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I've played further with the Pre-Amp settings and the gain does not effect the JT-9 decode as far as I can tell.

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DrTeeth

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Thanks all for your input. It is only recently that I started using NB with digimodes - I could not decode JT9 before I used it but off it will be from now.

I shall widen my filters as suggested, but puzzled how that will let me decode a JT9 signal at 3000Hz, when narrowing them does allow a decode.

I'll try all suggestions of course and will report back - it may be a while.
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Ed - NZ1Q

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Guy, I've been playing with this as I have an intermittent decode problem with JT-9 at times when using the combined decode modes.   I too have proven to myself the bandwidth setting is not the real issue.

However, I've seemed to make some progress on playing with the Rx amplitude slider on the lower left of WSJT-X while also playing with the AGC slider in the slice receiver. I seem to get more consistent JT-9 decodes with the WSJT-X receive amplitude is set around 20 as compared to 30 (the recommended setting).

Ed  -  NZ1Q

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Larry Loen WO7R

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Ed, that's a potential game-changing observation.  Some have trouble, some do not.  It is good to remember how close to a carrier wave JT9 actually is.  Perhaps, despite its design to enable it to function as a weak signal mode, there are critical threshholds in practice where you just get nothing if the signal isn't set properly.  Perhaps we are all missing signals to a greater or lesser degree.  JT65 appears to be much more popular than JT9.  But, some of that may be that we're all losing some of the JT9 signals, some of us more than others.

I wonder if the underlying setup ahead of the radio matters.  For instance, I am blessed with a crank up tower whose height varies from approximately 55 to 65 feet (depending on where I left it) and substantial gain in nearly _any_ direction over many lower mounted antennas simply as a function of height.  That doesn't count the cases where the beam is favorably pointed.  My location is quite rural, so I have a decent setup in terms of local noise as well.  Maybe that explains my relative success where I don't have to care much about the various settings and can decode both JT65 and JT9 without a lot of fuss.

I do play with the ACG slider on the Flex, but I haven't fussed with WSJT-X's amplitude at all.  Maybe I should; perhaps my own results will go from "decoding" to "decoding more".  Currently, I just set it so that I see "some movement" near the top of the vertical bar on the left.  That seems to lead to better decoding.  For me, it appears to be enough.
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DrTeeth

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Initial testing shows nothing else works other than setting +2KHz and reducing Rx BW to 2KHz. I can turn JT9 decoding on and off like a switch with 100% reliability using this method. WSJT-X 1.4 RC3 should be out soon according to one of the devs and from what I read there will be big improvements to the decoding engines. May be best to wait and see what the official RC3 brings?
BTW - I don't know what 'soon' means.
(Edited)
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Tim - W4TME, Customer Experience Manager

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Do you have Flatten option in WSJT-X unchecked?  The DAX audio resonse curve is very flat and flattening a flat signal causes decode problems in WSJT-X
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DrTeeth

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Thanks Tim, will check and try that later.

HNY es mni 73 de Guy
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Greg - K5GJ, Elmer

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Official Response
Hi folks - We've been doing some significant testing here in the shack with WSJT-X and while I don't have the White Paper ready to go, I'd like to throw out a few hints and see if anyone has better luck decoding JT9 in "BOTH" mode:

1. DIGU
2. Set the Slice Passband to 5.1kHz.  This will cause the radio to optimize for digital modes with lower latency.
3. If you set the filter > 5.1kHz, it's not necessary to uncheck the "FLATTEN" in WSJT-X.  You will need to uncheck if you want to run a narrow filter.  Here is a note from "JT" himself regarding FLATTEN:

WA3CAS wrote:
> If you’re a TS-590S owner you may be interested in knowing that when
> I first used the new Flatten option I observed a severe distortion
> of the waterfall. I had the bandwidth was set to 100–4000 Hz, which
> worked perfectly with the old Slope control.

For those who'd like to know what is going on:

The *Slope* control allowed the user to apply a straight-line 
("straight" in dB) adjustment to the passband shape. The correct slope 
had to be determined by trial-and-error.

The *Flatten* algorithm automatically fits and removes a second-order 
polynomial to the lower envelope of the averaged spectrum. The active 
region for this fitting presently extends from 200 Hz above the lowest 
displayed frequency to the highest displayed frequency. If your filter 
cuts off well above 200 Hz, or well below the highest displayed 
frequency, *Flatten* (in its present form) will cause the "distortion" 
you observe.

You have two possible solutions: use wider filter in your receiver, or 
reduce the highest displayed frequency in your waterfall. YOu can do 
this by reducing Bins/Pixel or reducing the width of the Wide Graph.

> At first I thought Flatten was useless, but changed my mind when
> I increased the DSP high cut to 5000 Hz. When I did that, the
> waterfall became perfectly flat (and I do mean flat) with no signs
> of distortion. Wonderful, wonderful, wonderful.
>
> The only problem with using Flatten with the 590S is that I can’t
> narrow up the bandwidth or use the radio's Data filter without
> encountering distortion. If I deselect Flatten, the Waterfall
> baseline drops and disappears. I need to do a considerable amount
> of tweaking of the Zero and Gain controls to produce a useful but
> not ideal Waterfall. Also, by deselecting Flatten there’s no way
> to flatten the response unless I change the 590’s RX audio response.
> For me, deselecting Flatten is NOT an option.
>
> If this were a perfect world, I would have the option of selecting
> either Slope or Flatten. But until then, its 100–5000 Hz forever.

What's the disadvantage in using the wide filter? With my TS-2000, I do 
almost exactly what you are doing. (I use Lo Cut=200, Hi Cut=5000 Hz.) 
Unless you have an extremely strong signal in the 4000-5000 Hz range 
-- enough to cause Rx blocking or undesirable AGC pumping -- WSJT-X will 
just filter that range out, and you'll never know anything was there.

Finally -- it's surely possible to do a better job with the *Flatten* 
algorithm. I just made it work well with my system, with a few 
different test filter widths. If you have a system in which it does not 
seem to work well, send me a *.wav file and your wsjtx.ini file as an 
example. Ideally your example *.wav file should have only a few (or no) 
signals present.

-- 73, Joe, K1JT

4. Set AGC-T to 45-50 and use SLOW.  You can adjust the level if you need to.  I suspect you'll have plenty of excess gain to play with.

5. Use the DAX Control panel RX slider and the WSJT-X slider to set the RX level in WSJT-X to about -30dB with NO SIGNALS present.  The best thing to do is try to catch the quiet period at the end of each minute.  Joe's manual suggests that you try to keep his slider as close to center as possible.  I bumped it down some so I could keep the DAX slider sort of in the middle as well.

6. For JT9 transmit, you'll need to set the TX BANDWIDTH "HIGH CUT" to 4.5kHz or so.  It's a very sharp cutoff above that.


Once we got everything set well, we've had excellent results pulling signals out of the deep noise.   Please try some/all/none of the above and give feedback on what works and doesn't.  

73, Greg - K5GJ
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Ed - NZ1Q

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Hi Greg,

I've been experimenting with settings as well. I've found that my settings are essentially the same as yours other than the bandwidth I set the receive slice to. I use just a bit less - 4500 Hz.  I'll open up my receive a bit more and see how it works.

Looks like you are honing in on how to get the best JT-9 decode when both modes are being used.

Thanks,

Ed  NZ1Q

(Edited)
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Ed, K0KC

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Greg,

In your testing with WSJT-X did you observe the "sidebands" in the Wide Graph that seem to be occurring randomly (although most evident on strong signals) as the result of a DAX issue, which first showed-up in version 1.3.8? The temporary fix is to stop and restart the DAX channel, but this a pain in certain parts of the human anatomy.

If not, perhaps you were testing with version 1.4 and hopefully the problem has been fixed.

Ed, K0KC
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Greg - K5GJ, Elmer

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Ed.... Good point!  I'm not back in the office til 1/5 so I'll see if I can get someone to wander into the shack and see what version of SmartSDR and WSJT-X we were running. 

Regarding the sidebands, I actually haven't seen them but know what you are talking about.  Just make sure you have everything in DAX set to 48000.  You can go to your soundcard settings in Windows and just look to make sure.  That will stop any resampling that might be going on.  
Greg
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Ed, K0KC

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Greg,

I will check the sampling rates, but I am pretty sure everything is 48K. I do not think that the sideband issue is related to mismatched sampling rates as you can make them go away by simply shutting off the DAX channel that you are using for a second or so and then turning it back on. Also, the sidebands seem to come back up on a random basis after making them disappear after the shut-off.

Thanks for having someone take a look at this and enjoy your time off.

I would say "Hook 'em Horns", but it seems like the Horns got hooked themselves...maybe next year will be better.

Ed, K0KC
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Ed, K0KC

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Greg,

According to the WSJT-X manual, the only waterfall control that affects decoding is the "spinner" control that sets the position of the blue line that separates JT65 decoding from JT9 decoding. Assuming that the manual is correct, all of this discussion about "flatten" affects only the waterfall display and cannot be responsible for decoding difficulties with JT9.

Although it is not relevant to the current discussion thread, the manual is not quite correct...JT65 signals can be decoded above the blue line.

Ed, K0KC
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Tim - W4TME, Customer Experience Manager

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Ed - we have conclusive decode data that shows the flatten control is a factor.
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Ed, K0KC

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Hmmm...perhaps the manual has not been updated to reflect the most current state of the software.

Ed, K0KC
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Tim - W4TME, Customer Experience Manager

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Wow!  That really happens? :-P
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George Molnar, KF2T, Elmer

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Thanks, Greg & FRS Lab!

Tried out the settings and concur they work very well. Practically eliminates AGC capture by strong stations, and seems to create a clearer waterfall (on WSJT-X). Not sure the reception is better (haven't gone deep into the numbers), but it seems that it should be. Very surprising - in a good way. Looking forward to the write-up.

I had been using fast AGC with the slider down in the 30's, and a 4 kHz filter. All JT profiles are hereby updated.

Happy New Year & may 2015 be a prosperous and bug-limited year for us all...

Geo
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DrTeeth

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Further to the "flatten" comment by one of the main devs, "Note that the flatten algorithm has no bearing on decoding and only impacts the waterfall display and signal
spectrum power display."
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Bernie

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What version of WSJT-X are you using?

Bernie
W4BGH
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DrTeeth

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FWIW, I also found the JT9+JT65 mode much better than the JT65-only mode for decoding JT65 signals.