Work around for FT8 time sync problem with older Flex units

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Hello if you have operated FT8 mode with your Flex radio and noticed the decoding has decreased or has problems the longer you operate then this might help. If you notice the DT column when this problem occurs the numbers get larger indicating your time sync is not staying in sync anymore. This has been traced to the VAC use and there does not seem to be much in the way of a remedy for this. Some seem to not have problems but many ops do. Here is my solution: use the line out audio on the rear of the Flex radios. There is a DB9 female connector on rear (looks like a serial port but it is not) here pin 9 is line out RX audio this is independent of the volume control but can be adjusted by use of the Flex Wire Out in the mixer screen. Pin 5 is ground and Pin 2 in line in. See attached picture for the DB9 pin out (rear view). I am using this with great success and now no DT problems. Prior to using the rear connector I did use the phone jack on front but this level is affected by the vol control. DT is a function of the time differential between your computer and any received station. And when this gets to be to great the decoding is diminished. Most ops find this increased as time using radio increased restarting PSDR will temporarily fix but using the DB9 is a permanent fix. I did not change my use of the VAC for TX audio I am only using the line out function. I am using a shielded cable with a stereo male 3.5mm (1/8inch) plug to take the RX audio to line in on my radio use sound card. I hope this might help if you experience problems using FT8 with your Flex radio. 
73 Morris WA4MIT
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Morris Wideman

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Posted 10 months ago

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WX7Y

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VAC should work fine
is your computer synced using a known good time sync source?

BktTimeSync by IZ2BKT is a nice little time sync program that may fix your issues, IF you sync the computer every day or so.

Not sure this will help or not but I do know that this is the main reason most of us have had the Issue you described above.

Your mileage may vary of course.

Bret
WX7Y

(Edited)
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Greg - N8GD

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I agree this a computer time synchronization issue. I would, however, recommend using “Meinberg” which is a time service installed on your PC that continually steers the time to correct it using a known standard time source, e.g. NIST or others. Once daily corrections are usually insufficient.
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Morris Wideman

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Hi Fellows
Thanks for your reply`s but this is not caused by the lack of computer time sync, as I stated this involves the RX VAC for some reason it causes a delay which increases over time that you are on the air with it running. People using VAC`s for other non ham uses see problems with delays. Not having your computer time sync`d affects everyone not just Flex users. I exchanged emails with Ken KE9NS he advised a very high end processor with 12 or more threads seemed to work OK but I had another flex user say he had a processor like this and he still had problems. My solution does away with the RX VAC. Newer Flex radios do not have this type problem and apparently not all older flex users do either but if you do have this problem this solution will work.
Thanks 73 Morris WA4MIT 
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K4MT

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I ran a 5000 on FT8 for a long time and never saw that. Might be because I used VB-Cable. I found it worked much better then the others.  VAC caused me some random problems. And VB-Cable is free.
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Morris Wideman

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I tried those also did not help they are still a VAC type of situation. Do not know why some work some do not?. wa4mit
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Morris Wideman

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Follow up to this: I have two sound cards in my PC one for computer sound (add on card) and the built in for ham radio use. After starting to use my Flex 3K again I also started to have trouble with my PC sound it would sound like everything was under water and the sound would slow down. Hint (delayed sound). I eventually replaced the add on sound card but this did not cure the problem. I noticed this would start after using my flex unit and decided this was the VAC`s affecting my PC sound. I removed the VAC`s and started using the line-in on the rear to feed the TX audio into the Flex it took a while to figure out how to setup the flex to get the line to work I ended up in normal USB now no longer using the DigiU mode and it works just fine no VAC in use now and no more PC sound problems. i believe this is all caused by Windows 10 and the updates Microsoft sends out but I am now able to operate the Digital modes without the VAC`s and it is working good.
73 Morris WA4MIT 
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WX7Y

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Have you looked for a new updated drivers for your computer built in sound card from the computer / mother board manufacturer?
Also try a newer or older version of VAC, back in the day when I was using VAC version 4.10 would do what your seeing but 4.09 and 4.12 would work fine if I remember my versions correctly but that's been a few years
73 
Bret
WX7Y

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Dudley - WA5QPZ, Elmer

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Current version of VAC is 4.50 ,  which seems to work fine and compatible with latest Win10 updates..  

Dudley
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Michel VE2XK

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Dudley the most recent update is 4.60 at October 12 2018 . I don't excately understand how Morris have link that . Here I running the Flex 5000A were have not just the DB9 but also dedicated RCA for OUT and INPUT .
(Edited)
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Morris Wideman

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Hello thanks for your reply`s I personally see no reason to go back to using the VAC method as what I have done has corrected the DT and sound problems. I do use a time sync program D4 and did not have any problems with other radios I own and operate on FT8 mode. All these problems were caused by the use of VAC`s so why go back now. Thanks and 73 Morris WA4MIT
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Bruno Beckers

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I had exactly the same FT8 delay problem using VAC 4.15 (From Eugene Muzychenko) on my F3K.
Replacing it with VAC version 4.6 solved the problem (there's a 32 bit and a 64 bit version).
Also, using Windows WDM-KS instead of Windows-Direct Sound or MME shortened the delay further.
FT8 DT on the F3K is 0.2 in average and it stays there. (On my analog FT897d the delay is 0.1 in average.).
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Michel VE2XK

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Hi Bruno,
I'm curiously not able to select any VAC input and output on PSDR by using WDM-KS and VAC 4.60 i have installing here many month ago already . Can you showing me some screenshot please ? Thanks
(Edited)
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Bruno Beckers

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Michel VE2XK

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I'm able to select the driver Windows WDM-KS but can't find Virtual Cable 2 and Virtual Cable 1 on the list on this side .
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Bob G W1GLV

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This problem does not only affect older FRS SDRs. My 6500 has a GPSDO installed, so the frequency is very accurate. The WSJT-X software is not affected by the GPSDO. In order to keep the radio and software in sync you need some software to keep the computer in sync. I found that Meinberg software does this very nicely. Before installing Meinberg, my DT was in the 1.0 to 2.0 time frame, not good.

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Bruno Beckers

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I think we need to keep two issues apart: Computer time sync and Virtual audio cable latency.
Both can produce bad DT figures.
There are a lot of apps capable of keeping the PC time within specs. I for myself use NetTime.
Update interval is short:190 seconds. That's important.



If your PC time is correct and DT is still increasing, I believe it is caused by the VAC software.
I also made a mistake in my previous comment. I had the DT issues with VAC version 4.12 (i said 4.15). I changed to 4.15 (i said 4.6) and problems were gone. So 4.15 should be an OK version.

Michel, please find below a screenshot of my VAC settings. Maybe it will help you find Virtual Cables 1 and 2. Also, I think you need to install VAC as an Administrator.


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Michel VE2XK

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Thank you very much Bruno but for some reason i was not able to select the virtual cable 1 and 2 after i have select the driver «Windows WDM-KS» . They simply don't appear by clicking the arrow . I suspect that this driver is not present on the computer even with VAC 4.6.
But i find another way with the very great help of Darrin KE9NS to be able to eliminating almost completely the DT problem . Note that i use Meinberg since a while and that this problem not coming from PC sync time at all . The other trick consist to use the VOX capability insteat the CAT PTT command were bring that cumulated TX delai timing issue. If some are interesting let me know . My english is not so gud but i think would be able with a few screenshot and explanation to have that done. I'm a happy Flex 5000A RX2 ATU user since 7 years now. Michel VE2XK