Delay going from keying radio to transmitting data

[dsachnoff]

I am using a Flex 1500 VAC and PSDR 2.8.0.105. The computer is a Dell XPS 8700 with i-7 CPU at 3.6 ghz (8 CPUs). There is 16gb of ram. The OS is WIN 10 Home 64 bit. All the drivers are up to date so based on this info the PC is more than adequate. I have run LatencyMon and it shows the highest measured latency was 888 us and the avg is 136 us. It also says "system appears suitable for handling real-time audio and other tasks without dropout". The audio sample rate is 48000 on the computer, VAC and in the Flex 1500. VAC is v4.15, however, it shows 4.51 in about section of the audio panel.
Right now it looks to be about a 1 sec delay from transmit to power out. I have had to wait as long as 3 seconds from transmit to power out over time. I am not sure what else I can check out.

I received the following from Dudley: "It took several hours, but finally got the added delay. It seems to be in the VAC link in PowerSDR, once it occurs, just toggle the VAC1 button and then the radio will have output at the same time as WSJT -> VAC -> Soundmapper .. I am going to lower the audio buffer size down to see if that will help the issue. Should let Darrin know of this issue.

Dudley"

Any thoughts about this?

Don - kx9q

[ke9ns]

I know certain versions of VAC v4.xx dont work correctly, but I dont know remember which versions, since I no longer use VAC.

I would do this.
Go and download and install the free "voicemeeter Banana" program. It comes with a set of drivers for MME, DirectSound, and WDM-KS
You dont need to ever run "VoiceMeeter Banana", just install it to get the drivers. Sometimes I use VoiceMeeter to do some audio processing on my PC MIC, so you might like it if your using your PC as the MIC for the radio.

I have been using "WDM-KS" for everything now that "Voicemeeter Banana" has fairly good drivers included.
Using WDM-KS allows you to reduce the buffer latency from 120 msec, down to 40 msec on my Flex-5000. (see VAC1 settings).

Now your Flex-1500 uses USB, so I am not sure if you can reduce this latency over the USB port since I am using a 1394 FireWire port?

Its possible that your USB port is causing the lag your seeing? Not sure

in WSJT-X:
File->Settings->Audio->
Input: VoiceMeeter vaio
Output: VoiceMeeter aux vaio

Launch PowerSDR in Administrator mode

PowerSDR VAC1:
Driver: WDM-KS
Input : VoiceMeeter aux vaio
Output: VoiceMeeter vaio
Buffer Latency: 40
Sample rate: 48000

Activate VAC1

Open the Spotter Screen can click on the "Time Sync" to update your PC clock time.


See how that works.


Darrin ke9ns

[hb9bun]

Hello Don (and Darrin - you may remember our mail exchange)
Do you still suffer from this issue or did the installation of VoiceMeeter help?
Sorry for you, but happy for me, I suffer from the same issue since a long time. I also use the workaround to first thing working with the PSDR I close and open VAC. Like that the delay between pushing PTT and the start of the computer audio being sent is set to minimum.
BTW I read about such an issue existing with Flex-5000/PSDR in earlier releases but there it was written, that the issue was fixed at a certain release.
On observation: The delay TX after PTT delay is also increasing a bit every time you transmit. So if you are hitting switching to TX a lot (e.g. last weekend in the FT-8 Contest - or in the old reports in RTTY contests) the TX delay is getting bigger much faster. So this weekend I had to do the VAC off/on every 30 minutes maximum. I only remarked it when strong stations did not answer. VAC off/on and I had an immediate reply.
I also had the impression that after a certain time VAC off/on did not work anymore (twice). I had to restart the PC (at least I did it, maybe restarting just the software would have been enough.
This was the reason for me to dig again into this. I saw this post yesterday and over night I installed VoiceMeeter applying the settings above. My PSDR is not active since about 12 hours and I have the impression (to be confirmed) that the delay is STILL growing. It is not that big yet, but it looks like for me the VoiceMeeter drivers do not make a big difference.
It would be great to know whether it helped you.
73, Peter - HB9BUN
P.S. I run a Flex-5000, with PSDR 2.8.0.108, on a Win7 most recent updates, 16G RAM, i5 processor and 512 G SSD. Flex Driver I have now set very conservatively to 48 kHz Sample rate, 2048 Buffer and Lowest Latency Op Mode.

[hb9bun]

I can now confirm that with above changes delay is still increasing over time.

[ke9ns]

Peter,

Are you saying wjst-x starts to transmit (sending a PTT command) at the proper time, but the radio does not PTT on time, or does the radio PTT properly, but the audio stream is delayed?

if it is the audio stream delay then try this:
If you RIGHT click on the windows tray speaker icon, and select "Sounds"->Recording. Find the device your using to get audio back to PowerSDR. (I use VoiceMeeter Aux VAIO). Look at the vertical bar graph on the right side of the device your using to send audio back to PowerSDR. Does the graph show audio when wsjt-x starts to transmit? Or do you see the delay before the graph reacts?

Try it when everything is working properly, and when you notice the delay.




Darrin ke9ns

[hb9bun]

Darrin,
Yes, wsjt-x sends the PTT command, the radio goes to TX immediately, but the audio stream starts delayed. And the delay is increasing over time, after 6 hours it is around 2 seconds. With putting VAC1 off and on it is reset to a minimum delay.

Now I did test as you suggested, and it is obvious that wsjt-x transmits immediately (VoiceMeeter Aux Input) shows volume, but in PSDR I only see the signal moving up only about half a second later. This now that I had pushed VAC1 off/on a short while ago. I will test after a couple of hours later tonight.

I will send you a little video by email.

73, Peter - HB9BUN

[ke9ns]

If anyone is having an issue where the radio goes into PTT and starts to transmit, but the digital audio stream is lagging (delayed), one possible solution was discovered by Peter HB9BUN. Try using VOX to start the transmit.

One other possibility that has not been tested, would be to try using CAT commands to PTT the radio, instead of the PowerSDR Setup->CAT Control->PTT Control COM port? Not sure about this until it has been proven or dis-proven.

Darrin ke9ns

[hb9bun]

Thanks Darrin for your help. Without using the PTT Control through the COM port, there are no increasing delays. Using PTT via CAT command or VOX works fine. VOX only has the disadvantage that if you do changes to the audio settings, VOX has to be switched ON again. Using digital modes the VOX setting is not visible in PSDR. After one or two times the user knows what the reason is PTT suddenly does not work anymore.
73, Peter - HB9BUN

[ke9ns]

Peter,
Thanks for confirming that using Cat for PTT, or VOX is the solution.
I never use the "PTT CONTROL" COM port, so I never realized it would cause an accumulating TX delay.

As for the VOX, I can try to put the VOX slider on to the Digital panel (just like it appears on the Phone panel) since you can now use VOX over VAC (and a big reason to use VAC is for Digital work)

Darrin ke9ns

[hb9bun]

Hello Darrin
Not that good news. I have been working now quite a while using VOX, it seems to work without issues.
Just out of curiosity and because VOX as described sometimes is switching off in the background (by manipulating with Audio Settings in PSDR), I switched to CAT PTT instead.
And after more than one day of not touching the system, I had a 5 seconds delay between the application going to send and the PTT being switched on. So the only solutions right now is to use VOX to switch PTT when PSDR input audio input signals come through VAC1 (I assume VAC being enabled). A mentioned the audio transmission is starting properly, it is just that there is an evergrowing delay of the PTT TX signal to arrive.
Sorry for the "bad" news, at least I have a solution.
I switched btw my PC to Win10 now.
73, Peter - HB9BUN