spikes in transmit waterfall with FT8

jim

Mark_WS7M

Mike - K6QY

This apparently arises when there is computer latency exceeding a couple milliseconds. You can check your latency using the app LatencyMon. To minimize this, I was able to adjust the number of cores and RAM allocated to Win10, as I am running VMware Fusion on a Mac Pro. I’m not sure how you’d fix this on a native Windows machine... reduce simultaneous processes and increase RAM?

jim

Mike - K6QY

Yes; this is from computer latency.

RoyS

Mike - K6QY

While I won’t discount that possibility summarily, the intermittent and precipitous nature of these glitches is more consistent with latency issues. In my case, it wasn’t related to audio drive levels at all. Bur it definitely should be ruled out as a potential cause.

jim

ROY 
i have tried   but it  is still the same 

jim

Mike 
i am working  on  latency    
anything  special  i should  look for  that may help 

thanks 

Dudley WA5QPZ

jim

thanks  Dudley,
i will  start  looking     

TU 

Conny

Conny

I should add that SDR was not running on the PC.
Only CAT was running on the PC connected to the 6600M

bahillen

I have worked with Tim on this exact problem last year with a help fest ticket for 6 weeks, step by step. All computer drivers need to be updated. Check Task Manager for any 100% CPU usage. 16 GB of RAM needed to reduce memory swapping Need separate video card, not on board video Turn off Spots especially if a lot of spots Minimize any apps that are not being use Chrome can eat up a lot of CPU and interrupts Shut down apps you don’t need at the time. Install LatencyMon Track what helps and what hurts. Eventually you can improve you computer performance. You may get to a point where you can use Spots etc. After you are not analyzing close Task Manager and LatencyMon because they can use CPU resources. Just when FT8 is crunching decodes other processes that use the bandwidth and causes an interrupt generates a transmitted blip. I was surprised that so many applications drivers have problems. Video drivers seem to be problematic. LatencyMon will identify which drivers may be causing a specific interrupt. I still get an occasional blip but have reduced it to a point where it doesn’t affect operating FT8. I have a Flex 6600, run multiflex, WSJT-X , Windows 10, I7-7700, SSD and run 4 instances of WSJT-X with JTAlert. I learned a lot about my system while working through this issue. 73 Bill W9JJB

Conny

Mike - K6QY

bill - tnx. you summarize it well.

jim

jim

Conny

bahillen

Something I observed in the past with my problem. The pops were obvious during TX but on RX , as I recall, there were pops but were hidden by the audio. Also in FT8 key up there is a pop in tx audio. Some times I saw a consistent pop/spike 4 seconds into 15 second FT8 TX. Hope some one can figure this out. 73 Bill W9JJB

Val DM1TX

bahillen

Conny This is an important observation it seems. If any command interrupts DAX audio that explains a lot. The command length may take too long for Windows to process and causes an interrupt. Normally an interrupt of 250 micro seconds can be handled but the interrupt quickly jumps to 1,300 micro seconds as operating system tries to handle the issue. This is as viewed in LatencyMon. I am not a Driver or OS person but have run and watched the test a lot. Seems like some investigation would be of benefit by the Flex Technical staff. As I have learned working with this in the past, Windows operating system is not a great performer for audio processing of real-time audio because of the interrupt handling structure. That is not to say other common OSs would be better. I also run my 6600 24/7 and have to stop and restart the TX button every 2-5 days or it sends our a 3kc band of audio and can be heard in the TX Monitor audio. This is a known DAX Driver bug. Unrelated to the subject here. 73 Bill W9JJB