Remote audio stuttering/drop out on transmit

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  • Updated 3 years ago
Others notice transmit audio breakup on my signal.  Running Flex 6500 and modest Lenovo 15D laptop with 2 gHz A6 4-core processor and Windows 8.1.   This happens only on remote, either over WiFi or direct wired connection.  This also was occurring with fellow ham running 6700.  My CPU utilization was less than 50%, two pan adapters and moderate waterfall speed.

I solved the problem of audio break up by closing down to one pan adapter, eliminate the waterfall, and most important was to reduce the frame rate.  In one test Ken, W9IE, (running Windows 7) was able to drag the frame rate slider across and when he hit about "12" the audio break up began on his signal.  All of this is with the reported average CPU utilization below 50% as reported by the Task Manager of Windows.  

It seems to be some sort of interference in servicing the SSDR display and at the same time processing the outgoing audio.  There seems to be no problem on receive audio.

Today, I minimized all display activity, set a frame rate of 9, no waterfall, and held the CPU to less than 15% on receive.  During transmit the CPU average of 4 cores was about 30% and no audio dropouts!  I worked some DX on 17, 20 and did some state QSO party action for 3 hours and no trouble running wireless from from living room.  

I am offering this to those who might be frustrated with Remote operation and hearing complaints of bad transmit audio.

-Brian, W9HLQ
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Brian - W9HLQ

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Posted 3 years ago

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Ken W9IE

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I wonder how important the Display Adapter is in the Lap Top as
relates to the REMOTE Operation.
You do not generally get that kind of information when you go out
and buy a laptop,  Unless it is rated for Gaming .
TIM,   Can you give us some input on this..

Ken  W9IE
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Mike W9OJ

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Thanks for that info. I tried transmitting via remote on my living room desktop computer which is on
a wired LAN and it was a distorted choppy mess. Receive is perfect. I'll try some experiments using your suggestions. It's a low end machine with built in graphics. I have a better machine in reserve. I think that will give me the incentive to replace this one.

73 de Mike W9OJ
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Charlie

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Thanks for experimenting and providing this solution.  Worked for me on my Inspiron with 8 gig of ram and Core I3.  I tried all the other suggestions on other threads, but yours worked.  Just got done with a 30 min qso on 20m and had no distortion, clipping, or drop outs.  Again, thanks for your solution.  73 de KJ4AUQ
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Burch - K4QXX

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I have also noticed that making the SSDR window small (instead of full screen) helps on my laptop.  I also close the DAX program from the systray and disabled all the unused DAX channels (2-8 in my case) in the audio section of the windows control panel.  In doing this, that stopped 90% of my audio drops.  I am going to try your suggestion of lowering the frame rate and stopping the waterfall.  Maybe that will cure my other 10% of drops.

Burch
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Bill -VA3WTB

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If you think about, the remote computer needs to be almost as fast as the main computer. It is running the same software.
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Tim - W4TME, Customer Experience Manager

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This is correct.  And if you are operating remote, the PC will need to be able to handle real-time audio processing, so DPC issues can be significant.
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William Hemmingsen

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Tim I agree with this statement except, its actually the opposite in my experience.  The remote client needs to be MORE powerful. 

On one laptop I start getting choppy TX when the CPU gets near 50%.  When I key the radio the CPU spikes to near 100%.  Why does TX audio need so many resources?

William
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Burch - K4QXX

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My remote computer runs SSDR perfectly when its being used in local mode.  It's only when it's used in "remote" mode that I have issues.  The receive works perfect in remote mode, even with 4 receivers and 4 panadaters open.  I only have an issue with transmit in remote mode.
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William Hemmingsen

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I agree this is an issue that needs addressed officially by Flex.  TX audio should not need this many resources.  Also audio should be priority over the display.  My i5 laptop will not even TX cleanly with remote audio when connected directly to the switch with cat5.

William
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Dudley - WA5QPZ

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Tim has a point,  with remote you are now streaming audio,  DPCs are important,  particularly on laptops with built in graphic and power settings allowing the processors to slow..  50% CPU rate is ok for Word but may not allow the computer resources to service all the pieces to make streaming audio very good..   Of course your wireless has to be able to pass the streams without breakup..   But there are a couple of things you can do to help your laptops to pass streaming successfully.  

Set Windows Power settings to High Performance..   

https://helpdesk.flexradio.com/hc/en-us/articles/202118748-Optimal-Win7-High-Performance-Power-Optio...

Check that your Graphics is running best performance, or max GPU acceleration

Check your computer for DPC latency,  There is a handle tool by Resplendence that you can run that will help tell you what program or driver is creating the most DPCs..   LatencyMon  (http://www.resplendence.com/download/LatencyMon.exe)     as per this Helpdesk article   https://helpdesk.flexradio.com/hc/en-us/articles/202118698-Using-LatencyMon-to-collect-DPC-Latency-D....

Of course closing down waterfalls, and slowing down FPS  (Frames Per Second)  in the Display pull out will give you more reserve or graphics headroom.. 

Wish there was a magic bullet,  but these are individual things that you have to look for in your system which now is radio, computer and network..    







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Burch - K4QXX

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I turned down the FPS on the panadapter and turned off the waterfall.  That seemed to cut down my CPU on transmit by 10%.  Was able to work Israel, Barbados and Crete last night on 20 meters from my kitchen table running 100 watts remotely (I'm in Florida).  There are a few more tweaks I intend to do but my 5 year old laptop seems to be running pretty good now.  The few times I get a transmit stutter is when some background process (system, windows processes, etc) start using up processor.  Not sure what I can do about that but unless that happens during transmit, it doesn't seem to affect receive.  In fact, receive is pretty much perfect on my laptop, even running multiple panadapters and receivers.  I even made a PSK contact remotely last night.
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William Hemmingsen

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I bought a new I7 laptop and all my audio problems are solved.  I guess the client is not as thin as I thought.  But all is well now!  Made a several DX on the couch over wifi without issue.

William
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Ross - K9COX

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Skype continues to work well for me, quality is great and uses very little resources.
(Edited)
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Brian - W9HLQ

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Follow up on my initial concern:
Here is some follow up information on my findings after spending several hours warming up my dummy load antenna.  I agree this audio dropouts are related to DPC latency times.  If I see the DPC below 600 us, the transmit audio seems OK.  However I could not get a direct correspondence between the FPS setting for the display and the DPC times as reported by the LatencyMonitor mentioned by Dudley, above.  The DPC values may give you an idea of what is going on but nothing firm or definitive from my tests.  The readout value bounces around to much to be sure. 

I got very good performance with one pan adapter and frame rate set to 10 and often much higher.  The water fall had no effect since it does not process during transmit. With this conservative configuration, the Remote operation is solid and works quite well.   I am impressed with the performance.. In all cases network status was excellent and latency <2 ms.  Adding pan adapters only made things worse if their frame rate was moved to faster rates.

My one year old Lenovo IdeaPad Flex 15D supporting my Flex 6500 has the following hardware:
AMD A6 processor running at 2 ghz (four cores)
5200 APU Radeon HD graphics (I believe the graphics is part of the mother board)
4 gb RAM
Windows 8.1

I would consider the above equivalent the minimum system to expect to run Remote.  As mentioned above, as we do more  sophisticated activities with our system, the idea of a simple thin client for SSDR is not true. We don't need a gaming capability computer, but maybe the next step below?   

I accept the above performance with this very cool Flex Radio system knowing the limitations of my laptop.  I hope others do not despair in their efforts to run Remote until they evaluate the "horsepower" of their computer.  I will change my entry here from a "Problem" to "Suggestion" and request Flex documentation to include hints on approximate sizing of the client computer.

I don't understand why the resource needs differ when using Remote transmit.  I should think the audio needs are the same for receive processing or transmit processing.  Perhaps someone can explain this to me.

Thanks to everyone who took the time to comment on this issue.  Brian, W9HLQ