DAX Sputtering/Popping on TX

Sparks

Hi guys- Using Channel 1 DAX on 1.2.1 with Windows 7/64bit, The RX is ok, but the TX is popping and sputtering - causing corruption of the data out. It does it even at one watt into a dummy load. Windows 8 on the Dell tower works OK, but the Win 7 Lenovo I5 laptop (ham PC) is doing this. It sounds just like when you used to wiggle an intermittent analog audio cord. Tried making DAX real-time priority.. turning off all other DAX channels..no help. I'm a digital-only ham..help! 

Mike NN9DD

A while back I experienced something similar. I shut down Dax and restarted it and that seemed to help. Also, does it so it on channel 2 as well Mike N9DFD

Sparks

Yeah, sometimes re-starting it helps...but then it falls apart again. Actually, it won't go to channel 2.
I set everything correctly and it is dead. No audio either direction. I think it is a latency thing..the digital audio flow isn't consistent and it drops momentarily. What's bizarre is that the RX Ch 1 pathway is fine. It's only on TX. Luckily, I can use my tower Dell PC..which seems fine. I hope the Flex guys have seen this!!  Bob-AB5N

Mike NN9DD

There is a thread out here somewhere that talks qbout going into the propoerties in the audio device and setting the rate to I think 48000 to eliminare any windows errors. I could mot find it quickly but its out here

Mike
N9DFD

Sparks

Golly, I wish that was it...seems like it now defaults to the correct 48khz setting. Got ch 2 working..slightly better, but still unusable.  Thanks though!

Mike NN9DD

One last thought and I'm sure you done this. I brimg it up because I have done it and It threw me for a minute. You have 5he Dax button on the transmit panel on and it is in DIGU. I am sure you dome this but just in case Mike

Robert -- N5IKD

Are you wired to the network, or using Wi-Fi?

Sparks

The 6300 is direct RJ45 into the Lenovo Laptop. The laptop now uses WiFi for it's net connection.
Should I hardware everybody to the router? The Dell I7 tower works fine with the exact same setup...RJ45 to it from the 6300 and WiFi from it to the net. If the DAX wasn't getting enough machine cycles to make it real-time, the RX should be affected too, but it isn't! I tried upping the buffers on the ethernet port..128 TX 512 RX (PC hardware settings). No help.
This is very strange indeed. Took me a month to get my 3000 working...thought this one would be quicker...

Tim - W4TME

I suspect that the laptop is experiencing some long duration DPCs that is interrupting the audio stream on the laptop.  Disable the w-fi and if the performance improves, DPCs are most likely the culprit.  

Sparks

I took a good look today using a Latency monitor. I disabled everything that wasn't necessary. Before, I was getting a few hits above 2000us...but after, was able to get the PC to stay under 500us for long periods. There was little correlation with the sputtering. I was running 1 watt into a dummy load. If DAX audio IN is selected, Tune keying the radio will produce the effect...the third party program need not be on.  Sometimes it starts out clean for 15 seconds..then it goes bad...then cleans up for a period. Wide DPC's do effect it, but it seems that even 500us DPC's are too much for it. This is a common-combination Lenovo I5 / Win7 laptop. It was running a 3000. This is going to show up a lot. I'll keep hacking at it!

Tim - W4TME

This type of problem is a challenge.  DAX is performing real-time audio processing on the PC and as you have seen, the performance level is dependent on PC hardware, but not necessarily directly related to a particular hardware spec.  We this this a lot with PowerSDR where it too is a real-time audio processing application.  Some laptops just don't perform well.  Most of the time we can identify a DPC problem, but if you are running with no spikes above 1000 uS, then DPCs are probably not the culprit.  Good luck in your hunting.  Let us know if you fine a silver bullet fix.

Reg

Bob:

There are many things that can cause DPC latency.  This is a fundamental problem for manufacturers and distributors of audio/video equipment and software.  Some of the retail distributors have invested considerable effort into documenting methods to diagnose and fix DPC latency problems.  The best support site I have found is on the website of a musical instrument and pro audio retailer named Sweetwater.  I use their optimization procedures on all computers that I use for audio/video editing or amateur radio.

This first link is titled "Solving DPC Latency Issues:"  The link combines an excellent explanation with links to free tools.

http://www.sweetwater.com/sweetcare/articles/solving-dpc-latency-issues/

This second link is to detailed written instructions for optimizing the performance of PC and Mac computers.  There are separate instructions for OSX 10.5 through 10.9 and Windows XP through 8.

http://www.sweetwater.com/sweetcare/mac-pc-optimization/

My bet is that if you work through the Sweetwater instructions your PC will perform better.  Unfortunately, there is a problem with ACPI.sys that applies to a few laptops that cannot be fixed.

Good luck and let us know when your "pops" go away.

Reg (FLEX-6700 Owner) 

Sparks

OK...I'm pretty much home safe. Here is the Final Info for Laptop users:

Because of power management and other housekeeping utilities common to Laptops, it
is really hard to create a real-time un-interrupted flow of data such as DAX requires. It is not related to the abject duration of DPC calls, but more the occasional big hit of over 2000us. The above links will walk you through turning off almost everything that causes these DPC hits. WiFi is the most common problem, but in my case it was a combination of smaller services which made my TX DAX channel unstable. Use the utility above. I also found another free DPC monitor utility also helpful: dpclat.exe  . Remember that once you see that there are no big DPC hits (and your DAX is clean), you can start to turn back on services and start-up items that are most helpful to everyday operation, as long as they were not the main offenders. Conclusion: Laptops are not well-suited for SDR operation. A small dedicated PC tower with nothing else on it- would be ideal. Best of luck to everyone out there!

Al K0VM

From a different angle... How much does the time on the PC drift?  I HAD one PC where (un-corrected) the PC clock time drifted several minutes per day.  I was never able to make VAC work for more than a few tens of minutes at a time.  I don't use that PC for SSDR/DAX so don't know if DAX would have the same problem.   The problem appeared to be that one end of the VAC connection was using PC sample rate reference. the other end was using F5K sample rate reference.

Syncing the PC time to  internet time did not change the PC sample rate.

Just a thought.

AL, K0VM