Dirty distorted transmit signal

Phil M0VSE · September 2015

Yes I have the flex set to 1-2% power and the audio is coming out of an Icom IC-7100 with no antenna connected.

Phil

Ed.G · September 2015

Thanks Phil

Cal N3CAL · September 2015

Well I guess it sucks to be me "one of a hand full". I suppose you guys would like to see us just go away? 73

Cal/N3CAL

Rick WN2C · September 2015

I had the same looking display on transmit. It kinda looked like multiple signal or copies of the transmit signal on either side of my transmit frequency. I got on the air and asked during a QSO if my audio was distorted or if there were any signal / audio artifacts on either side and was told no my signal was clean. How many of those affected by the bad signal on the display have actually been told that there signal or audio was distorted?? I shut the radio and computer off at the end of the night and rebooted the next day and it was fine, albeit the signal on the display was showing wide on transmit but no distortion showing in the signal displayed. (No extra spikes in the displayed signal like W8TZ Ross showed) Running 1.5 / 6300

rich · September 2015

One of the difficulties in identifying the problem and coming up with a solution is that, at least from my perspective and what I run (JT modes almost exclusively on a 6300 with Win7) is that the distorted audio doesn't show up right away. Most of my distorted transmit troubles start hours, sometimes many hours (>10) after startup. How many testers are going to sit and run JT mode for several hours?

Here is a clean JT65 signal (Yes, I do run SSB mode and have so for the last 18 months with no compression and no equalizer - that's not pertinent).

Here's a distorted signal taken after 4 hours of operation:

If I continue to operate, then the distortion worsens. Other stations will often comment. So when it occurs, I QRT and reboot the 6300. When I restart SSDR all is fine.

Because of the paucity of reports, i.e. "... only a handful of people are reporting difficulties ..." I send this along. 73, Rich, K3VAT

Jim Best · September 2015

Looks exactly like my transmit signal but not all the time. Every now and then it becomes a clean signal with no action from me. Jim WU7G

Bruce - NØJX · September 2015

You can include me with the group experiencing distorted transmitted signal. I also have a 6300 and noticed this problem this evening with sideband. I'm using SmartSDR ver 1.5. I did not notice this problem last weekend.

Bruce - N0JX

Simon Lewis · September 2015

if it was running power behind it yes .. but the demo was only running a few watts ... the audio sounds like that heard from poor bandwidth on a skype connection ... very digital and pulsed mod .. I doubt its RF or grounding ... and root cause would suggest its 1.5 related ... as 1.4 does not have the problem .. if it was RF or grounding I would think that it would be present in any version ...

Steve-N5AC · September 2015

As of today, we still have been unable to duplicate the problem in the lab so we're going to fly in a radio with the issue tomorrow. Generally, if we can duplicate the issue we can get to the root of it quickly. I'll update everyone when we have more info.

Jay -- N0FB · September 2015

Let me know if I can be of any assistance with my 6300.

Ross W8TZ · September 2015

My 6300 has never been back to the factory. I bought it at Dayton May 17, 2014 so I assume it is one of the first production runs of the radio. I did add the ATU last December but doubt that has anything to do with it. It has worked great with all previous versions of SmartSDR and there have been no changes in my shack to radio connections, antennas, grounds etc.

Tim - W4TME · September 2015

Jay - please open up a HelpDesk support ticket on the distorted audio issue. Thanks.

Cal N3CAL · September 2015

FYI, The above dirty signal can be reproduced while transmitting 1 watt into a 50 ohm dummy load. (WSJT-X CW ID via DAX cha 1)

Cal/N3CAL

Howard Koenig · October 2015

same problem here. 6300 windows 7. never listen to my audio but did tonight. I wondered why I wasnt making many digital contacts. doesnt matter which mode or program I use. distorted transmit audio no matter what.

PAØGDW · October 2015

It looks to me that ,, Only a handful of people are having problems '' see post Bill Buchanan...is growing every day..

Tim - W4TME · October 2015

This is the #1 issue engineering is working on. We hope to have a resolution soon.

Jay -- N0FB · October 2015

I will do this morning. I was out of town on business for a few days.

Tim - W4TME · October 2015

Thanks Jay. I'll be watching for your ticket to hit the queue.

Ken - NM9P · October 2015

Good luck to you all. I hope the engineering team has some hair left after tearing it all out with this one! I am sure it has to be exceptionally frustrating. But they are a great team and I am confident that they will conquer this one eventually.

Jay -- N0FB · October 2015

Ticket: 10794 Distorted Audio Since SSDR 1.5 Released

Gary, KE8O · October 2015

I've experienced this problem twice since upgrading to SmartSDR V1.5.0. I don't know if this will help find the problem, but I tend to leave my radio on for long periods of time. I might turn it on Monday morning, and leave it up and running copying WSJT signals for days. This morning my radio had been on for days when I attempted to make a LSB transmission on 75m. When I first keyed up I noticed what looked like several harmonics of my TX signal above and below the original signal on the on panadapter. I stopped SmartSDR and power cycled my 6300 (including removing power) and the problem went away. I believe my 6300 is probably from the first production run as I picked it up at Dayton in 2014.

Tim - W4TME · October 2015

Gary - thanks for your info. We will add it to our list.

David - N5DTX · October 2015

I do not believe the issue is specifically limited to the 6300. I have a 6700 that was upgraded to SmartSDR 1.5 over the weekend. I experienced the same transmit issues on multiple bands in USB, LSB, and DIGU. I have been able to temporarily remedy the problem from time to time by rebooting the radio and the computer. I really thought it was operator error until I found this thread.

I never had the transmit problems prior to version 1.5. At times the problem will begin within the hour of startup, and other times the problem may not show up for hours. I know the FlexRadio team is working on the situation; I just wanted to point out that my 6700 has the same issues with SDR 1.5.

Abed - AB5ED · October 2015

David, thanks for the report. If you're able to, we'd like to see a screenshot of of the issue in TUNE with both SSB and CW.

David - N5DTX · October 2015

Sure, that's no problem. The bulk of my discovery issues occurred during Saturday and Sunday. Since late Sunday night I had been running WSPR on multiple bands, and it was working perfectly until last night. I noticed the wide, corrupt transmit signal again and subsequently shut everything down and rebooted. The radio has been running WSPR just fine since last night and I am still monitoring the transmit signal.

I will take some screen shots when the issue begins again.

Steve-N5AC · October 2015

We have now located the root cause of the issue that a handful of FLEX-6300 customers are experiencing with the distortion in transmit signals. After finding a presumed cause, we tested sample software with five customers in the field and all reported that the issue was cured for them. The change that we made in this test software detected and corrected the issue as it happened, which is not the ultimate correction, but was a conclusive test that we had found the problem. We expect to have the ultimate correction within the next week which will not test and fix the issue, but will instead correct the source of the issue before it ever materializes.

The root cause is rather technical in nature, but I will provide it for those that are curious. There are a lot of high-speed serial and parallel connections inside the FLEX-6000 radios. All of these interfaces require precise timing and clocking to work correctly. Due to changes made over time (new features such as the WNB), the timing of one of these interfaces, the Ethernet connection between the FPGA and the main processor, had changed inside the FPGA resulting in very infrequent mis-alignment of data. Once the data was mis-aligned, data alignment would not recover. For those familiar with FPGAs, the resulting fix is a different kind of constraint, a kind of technical directive to the FPGA tools, placed on the interface that will force the proper timings in the interface. The interface did have constraints on it before, but not sufficient ones to prevent this issue.

Our expectation is that this change will fix this issue on the FLEX-6300 as well as prevent this issue from occurring on any of the FLEX-6000 radios in the future. We're now working hard to prepare an updated software release to all customers containing this important fix and will let everyone know when it has been completed and tested. I appreciate the five customers who worked with us to help locate and fix the issue since we were unable to duplicate this in the lab.

Ken - NM9P · October 2015

Excellent! Thanks and congratulations to all those involved.
And thanks for the technical explanation. As one of the "curious" I appreciate it, even if it is a little over my head. You "dumbed it down" just enough to make me feel that I sort-of understand it! <grin>

Sergey R5AU · October 2015

Great Steve! In case multi CPU timing configuration deployd finally this is will solve many other issues in background ! Congratulation , looking for release !