Receiver filters changing shape.

  • 1
  • Problem
  • Updated 2 years ago
  • Acknowledged
Operating the during CQWPXRTTY contest this weekend on two occasions when changing bands (20 meters to 15 meters each time) the receiver filter shape changed from a "Brick Wall" shape to a very wide and slow roll on and off shape (looking at the shape on the MMTTY and 2Tone signal displays). The only "fix" was to shut down the radio and restart. Selecting different filters, bands, modes, etc. had no effect on the shape after it changed. So I did the Quick Fix shutdown and got back into the contest. The two occasions were about 6 or 7 hours apart. Using a 6700 with the latest Beta software on a WIN 10 I7 desktop computer.
Al, N4AB
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Al

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Posted 2 years ago

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Tim - W4TME, Customer Experience Manager

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Did you check to see what the filter sharpness setting was after changing bands?  Was it at the correct setting for sharpness and that was not what it was set to previously or was the slider indicator not synced with the filter skirt?

And what version of SmartSDR are you running?
(Edited)
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Al

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Hi Tim.

Yes, that was one of the things I looked at the first time it happened. I had set all three modes to “Sharp Filters”, and they were still set to max when I looked. I have attached 4 screen shots of part of the display of N1MM+. Shot 1 shows the RTTY filters at 300 Hz with the Sharp Filter setting on the slider. Shot 2 is shows the RTTY filter still at 300 Hz but with “Low Latency” set on the slider. Shot 3 is done using a 4 KHz USB filter also set to “Sharp Filter”. Shot 4 is a photo shopped picture of what I can remember the display looked like when the Filter changed shape, it was a very wide spectrum that had a peak in the center with straight (more or less) slopes (both sides of center), but not rounded like the Low Latency setting.

As I said in my post, nothing I did seemed to change the spectrum and nothing seemed to be miss-set. I loaded my 20 meter RTTY Profile and the Filter shape was still the same as seen on 15 meters when the problem happened.  I then reloaded the 15 meter Profile with no change seen. That is when I powered down the radio, N1MM+ and computer, took a short break, (4 or 5 minutes) and then turned the radio back on. And restarted N1MM+. When the N1MM+ displays loaded, everything was back to normal. I loaded the 20 meter Profile with no problem and then went back to the 15 meter Profile everything worked fine. So, I went back to the contest. I operated on 15 for a while then went back to 20 without any problem. However, when I again changed to 15 the problem came back. Since my earlier experience at trouble shooting the problem showed no solid results, I just powered down the radio, waited a few minutes and restarted the radio. The computer and N1MM+ were still running and when the radio came to life the filter shapes were again “OK”.

As close as I can remember that is the sequence of events. I’m not sure of what you meant by “was the slider indicator not synced with the filter skirt”.

I am running Beta Version 1.10.15.43

Thanks, for the help.

Al, N4AB.


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Al

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Can't seem to get the photo sequence right when I upload so the top photo is shot 1, photo 2 is shot 4, photo 3 is shot 2 and photo 4 is screen shot 3.
Sorry for the confusion.
Al, N4AB.
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Tim - W4TME, Customer Experience Manager

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Al, thanks for the feedback.  I have entered this problem report into our bug tracker as issue #4487 for additional investigation. Thank you for the defect report.
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Al

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Hi Tim.

The RTTY Filter Shape Change Problem happened to me again on Friday just as I was getting ready for the ARRL DX CW Contest. This time I did try to document it a little better so I have attached the five screen shots that I took.

1.       Shot of the RTTY filter screwed up at 300 Hz.

2.       Shot of the filter after I powered down and powered up the radio.

3.       Shot of the RTTY filter spectrum on DAX 1, screwed up.

4.       Shot of the Radio off Noise Floor.

5.       Shot of the filter spectrum after the power down/up cycle.

Before I turned off the radio (6700 running the latest Beta version software) I tried several RTTY Filter Bandwidths, changed modes to USB, LSB, CW, and back to RTTY. All the mode filters were very dirty and the skirts on the CW and SSB filters were not Brick wall shaped. Everything looked like the RTTY shaped skirts. All the RTTY Bandwidth filters looked the same as the 300 Hz, just the wide hump got even wider.

The only thing I did was cycle the power to “cure” the problem.

Thanks for entering the problem report (4487). I hope it is a software problem and not specific to my radio.

Al, N4AB.

 

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Tim - W4TME, Customer Experience Manager

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Thanks for the additional info.  I have added it to the problem report.