Tone or birdie every 500 Hz in USB mode
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I can also confirm that the CW sounding noise was from the GPS, however after removing the GPS, there is still a high pitched tone on 12m and 6 meters that wasn't there before. I think it's on all bands above 17 meters, but the noise is higher on 17 meters and 10 meters, even with the dummy load, so it's hard to hear the tone on those bands.
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73, Dan - W2DLC |
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My guess is that DIGI mode has a wider bandwidth so more noise. This will cause AGC to cut the gain a little bit and the spurs will appear reduced.
Tony
AD0VC
From: [email protected] <[email protected]> on behalf of Erik Larson via groups.io <kd7ykq@...>
Sent: Wednesday, April 2, 2025 11:27 AM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] Tone or birdie every 500 Hz in USB mode ?
For some reason I cannot get audacity to record from the QMX.. But WSJT-X sees it fine (yes, I closed WSJT-X first before trying Audacity). So no audio recordings but another picture. Mel, mine sounds very similar to yours.
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I have confirmed that the pulsating tone noise at 1Khz was from the GPS module, as with it removed the noise at 1Khz is markedly reduced. I will run it this way in the morning and see if it is better able to decode MSK144 without that persistent pulsating
noise at 1KHz. I still see less of these noise lines in DIGI mode than in either USB or LSB, so I think there is something different with the RX audio? in DIGI that might help with USB also if I can figure out what the difference is.
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For some reason I cannot get audacity to record from the QMX.. But WSJT-X sees it fine (yes, I closed WSJT-X first before trying Audacity). So no audio recordings but another picture. Mel, mine sounds very similar to yours.
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I have confirmed that the pulsating tone noise at 1Khz was from the GPS module, as with it removed the noise at 1Khz is markedly reduced. I will run it this way in the morning and see if it is better able to decode MSK144 without that persistent pulsating noise at 1KHz. I still see less of these noise lines in DIGI mode than in either USB or LSB, so I think there is something different with the RX audio? in DIGI that might help with USB also if I can figure out what the difference is.
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Mel,
Yours sounds a lot worse than mine does! You can definitely hear a solid tone, though, with or without the GPS. With the GPS there is the on-off code like tone under the other solid tone. My QMX high band does not have either of these tones, but my QMX+ seemed to begin having them after I installed the SSB Beta firmware and started experimenting with the band edges over the course of a couple of hours. I think something in the audio line became more sensitive to interference somehow.?
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73, Dan - W2DLC |
开云体育
If I disconnect the antenna, the birdies appear in the FT8 waterfall. When I connect the antenna, they disappear, presumably because the atmospheric noise swamps them. Maybe the AGC is a factor as well. I have a 1 meter loop and an active whip. The loop has
much lower output on 10 meters. On 10 meters I see birdies with the loop but not with the whip. I am talking about the 500hz spaced birdies on FT8.
I find it interesting also that Hans mentioned 500hz birdies coming from the ADC built into the microprocessor. They affected his microphone for SSB. I can't make a connection between that and the RX birdies but it keeps rolling around in the back of my mind.
Tony
AD0VC
From:[email protected] <[email protected]> on behalf of Erik Larson via groups.io <kd7ykq@...>
Sent:?Tuesday, April 1, 2025 1:54 PM To:[email protected] <[email protected]> Subject:?Re: [QRPLabs] Tone or birdie every 500 Hz in USB mode ?
I think it can be corrected with filters or settings somehow. When I change to DIGI mode on the QMX, a lot of these noises disappear. In the image below, the bottom portion was DIGI, the top portion USB on the QMX+ (Pressed the Mode button just as green
line appeared to change to USB RX)
Whatever filtering or settings are different between USB and DIGI, the RX looks a LOT better in DIGI. Notice the lines at 750, 1250, 1750, 2250, 2750 are non-existent in DIGI. The lines at 500,1000,1500,2000,2500,3000 appear unchanged by this, but there
is definately something different between RX in DIGI and USB.
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In this picture, I cycle back through USB to LSB. The bottom half is USB, the top is LSB.
Notice that when I switch between USB and LSB the tone or noise at 1500 and 3k both become more pronounced (stronger signal indicated by line turning red instead of yellow) Also the lines at 500 and 250 get stronger (solid yellow instead of broken yellow).
Earlier today the LSB side was showing a pulsing tone at 750 almost like carrier from CW, but not in any CW pattern.. I did not get a screen shot of that while it was happening, but I now suspect it may have been an external signal. Note that all these signals
I am highlighting are with the radio connected to a dummy load with a 36" piece of RG-8x
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I think it can be corrected with filters or settings somehow. When I change to DIGI mode on the QMX, a lot of these noises disappear. In the image below, the bottom portion was DIGI, the top portion USB on the QMX+ (Pressed the Mode button just as green line appeared to change to USB RX)
Whatever filtering or settings are different between USB and DIGI, the RX looks a LOT better in DIGI. Notice the lines at 750, 1250, 1750, 2250, 2750 are non-existent in DIGI. The lines at 500,1000,1500,2000,2500,3000 appear unchanged by this, but there is definately something different between RX in DIGI and USB.
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In this picture, I cycle back through USB to LSB. The bottom half is USB, the top is LSB.
Notice that when I switch between USB and LSB the tone or noise at 1500 and 3k both become more pronounced (stronger signal indicated by line turning red instead of yellow) Also the lines at 500 and 250 get stronger (solid yellow instead of broken yellow). Earlier today the LSB side was showing a pulsing tone at 750 almost like carrier from CW, but not in any CW pattern.. I did not get a screen shot of that while it was happening, but I now suspect it may have been an external signal. Note that all these signals I am highlighting are with the radio connected to a dummy load with a 36" piece of RG-8x
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Stan,? Yes, I'm sure about that. After I read reports of that I checked for tones and birdies. I found a few birdies here and there, but not these tones. They also were not there at first with the SSB software, but appeared after I started experimenting with band settings and calibration. I noticed the case got very warm after about 2 hours of trying different configurations, and then at one point I got a high pitched, very loud screech on one band. I noticed these in and off beeping noises after that, and it seemed like the birdies became more noticeable too. Something changed.?
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73, Dan - W2DLC |
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On Mon, Mar 31, 2025 at 02:41 PM, Daniel Conklin wrote:
I didn't notice it in digi mode before the SSB beta.
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73, Dan - W2DLC |
Daniel Conklin