Re: Tone or birdie every 500 Hz in USB mode
开云体育
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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