开云体育

Hi! Has anyone here ever looked into the issue of inherent audio noise in the RX audio path of the Xiegu X6100? Lately, I’ve been listening to this device a lot on headphones, and I have to admit that, for example, compared to another QRP device I have on the bench — a transceiver based on Chris M0NKA's project — the Xiegu fares very poorly (the situation is similar when comparing the X6100 to the Elecraft KX3 — but of course, the KX3 is in a somewhat different league, so I’ll leave that comparison aside).

I don't have any solid measurements to share right now, but simply plugging headphones into both transceivers with the VOL/AF Gain turned all the way down reveals huge differences! I say this with a heavy heart, but the X6100 sounds like a terrible noise box!
When working with an external speaker, it’s not as noticeable, but with headphones, it's quite pronounced.

Maybe there are people here with the appropriate engineering knowledge who have analyzed the design of the X6100's audio path and have some thoughts? Maybe, to some extent, this is an issue that could be addressed at the software/firmware level as well.

73 de Jarek SP9HGN

Hi. I'm using s/p mode set to "speaker" with my headphones (on R1CBU might be inverted, don't remember). With VOL ~10-20 it's comfortable to listening and less internal transceiver noise, in opposite to using "phone" mode.

It also possible to set to zero output signal by patching firmware, for example - when AGC turned off. This might be helpful to determine source of noise - before or after DSP.

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Georgy // R2RFE

Yeah, I’ve also experimented with switching speaker/phone, but results are still not very satisfying. Especially, when I’m in an environment with low RF-noise (like in mountains) then this internal noise is noticeable and is covering a weak stations (not a matter of making weak station unreadable, but just annoying).

I’m not really sure what you mean by setting output signal to zero? This internal noises are even well heard when volume is set to zero, so I’m guessing it’s injected somewhere at the ?very end of audio path.

Now I think I also need to check if this internal noises are present in signal coming from x6100 soundcard…

While tuning a threshold for TX compressor I noticed, that radio generates more noise, when it powered from the internal battery. It might also affect RX noise. Also TX SNR is quite low - about 35 db from noise level to pure sine signal generated within firmware with enough level to generate expected TX power. I have few screenshots - TX on USB without noise cancelling and with it.

I noticed, that on 1.1.6 VOL control behaves different for values 0...30 and for values upper 30. Looks like for values below 30 - volume controlled by multiplying signal (in digital form) for some value, for values above 30? - with configuring output codec only. It might be worth to check noise with VOL above 30, perhaps, with additional attenuation, it might be a better SNR.

For my experience - sound from headphones sounds a bit better, than sound comes to MAIN board from BASE.

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Georgy // R2RFE

In my case, switching to external power is not giving any significant change to audio signal.
As an attachment I'm sending here two files:
x6100_noise_blank.mp3 - it's a noise recorded from x6100's internal sound card, with Line-out in R1CBU/R2RFE App/Settings set to 0 (to eliminate as much of RX noise as possible).

x6100_noise_qso.mp3 - is an audio recorded from x6100's internal sound card. It's a strong local station ragchewing @ 80m. Recording was done with RF gain setting from 0 to 70 to 0.

When using external speaker it's not annoying anyhow, but for headphones? with closed construction - it is. Especially, when trying? to catch weak station...

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Spectrum for this blank noise looks like this:

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That's interesting... tomorrow I'll try to make simple external attenuator for my headphones, and will? do some experimentations with volume settings above 30.

I recorded some noises. Transceiver was not connected to antenna.

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rfg 0 vol 0..55 speaker - rfg set to 0, recorded from headphones/speaker output (configured for speaker) with my PC internal soundcard (line-in), changing vol from 0 to 55.

rfg 63 vol 0..55 speaker - same as above, but RFG 63

rfg 63 vol 0...55 headphones - same as above, but output configured as headphones

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usb soundcard, lineout 0..36, rfg 63 - recorded using USB soundcard within transceiver, rfg 63, line-out value changed from 0 to 36 within transceiver.

usb soundcard, lineout 10, rfg 63...0 - same as above, but line-out 10, rfg changed from 0 to 63.

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Can't record using application (seems, I broke something, while building base image last time)

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Summary for my radio:

* For speaker/phones I can hear noise Jarek mentioned, but its level is not so big (at least for my opinion). Changing S/P mode is not affects level.

* Phones mode makes volume lower, but generates more high-frequency noise on a big volume. I guess, it's a noise of the output audio amplifier.

* usb soundcard noise is significant higher, its level remains almost the same while changing frg/line-out

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I guess the noise is "applied" somewhere after DSP, when audio signal converted to analog form and traveling between codec output and speaker/headphones amplifier (and usb soundcard input).

It might be a noise through power line of audio amplifier/usb soundcard of interference to audio signal line. Adding some filtering to power line (with capacitor or LC filter) for amplifier and usb soundcard might help. Second option - using a short shielded cable to connect DAC output with amplifier input, but it might be a tricky without a schema.

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Georgy // R2RFE