Background noise

[Ron Patton]

Hi,

Attached is a recording I made today of a RADE transmission (K0PFX).  There is a persistent noise in the background (the noise is difficult for me to describe,  but it is similar to what you would hear if FreeDV is set to Analog mode).   This is not new at for me as I think I have always heard the background noise (but actually I have lost track of the number of versions I have tested). The version of FreeDV is 2.0.1-dev-06f0.  

Please down load the file (unzip it) and play it.  The noise is obvious in the background.

73,

Ron

[Ron Patton]

Note:  I hear the noise on all received stations, not just the one in the recording.

[Mooneer Salem]

Hi Ron,

Do you happen to have anything enabled in Tools->Filter by any chance (either the microphone or speaker tabs)? If so, try disabling the filters and see if that makes any difference.

Thanks,

-Mooneer K6AQ

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[Barry Jackson]

> a5be71a1de1dn%40googlegroups.com?utm_medium=email&utm_source=footer>.

That transmission sounds fine to me.
It decodes without any noticeable background noise.

If this is playing back with the raw off-air signal mixed with the
decoded audio then I suspect that you have a system audio configuration
issue.

[Ron Patton]

I was in a QSO with K0PFX just a bit ago.  It seems there is problem somewhere in his audio path.  When he played his CQ audio file ("Voice Keyer"),  the audio was perfect (no background artifacts).  Only when he is live with his microphone does the noise occur.  I was in QSO with another station (AE2NY) and his audio was perfect (no background artifacts).  But I do need to mention that both K0PFX and I are running development versions (2.0.1.xxxx) and AE2NY is not.  

73,

Ron

[Mooneer Salem]

As a general reminder, it's a good idea not to overdrive your microphone, regardless of whether you're using RADE or another voice mode. Usually your OS has something in the sound settings that will show how loud your voice is when you're talking to allow proper adjustment of levels.

Re: 2.0.1 -- I haven't heard of any other similar issues yet but if it turns out some change in the upcoming release is related, we can definitely investigate further. 

-Mooneer K6AQ 

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[Ed Marciniak]

Some PC audio hardware includes a hardware AGC. It would not be entirely unreasonable to add a disabled by default AGC component.

When available, people should use it.

You can’t really get around the negative effects of limited ADC resolution if a signal has to be boosted, effectively losing several bits on a software AGC. It still might be better than too low(or high) input to the vocoder. Making people aware of it with under-range/over-range status indicators that ignore gaps between words might lead them to better adjust levels or get better audio hardware.

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From: digita...@googlegroups.com <digita...@googlegroups.com> on behalf of Mooneer Salem <moo...@gmail.com>
Sent: Wednesday, July 16, 2025 12:46:24 AM
To: digitalvoice <digita...@googlegroups.com>
Subject: Re: [digitalvoice] Re: Background noise

 

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