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AGC Again [fixed in v1.441]

Hi John,

I know we have discussed AGC settings and possibly implementing a bandwidth defined threshold in previous threads.

However I've just had to clear the cookies in my browser, and I notice that the default AGC threshold seems to be back at -130dB, which means that for most users of KiWi's the AGC is effectively running disabled and as a consequence the background noise level is higher than it really needs to be.

I'm fairly sure that in the past the default value used to be -90dB.

I've got a fairly low noise floor and -90dB for USB bandwidth is just enough to reduce the background noise level without degrading the sensitivity, so I think this would be OK for most users.

Regards,

Martin - G8JNJ
Tony1951

Comments

  • I should have added.

    I think the term AGC threshold may be misleading. I'd expect that if you reduced the AGC threshold level down to say -130dB, it would be operating all the time, but actually the opposite seems true, as you increase the threshold value the gain is reduced.

    Try listening to a weak SSB signal and adjust the AGC threshold. There should be a point where the background noise is reduced but the intelligibility remains the same.

    Tune to a CW signal and observe the decoder threshold graph whilst adjusting the AGC threshold. You can see the background noise fall away and the CW becomes much more consistant.

    Maybe the default AGC threshold value should be in the Admin setup, so that it can be adjusted for the site noise floor.

    Regards,

    Martin - G8JNJ
    Tony1951
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