K@ DSP Audio Filter Product Suggestion

[Fred Bennett-3]

Hi Gang

Having played with my new DSP gizmo I have come upon the
"Man, I wish I could" idea that would "seem" easy to
carry out. When setting up the audio filters, I would
like to be able to select GAIN settings for each filter
bandwidth. Right now, there are a possibility of 4 different
filter bandwidths....BUT they all share the same Gain setting.
If I could have different Gain settings for each filter
bandwidth, then I could set up a variable CW PEAKING filter
that could have progressively higher Gain for progressively
lower bandwidth. This would allow me to take a small slice
of the band and amplify the signal for really....really weak
signals!!!

   Any possibility???      73....de....Fred  N9TA


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[KK7P]

Hello Fred!

> ...  When setting up the audio filters, I would
> like to be able to select GAIN settings for each filter
> bandwidth...
> If I could have different Gain settings for each filter
> bandwidth, then I could set up a variable CW PEAKING filter
> that could have progressively higher Gain for progressively
> lower bandwidth. This would allow me to take a small slice
> of the band and amplify the signal for really....really weak
> signals!!!

This is an interesting idea.

A potential problem is that the KDSP2 is not really intended to provide
gain in the normal sense of amplification.  The gain adjustments are
intended solely to to provide equalization, so the apparent insertion
loss of the KDSP2 should be about 0 dB.

Here's why.

The input analog-to-digital converter has a certain maximum voltage that
it can accept from the product detector in the K2.  The output
digital-to-analog converter has the same voltage limit.  If you apply
too much internal gain in the DSP to a weak signal, and a strong signal
comes in, you may overdrive the digital-to-analog converter, resulting
in loud and unpleasant distortion.

The K2 AGC normally mitigates this by limiting the input signal to the
analog-to-digital converter, but some operators turn the AGC off.  With
the AGC off, the risk of unpleasant acoustic consequences increases!

Thus, I recommended setting the gains solely for equalization.  As you
narrow the DSP, just turn up the AF gain control on the K2 :-)

Enjoy!

Lyle KK7P


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[Fred Bennett-3]

   Exactly the idea! Surf the band in a higher bandwidth/
lower gain setting, and if you come across a weak signal
you want to "pop out" you go to a progressively lower
bandwidth/higher gain Afil. However, if you have to leave
the gain at a high setting and you surf thru a load signal,
then unpleasant noises may result.  :-)

-----Original Message-----


This is an interesting idea.

A potential problem is that the KDSP2 is not really intended to provide
gain in the normal sense of amplification.  The gain adjustments are
intended solely to to provide equalization, so the apparent insertion
loss of the KDSP2 should be about 0 dB.

Here's why.

The input analog-to-digital converter has a certain maximum voltage that
it can accept from the product detector in the K2.  The output
digital-to-analog converter has the same voltage limit.  If you apply
too much internal gain in the DSP to a weak signal, and a strong signal
comes in, you may overdrive the digital-to-analog converter, resulting
in loud and unpleasant distortion.

The K2 AGC normally mitigates this by limiting the input signal to the
analog-to-digital converter, but some operators turn the AGC off.  With
the AGC off, the risk of unpleasant acoustic consequences increases!

Thus, I recommended setting the gains solely for equalization.  As you
narrow the DSP, just turn up the AF gain control on the K2 :-)

Enjoy!

Lyle KK7P




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