Sloped AGC

[Bill W4ZV]

K8ZOA:
 >You might be interested in the AGC input versus output performance data
I  took for the K2 and several other receivers.

http://www.cliftonlaboratories.com/receiver_agc_curves.htm

 >To some extent, the K2 already implements this feature. Whether this is
an intentional design decision or a byproduct of other decisions made
during the K2's design, I do not know. In my opinion, it is one of the
reasons for the distinct "K2 sound."

         Jack that's very interesting information!  Since
the K3 is implementing AGC digitally via DSP rather than via
analog means as in the K2, it it likely the K3's curve will be
much more similar to the Racal 6790.  It will be possible to
change the slope beyond the threshold but there will still be
a rather sharp transition right at the inflection point.

         Orion's original AGC was also very similar to the
Racal 6790 curve...a constant rate up to the threshold and
then perfectly flat beyond it.  This was probably W8JI's
major complaint about Orion.  Ten-Tec recently added Sloped
AGC after the new Yaesu rigs (9000 and 2000) rigs offered it.
However, even with sloped AGC as implemented in all of these
rigs, there will still be a very sharp transition right at
the threshold, which the K2 does not exhibit in your graph.

         I believe a challenge for Lyle KK7P might be to implement
sloped AGC in K3 using a multi-segmented approximation to the
K2's very soft AGC curve.  Since this might be possible in
the DSP firmware, I feel it is certainly worth investigating!

                                         73,  Bill  W4ZV







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[Jack Smith-6]

I have two DSP-based receivers, a Watkins-Johnson HF-1000 and a Kenwood
TS-870, but both are upstairs and attached to my radio desk with about
six bazillion wires and the test gear is all in the basement. So, one of
these days, I'll drag one or the other of these to the basement and run
some tests.

Jack



Bill Tippett wrote:

> K8ZOA:
> >You might be interested in the AGC input versus output performance data
> I  took for the K2 and several other receivers.
>
> http://www.cliftonlaboratories.com/receiver_agc_curves.htm
>
> >To some extent, the K2 already implements this feature. Whether this is
> an intentional design decision or a byproduct of other decisions made
> during the K2's design, I do not know. In my opinion, it is one of the
> reasons for the distinct "K2 sound."
>
>         Jack that's very interesting information!  Since
> the K3 is implementing AGC digitally via DSP rather than via
> analog means as in the K2, it it likely the K3's curve will be
> much more similar to the Racal 6790.  It will be possible to
> change the slope beyond the threshold but there will still be
> a rather sharp transition right at the inflection point.
>
>         Orion's original AGC was also very similar to the
> Racal 6790 curve...a constant rate up to the threshold and
> then perfectly flat beyond it.  This was probably W8JI's
> major complaint about Orion.  Ten-Tec recently added Sloped
> AGC after the new Yaesu rigs (9000 and 2000) rigs offered it.
> However, even with sloped AGC as implemented in all of these
> rigs, there will still be a very sharp transition right at
> the threshold, which the K2 does not exhibit in your graph.
>
>         I believe a challenge for Lyle KK7P might be to implement
> sloped AGC in K3 using a multi-segmented approximation to the
> K2's very soft AGC curve.  Since this might be possible in
> the DSP firmware, I feel it is certainly worth investigating!
>
>                                         73,  Bill  W4ZV
>
>
>
>
>
>
>
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> You must be a subscriber to post to the list.
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