http://elecraft.85.s1.nabble.com/K3-in-a-cw-pileup-needs-work-tp4523884p4535086.html
measured by Jack Smith ... as well as numbers reported by
Sherwood for the FT-1000D, FT-1000MP and even the IC-7600.
... Joe, W4TV
> -----Original Message-----
> From:
[hidden email]
> [mailto:
[hidden email]] On Behalf Of Lyle Johnson
> Sent: Sunday, February 07, 2010 2:21 PM
> To: Guy Olinger K2AV
> Cc:
[hidden email]
> Subject: Re: [Elecraft] K3 DSP AGC Question
>
>
>
> > Some follow-on questions:
> >
> > 1) When you say "The DSP outputs a voltage to control the
> IF gain of
> > the radio." are you referring to VIFGAIN1 input to U3B on the RF
> > board?
> >
>
> Yes.
> > 2) Assuming so, is there anything that influences the voltage on
> > VIFGAIN1 other than on behalf of the RF gain pot, and is
> the voltage
> > appearing at VFGAIN1 on behalf of the RF gain pot "processed" away
> > from a linear replication of the pot wiper voltage?
> >
> Without staring at the DSP code to verify the veracity of my reply, I
> recall that the RF Gain control is the only thing that
> currently drives
> the VIFGAIN1 voltage. Subject to change, of course, since it
> is a DSP
> firmware function. And yes, the value read from the pot is
> processed by
> the DSP on its way to becoming VIFGAIN1. Again, the
> algorithm applied
> is subject to change.
> > 3) The hardware AGC appears to have fixed slope, attack and decay
> > constants. What would be the DSP slope and decay config
> constants to
> > mimic the hardware AGC constants?
> >
> Correct as to the first, and I think there may be that there are no
> settings that exactly mimic the HAGC. Their purposes are quite
> different. To the DSP, influences of the HAGC voltage on the
> received
> signal are treated no differently than changes in propagation.
> > 4) Is there a table that provides a dBm equivalent of each of the
> > threshold values? Or alternatively are the values on the
> Clifton Labs
> > site correct?
> >
> > ( 2 -117 dBm
> > 3 -110.5 dBm
> > 4 -105 dBm
> > 5 -103.5 dBm
> > 6 -102.5 dBm
> > 7 -101 dBm
> > 8 -99 dBm )
> >
>
> There is no available table, and Jack's measurements were accurate at
> the time they were made for the then-current firmware release.
>
> 73,
>
> Lyle KK7P
>
>
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