[Elecraft] K3 DSP AGC Question

[Guy Olinger K2AV]

It may be a dance, but hopefully careful intelligent musing over the
matter is convincing people that they should get the ambient well down
in the analog-to-digital converter (ADC) operating range. If they do,
a -99 threshold is a -109 threshold, and further backing off RF gain
can make it a -119 or -129 threshold as far as the ADC is concerned,
and headroom is being used for what headroom should be used for.

One thing for sure, there has not been a good-enough presentation of
what is going on, and people really don't seem to get it.  For
something that is plain indisputable physics, people are still running
PRE and max RFgain on 80 with fast AGC, and are honestly dismayed and
confused about the inevitable outcome, incorrectly blaming the rig for
being natively noisy, no-work NR and NB, filter "ringing", unable to
pull signals out of noise, and more.

Maybe the variable gain by band in the MP (with a menu override) was
really a better strategy for a default. This same issue dogged Orion
owners, and by the chatter a lot of them never understood either.

There IS something entirely separate with the headphone audio and HI-Z
headsets, high volume levels, maybe a sharp saturation point, and
mush, just haven't nailed it yet.

73, Guy.

On Mon, Feb 8, 2010 at 12:01 PM, Joe Subich, W4TV <lists at subich.com> wrote:
>
>
>> Likely?  I don't know.
>
> Likely is a better choice since raising the AGC threshold
> seems to be the primary goal of much of the "PRE/ATT/RF
> Gain dance" we've seen recently.
>
> The hardware AGC (HAGC) would seem to provide an ultimate
> limit on level to the ADC - unless the ADC can't handle
> the transient peaks - so a higher threshold for the DSP
> derived AGC would be helpful in many ways.
>
> 73,
>
>   ... Joe, W4TV
>
>
>
>
>> -----Original Message-----
>> From: elecraft-bounces at mailman.qth.net
>> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Lyle Johnson
>> Sent: Monday, February 08, 2010 11:24 AM
>> To: elecraft at mailman.qth.net
>> Subject: Re: [Elecraft] K3 DSP AGC Question
>>
>>
>> Hello Joe!
>> > Assuming that the threshold values have not changed in a major
>> > way since Jack's measurements, would it be possible to extend
>> > the range of threshold values - say to AGC THR=016 at about
>> > -80dBm (assuming 2 dB per step)?
>> >
>>
>> Possible?  Yes.
>>
>> Likely?  I don't know.  There are a lot of side effects that
>> happen when the threshold is raised...
>>
>> 73,
>>
>> Lyle KK7P
>>
>
>
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