K3 AGC Design Question

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K3 AGC Design Question

Don Rasmussen
Thanks very much Lyle!

I see (said the blind man).

So if you connected a meter to the hardware AGC you
would normally see no voltage at typical received
signal levels and that ADC might see increasing
voltage all the way up to it's tolerance before the
hardware AGC would jump in at with some hard value
(like turning on RF ATTN) to protect the ADC.

But none of this affects what the operator hears as
AGC or sees on the S Meter, that's all calculated from
the DSP. ?

Or does the DSP use any info from whats going on in
the analog stage to influence it's behavior and/or
displayed indications.

------------------------------------

[Elecraft] K3 AGC Design Question
Lyle Johnson kk7p at wavecable.com
Fri Sep 21 23:34:19 EDT 2007



> Question please - is the hardware AGC preceeding the
> DSP active only in excessive signal scenerios to
keep
> the DSP from becoming overloaded

Delete the word "only" and change DSP to ADC you've
got that part
correctly understood :-)  It is used to protect the IF
Analog to Digital
converter from over ranging under extreme signal
conditions.

> or can the hardware
> AGC be activated at normal signal levels by the K3
> firmware to work in conjunction with the AGC
algorithm
> in the DSP stage?

The DSP can intervene when appropriate.

73,

Lyle KK7P


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Re: K3 AGC Design Question

KK7P
> So if you connected a meter...

Let's just say the the hardware AGC does what it needs to do in a
carefully crafted way to protect the A to D.  The DSP observes and uses
this information as it performs its AGC and S Meter duties, and may
intervene.

There will be some detail in the service manual, but keep in mind that
the K3, though clearly created, will evolve :-) and the AGC will be part
of the evolution.

73,

Lyle KK7P

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