[hpsdr] AGC

[Robert McGwier]

Ramakrishnan:

As with all things,  it depends.

On the QSD based narrow band receivers,  analog AGC is definitely 
contraindicated and would definitely not perform as well as the 
implementation I did of the Phil Harman dual channel digital agc 
proposal (with some testing and advice and code suggestions by Jeff 
Anderson, K6JCA).   The dynamic range afforded us by the QSD and the 
high end audio sound cards help us avoid the analog AGC.  This gives us 
the ability to anticipate large signals by at least two time constants 
in a simple proportional control system for the agc value on both the 
slow and fast channel AGC.  The latter was my contributing to the 
overall design.  You may read Phil's original proposal on the hamsdr web 
site document section.

On the high speed A/D end,  we will definitely benefit from some kind of 
gain control on the A/D to aid us in the effective  use of the available 
dynamic range on Mercury (LTC2208).

Bob
N4HY



Ramakrishnan Muthukrishnan wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> May be this is a really stupid question. Pardon my ignorance. Or
> probably this is already addressed, but I am unaware.
>
> Is there any plan to provide DSP-controlled AGC control voltage by
> using a DAC, which can drive a voltage controlled amplifier? If so,
> where will the DAC sit?
>
>   


-- 
AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats,
NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman
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