[hpsdr] SDR Dynamic Range Considerations

[Tayloe Dan-P26412]

I would hope that a SDR detector would have the option go straight into
the A/D converters without an additional op-amp to add unnecessary
distortion and noise. 

- Dan, N7VE

-----Original Message-----
From: Philip Covington [mailto:p.covington at gmail.com] 
Sent: Tuesday, February 20, 2007 6:15 PM
To: Tayloe Dan-P26412
Cc: hpsdr at hpsdr.org
Subject: Re: [hpsdr] SDR Dynamic Range Considerations

On 2/20/07, Tayloe Dan-P26412 <Dan.Tayloe at motorola.com> wrote:
<snip>
> I did not find the input impedance specs of the AKM5394A A/D 
> converter, but I assume it is reasonably high compared to the 200 ohms

> out of the detector.  If they are high impedance, the detector R/C 
> roll off ought to be pretty good as opposed to connecting to a normal 
> op-amp, which does decrease the single pole R/C roll-off
effectiveness.

Hi Dan,

Hopefully Bill, Phil or Lyle will correct me if I am wrong, but as I
recall the input impedance of JANUS is around 100k ohms.  That is into
the LT1128 op amps.

73 Phil N8VB

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