[eagle] Re: 70 cm baseband data from 70 cm Receiver

Robert McGwier rwmcgwier at gmail.com
Wed Jun 20 20:51:34 PDT 2007


Juan:

We are using a quadrature sampling mixer at 10.7 MHz IF.  Consider it a 
roofing filter and mixer in one simple package.  We will set the 
bandwidth appropriately.  If the impedance is matched to the output of 
the receiver,  it will have very large rejection anywhere outside of the 
passband of the receiver.  The A/D will operate at D.C. and not at 10.7 
MHz if.

Bob

Juan Rivera wrote:
> All,
> 
> I'm not trying to beat this to death but I want to make sure I fully
> understand what I'm looking at here...
> 
> I spent some time this evening looking at the spectrum between the 10.7 MHz
> IF output and zero Hertz.  I did this because I believe it may be a
> significant area of interest since the receiver will feed an analog to
> digital converter.  The A/D converte

r is not a tuned stage so it will
> digitize baseband noise along with the IF signal.  I've been told that the
> impact of noise in the baseband is to reduce the dynamic range in the
> digital domain.  I'd appreciate an explanation since I am woefully ignorant
> in this area.
> 
> I posted my results in the usual area.  Just scroll down till you come to
> today's date.
> 
> 73,
> 
> Juan
> 
> 
> _______________________________________________
> Via the Eagle mailing list courtesy of AMSAT-NA
> Eagle at amsat.org
> http://amsat.org/mailman/listinfo/eagle
> 


-- 
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
"If you're going to be crazy, you have to get paid for it or
else you're going to be locked up." Hunter S. Thompson


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