[time-nuts] Software defined spectrum analyzer

jimlux jimlux at earthlink.net
Sat Dec 11 23:10:46 UTC 2010


Luis Cupido wrote:
> Hi Don.
> 
> I'm ultra curious of how they did it. How did they covered the
> full BW they have.
> Did you looked inside, or did they sent a block diagram?
> (...I was born curious... it is not a new symptom!)
> 
> Luis Cupido.
> ct1dmk.
> 

the manual is on the website..
some clues

Intermediate frequencies of 2.9 MHz and 10.7 MHz are used for all 
frequencies. An RF input signal near these frequencies may generate 
spurious responses and degrade the performance of the image rejection 
algorithm.


Chapter 5 of the manual has the whole block diagram.. basically it's a 
240kHz wide sampler, with a single/double conversion front end and a 
bunch of switches.  They do some clever signal processing in software 
too, by stepping the LO and combining FFTs...



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