[time-nuts] Software defined spectrum analyzer

jimlux jimlux at earthlink.net
Sun Dec 12 01:31:31 UTC 2010


Don Latham wrote:
> Hi Luis:I, too, am curious. But I haven't opened it yet. I suspect
> something like an FPGA feeding a fast a/d somewhere in the 50-70 MHz
> range. That is, a decomposition.
> There may be a synthesized LO and mixer to get to the 50 MHz.
> The info on the website says or used to say something about an sdr
> modified to act as a spectrum analyzer.
> One of the things I like about the device that played a part in my
> purchase is the availability of a 10 MHz reference input. as a good
> time-nut that shows some serious engineering attention to accuracy.
> Don
> 

I'm going to guess much simpler inside.. Essentially a programmable 
receiver like the Icom PCR1000, but with better bandwidth, running into 
a pair of 192kHz ADCs, for which easy USB interfacing is available.

The question is really what does the 4GHz LO in the front look like? 
It's almost certainly some sort of VCO PLL scheme, probably with 
multiple VCOs. But, do they use a DDS?  Probably not... They probably 
have a fast PLL that settles quickly so they step through in 100 kHz 
steps or so.




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