$129 spectrum analyzer Re: [Open-graphics] PCIe know-how?

[James Richard Tyrer]

James Richard Tyrer wrote:
> There is no filter response shape to worry about.
> 
This has always been a serious issue with an analog spectrum analyzer. 
In theory, it should be a Gaussian distribution.  This is not realizable 
because it would have to extent to infinity.  But even taking a 
polynomial distribution, it is still impossible to exactly realize a 
band pass filter with that response function.  And, the filter also 
needs to have linear phase response.  So, this -- the scan filter 
response shape -- is an important feature and something that is better 
in more expensive units.

I suspect that the band pass response shape in these devices is not 
anything near a Gaussian response or linear phase.

-- 
JRT