Spectrum Software
spacer
Industrial Strength Simulation
select:

divider

 

News:

Spectrum Software has released Micro-Cap 11, the eleventh generation of our SPICE circuit simulator.

For users of previous Micro-Cap versions, check out the new features available in the latest version. For those of you who are new to Micro-Cap, take our features tour to see what Micro-Cap has to offer.

 

divider

 

Fourier Window Functions

 

Window functions have been added to MC11 to facilitate signal selectivity. Here is a list of the new window functions.

Rectangular
Bartlett-Hann
Blackman
Blackman-Harris
Blackman-Nuttal
Cosine
Falttop
Gaussian
Hamming
Hanning
Kaiser
Lanscos
Nuttal
Triangular
Tukey

Window functions are useful in many ways but spectral analysis is one particularly useful function. Here is a circuit that has a source with which the sum of two closely spaced sinusoids.
Circuit for demonstrating the Fourier window functions

The sinusoids are:

1.0 volts at 1470.2meg
0.001 volts at 1560.2meg


If you run a Fourier analysis of the e1 voltage you get this:



Fourier plot



Only the 1.0volt 1470.2MHz signal is evident in the Fourier plot. Now apply a Blackman- Harris window and we get this:



Fourier plot



Now the .001 signal at about 1560MHz is evident. In this case several window functions would have been effective in showing the small signal. Here is a what the Flattop function produces:



Fourier plot



In this circuit Blackman, Gaussian, Nuttal, Blackman-Harris, Blackman-Nuttal, and Flattop all proved effective in showing the smaller signal.

 
Download Fall 2013 Circuit Files
Return to the main Newsletter page