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. 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:

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

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

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