.(L)OWPASS, (H)IGHPASS, OR (B)ANDPASS? (L/H/B):
[Enter type of the filter to be plotted]
.FERMI CUTOFF RADIUS, TEMP. FACTOR:
[Enter cutoff frequency and temperature factor.]
For Bandpass filter additional questions are asked:
.FERMI CUTOFF RADIUS.,TEMP.FACTOR:
[Enter cutoff frequency and temperature factor for the second
cutoff.]
.(L)OWPASS, (H)IGHPASS, OR (B)ANDPASS? (L/H/B):
[Enter type of the filter to be plotted]
.RADIUS:
[Enter cutoff frequency]
.(M)ULTIPLICATIVE,(A)DDITIVE:
[Enter type of the filter.]
.(L)OWPASS, (H)IGHPASS (L/H):
[Enter type of the filter to be plotted.]
.PASS-BAND AND STOP-BAND FREQUENCY:
[Enter the two frequencies.]
.LIKE AN EXAMPLE WITH STEP FUNCTION??(Y/N):
[If answer is"Y" then it gives the plot of a step function
and how does it look like when it is filtered using the
Butterworth filter with the given parameters.
NOTE: This currently works only for dimension (of plot)
equal to powers of two only.
If answer is "N" then you are back to operation command].
.NUMBER OF BANDS: 3
[Enter the number of pass- or stop- bands in freq. space
for a filter to be designed (at least 2).]
.BAND # i - LOWER AND UPPER EDGES: 0.1,0.14
[Enter the edges boundaries for each band.]
.BAND # i - DESIRED VALUE: 2.3
[Enter the desired filter for each band (e.g. 0.0 or 0.5 or
1.0 or 3.0).]
.BAND # i - WEIGHTING: 1
[Enter the weight for each band; this specifies the relative
error of approximation allowed in a given band]
.PLOT FREQUENCY RESPONSE (Y/N): Y
[Enter 'Y' if you want the plot of frequency response]
.DO YOU LIKE YOUR FILTER (Y/N): Y
[Enter 'Y' if you are satisfied with approximation obtained.
Otherwise you go back to the first step.]
.FILTER FILE: FIL001
[Enter name of file where filter is to be stored.]
.(NSAM,NROW): 128,64
[Enter dimensions of resulting filter in Fourier space.
If 0 then PSF is stored to be subsequently used in RC command
for real space filtering.]
.NUMBER OF SLICES (NSLICE): 32
[Enter number of slices for 3-D filter file. If 0 then a 2-D
filter is produced, if >0 then a 3-D filter.]
NOTES
kx=2*f*(nsam/2) f=0.5*kx/(nsam/2)For the description of the Remez exchange algorithm see any book on digital filter design. For the description of 2-D McClellan transformation algorithm see: 'Digital filters and their applications' Cappellini V., Constantinides A.G., Emiliani P. For the description of the Butterworth filter look at Signal processing algorithms Samuel D.Stearns, Ruth A.David.