USAGE:

     fwwd-spectrum <file> [-L<label>] [options] FILTER <filter parameters>

PURPOSE:
Investigate Kaiser-Bessel low-pass filter properties, which are
Up to three filter parameters can be varied in one call, which are
The investigation is carried out for two cases,
A data file
The idealistic response
Since we know that the pass-band is inevitably deficient near the corner, a critical bandwidth
can be specified within which your significant signals will be located. This is especially
useful in the first stages of a cascaded filter chain.

The protocol output (STDOUT) can be filtered to retain lines containing '>R>' (and '>r>')
with the test results.
     An example for output, filtered with
     | fgrep -i '>R>'
 <Main-->r> T   lfp   wdp       f2     ::      ecc_        ecb_        ecp_       ecs_[dB]   f0|f-80    fnyd
 <Main-->r> __________________________________________________________________________________________________
 <Main-->R> R    48 2.5000  7.5000E-02 ::   -83.830084  -88.774883   -8.042363  -85.506738    0.1016    0.1000
 <Main-->R> I    48 2.5000  7.5000E-02 ::   -84.715148  -85.625079   -7.013949  -91.949932    0.0505    0.1000
 <Main-->R> R    48 2.5000  7.6000E-02 ::   -78.543322  -86.295376   -8.294929  -79.341050    0.1026    0.1000
 <Main-->R> I    48 2.5000  7.6000E-02 ::   -81.561380  -83.451222   -7.237595  -86.085679    0.0513    0.1000
 <Main-->R> R    48 2.5000  7.7000E-02 ::   -72.627879  -85.166479   -8.550657  -72.876947    0.1036    0.1000
 <Main-->R> I    48 2.5000  7.7000E-02 ::   -78.016671  -82.533702   -7.472965  -79.910481    0.0522    0.1000
 <Main-->R> R    48 2.5000  7.8000E-02 ::   -67.253276  -85.038665   -8.809983  -67.326203    0.1045    0.1000
 <Main-->R> I    48 2.5000  7.8000E-02 ::   -73.886105  -82.588202   -7.721120  -74.515097    0.0533    0.1000
 <Main-->R> R    48 2.5000  7.9000E-02 ::   -62.521246  -85.852209   -9.073524  -62.541462    0.1055    0.1000
 <Main-->R> I    48 2.5000  7.9000E-02 ::   -69.646417  -83.592710   -7.983211  -69.825089    0.0544    0.1000
 <Main-->R> R    48 2.5000  8.0000E-02 ::   -58.326189  -87.773801   -9.342091  -58.331124    0.1065    0.1000
 <Main-->R> I    48 2.5000  8.0000E-02 ::   -65.638305  -85.764912   -8.260474  -65.680693    0.0555    0.1000
 <Main-->R> R    48 2.5000  8.1000E-02 ::   -54.562759  -91.402638   -9.616693  -54.563658    0.1075    0.1000
 <Main-->R> I    48 2.5000  8.1000E-02 ::   -61.956175  -89.855042   -8.554236  -61.963226    0.0567    0.1000
 <Main-->R> R    48 2.5000  8.2000E-02 ::   -51.150620  -99.023815   -9.898550  -51.150691    0.1085    0.1000
 <Main-->R> I    48 2.5000  8.2000E-02 ::   -58.589847  -99.103427   -8.865907  -58.590233    0.0577    0.1000
 <Main-->R> R    48 2.5000  8.3000E-02 ::   -48.030581 -101.028201  -10.189081  -48.030603    0.1095    0.1000
 <Main-->R> I    48 2.5000  8.3000E-02 ::   -55.502906  -96.832362   -9.196987  -55.503225    0.0588    0.1000
 <Main-->R> R    48 2.5000  8.4000E-02 ::   -45.158546  -92.511709  -10.489910  -45.158626    0.1106    0.1000
 <Main-->R> I    48 2.5000  8.4000E-02 ::   -52.658355  -89.324107   -9.549056  -52.659291    0.0598    0.1000
The rows tagged I show the results with the ideal band-pass as the objective.
The rows tagged R show the results from real data.
The result columns are (in dB-units unless stated otherwise) 
All these results are integral deficiencies, summed up over the respective frequency ranges

Dimensionless frequencies, Nyquist fny = 0.5 for the input,
     Filter series are output to a binary file tmp/fwwd-test.fs
     and filter spectra (a real-valued series tagged FSP) to tmp/fwwd-test.fsp (to change, use option -o).

     The subroutines (sas/p/fwwd-iterate.f) permit backtransform and complex-spectrum output, of which no
     or only limited use is presently made.  


OPTIONS:

 -Tn               - Truncate the data series to contain n samples.

 -Xn               - Extend the time domain with n (to avoid circular correlation).

 -C[y]a,p,ph[,S=s] - Can be repeated: A cosine generator with amplitude a, period p, and phase ph [deg].
                     p is assumed in the unit signified by y: h for hours (default), m for minutes or s for seconds.
                     s is a sweep parameter: the start and end frequencies differ by this relative amount (default = 0.1),
                     a broadened spectral feature is thus produced instead of a sharp line.

 -Du[,tcr]         - The undersampling rate, an integer  u > 1
                     optionally followed by the period [h] of the critical part of the pass-band.

 -Pcp[,fcr]        - The penalty p for critical pass-band deficiency (default 1.0),
                     optionally followed by the frequency of the critical part of the pass-band.
 -Ppp              - The penalty p for whole pass-band deficiency (default 1.0)
 -Psp              - The penalty p for stop-band deficiency (default 1.0)
 
 -Ifn,df           - Vary the upper band corner (f2) with increment df 
 -Inn,dn           - Vary the filter length with increment (integer) dn
 -Iwn,dp           - Vary the window design parameter (wdp) with increment dp
                     In all -I options, the loop is starting with the respective parameter given in the FILTER arguments
                     and goes n rounds. Default is a single pass.

 -o<fnr>           - output files, name's path+root (extensions .fs .fsp .sp .ts will be added). Default=`tmp/fwwd-testยด
  
 -QDB              - A debug option, for use in code development.

 FILTER D:WD KAIS  - Just like it's stated in tsf-edit commands. Must be of type D:WD KAIS           


EXAMPLE:

   fwwd-spectrum d/G1_garb_190105-1s.mc -LG+B -X36000 -Cs200.,6.,0.,S=0.2 -D5 \
                 -Pc1.0,0.01666667 -Pp0.0 -Iw10,-0.05 -If10,0.001 \
                 FILTER D:WD KAIS 48 2.5 0.0 0.075 0.5 0.0

   splist -n~8.00e-2 -AdB tmp/fwwd-test.fsp FSP