pvsbandp — A band pass filter working in the spectral domain.


Filter the pvoc frames, passing bins whose frequency is within a band, and with linear interpolation for transitional bands.


fsig pvsbandp fsigin, xlowcut,
      xlowfull, xhighfull, xhighcut[, ktype]


fsig -- output pv stream

fsigin -- input pv stream.

xlowcut, xlowfull, xhighfull, xhighcut -- define a trapezium shape for the band that is passed. The a-rate versions only apply to the sliding case.

ktype -- specifies the shape of the transitional band. If at the default value of zero the shape is as below, with linear transition in amplitude. Other values yield and exponential shape:

(1 - exp( r*type )) / (1 - exp(type))

This includes a linear dB shape when ktype is log(10) or about 2.30.

The opcode performs a band-pass filter with a spectral envelope shaped like

     klowfull __________________________ khighfull
             /                          \
            /                            \
           /                              \
          /                                \
         /                                  \
________/                                    \______________
        klowcut                       khighcut


Example 347. Example

asig  in                                 ; get the signal in

fsig  pvsanal   asig, 1024, 256, 1024, 1 ; analyse it
ftps  pvsbandp  fsig, 200, 400, 1000, 2000 ; filter 300-1500Hz
atps  pvsynth   ftps                     ; synthesise it


Author: John ffitch
December 2007