GNU Radio 3.6.5 C++ API

Polyphase filterbank interpolator with gr_complex input, gr_complex output and float taps. More...
#include <gr_pfb_interpolator_ccf.h>
Public Member Functions  
~gr_pfb_interpolator_ccf ()  
void  set_taps (const std::vector< float > &taps) 
void  print_taps () 
int  work (int noutput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items) 
just like gr_block::general_work, only this arranges to call consume_each for you  
Friends  
GR_CORE_API gr_pfb_interpolator_ccf_sptr  gr_make_pfb_interpolator_ccf (unsigned int interp, const std::vector< float > &taps) 
Polyphase filterbank interpolator with gr_complex input, gr_complex output and float taps.
This block takes in a signal stream and performs interger up sampling (interpolation) with a polyphase filterbank. The first input is the integer specifying how much to interpolate by. The second input is a vector (Python list) of floatingpoint taps of the prototype filter.
The filter's taps should be based on the interpolation rate specified. That is, the bandwidth specified is relative to the bandwidth after interpolation.
For example, using the GNU Radio's firdes utility to building filters, we build a lowpass filter with a sampling rate of fs, a 3dB bandwidth of BW and a transition bandwidth of TB. We can also specify the outofband attenuation to use, ATT, and the filter window function (a Blackmanharris window in this case). The first input is the gain, which is also specified as the interpolation rate so that the output levels are the same as the input (this creates an overall increase in power).
self._taps = gr.firdes.low_pass_2(interp, interp*fs, BW, TB, attenuation_dB=ATT, window=gr.firdes.WIN_BLACKMAN_hARRIS)
The PFB interpolator code takes the taps generated above and builds a set of filters. The set contains interp number of filters and each filter contains ceil(taps.size()/interp) number of taps. Each tap from the filter prototype is sequentially inserted into the next filter. When all of the input taps are used, the remaining filters in the filterbank are filled out with 0's to make sure each filter has the same number of taps.
The theory behind this block can be found in Chapter 7.1 of the following book.
f. harris, "Multirate Signal Processing for Communication Systems</EM>," Upper Saddle River, NJ: Prentice Hall, Inc. 2004.
gr_pfb_interpolator_ccf::~gr_pfb_interpolator_ccf  (  ) 
void gr_pfb_interpolator_ccf::print_taps  (  ) 
Print all of the filterbank taps to screen.
void gr_pfb_interpolator_ccf::set_taps  (  const std::vector< float > &  taps  ) 
Resets the filterbank's filter taps with the new prototype filter
taps  (vector/list of floats) The prototype filter to populate the filterbank. The taps should be generated at the interpolated sampling rate. 
int gr_pfb_interpolator_ccf::work  (  int  noutput_items, 
gr_vector_const_void_star &  input_items,  
gr_vector_void_star &  output_items  
)  [virtual] 
just like gr_block::general_work, only this arranges to call consume_each for you
The user must override work to define the signal processing code
Implements gr_sync_block.
GR_CORE_API gr_pfb_interpolator_ccf_sptr gr_make_pfb_interpolator_ccf  (  unsigned int  interp, 
const std::vector< float > &  taps  
)  [friend] 
Build the polyphase filterbank interpolator.
interp  (unsigned integer) Specifies the interpolation rate to use 
taps  (vector/list of floats) The prototype filter to populate the filterbank. The taps should be generated at the interpolated sampling rate. 