GNU Radio 3.6.4.1 C++ API
gr_pfb_interpolator_ccf Class Reference

Polyphase filterbank interpolator with gr_complex input, gr_complex output and float taps. More...

#include <pfb_interpolator_ccf.h>

Inheritance diagram for gr_pfb_interpolator_ccf:
gr_sync_interpolator gr_sync_block gr_block gr_basic_block gr_msg_accepter gruel::msg_accepter

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
- Public Member Functions inherited from gr_sync_interpolator
unsigned interpolation () const
void set_interpolation (unsigned interpolation)
void forecast (int noutput_items, gr_vector_int &ninput_items_required)
 Estimate input requirements given output request.
int general_work (int noutput_items, gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
 compute output items from input items
int fixed_rate_ninput_to_noutput (int ninput)
 Given ninput samples, return number of output samples that will be produced. N.B. this is only defined if fixed_rate returns true. Generally speaking, you don't need to override this.
int fixed_rate_noutput_to_ninput (int noutput)
 Given noutput samples, return number of input samples required to produce noutput. N.B. this is only defined if fixed_rate returns true. Generally speaking, you don't need to override this.

Friends

GR_CORE_API
gr_pfb_interpolator_ccf_sptr 
gr_make_pfb_interpolator_ccf (unsigned int interp, const std::vector< float > &taps)

Additional Inherited Members

- Public Types inherited from gr_block
enum  { WORK_CALLED_PRODUCE = -2, WORK_DONE = -1 }
 Magic return values from general_work. More...
enum  tag_propagation_policy_t { TPP_DONT = 0, TPP_ALL_TO_ALL = 1, TPP_ONE_TO_ONE = 2 }
- Protected Types inherited from gr_basic_block
enum  vcolor { WHITE, GREY, BLACK }
- Protected Member Functions inherited from gr_sync_interpolator
 gr_sync_interpolator (void)
 gr_sync_interpolator (const std::string &name, gr_io_signature_sptr input_signature, gr_io_signature_sptr output_signature, unsigned interpolation)
- Protected Attributes inherited from gr_block
std::vector< long > d_max_output_buffer
std::vector< long > d_min_output_buffer
gruel::mutex d_setlock

Detailed Description

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 floating-point 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 low-pass filter with a sampling rate of fs, a 3-dB bandwidth of BW and a transition bandwidth of TB. We can also specify the out-of-band attenuation to use, ATT, and the filter window function (a Blackman-harris 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 = filter.firdes.low_pass_2(interp, interp*fs, BW, TB, attenuation_dB=ATT, window=filter.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.

Constructor & Destructor Documentation

gr_pfb_interpolator_ccf::~gr_pfb_interpolator_ccf ( )

Member Function Documentation

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

Parameters
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.

Friends And Related Function Documentation

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.

Parameters
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.

The documentation for this class was generated from the following files: