GNU Radio C++ API
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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 | |
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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 | |
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gr_sync_interpolator (const std::string &name, gr_io_signature_sptr input_signature, gr_io_signature_sptr output_signature, unsigned interpolation) | |
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gr_sync_block (void) | |
gr_sync_block (const std::string &name, gr_io_signature_sptr input_signature, gr_io_signature_sptr output_signature) | |
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gr_block (void) | |
gr_block (const std::string &name, gr_io_signature_sptr input_signature, gr_io_signature_sptr output_signature) | |
void | set_fixed_rate (bool fixed_rate) |
void | add_item_tag (unsigned int which_output, uint64_t abs_offset, const pmt::pmt_t &key, const pmt::pmt_t &value, const pmt::pmt_t &srcid=pmt::PMT_F) |
Adds a new tag onto the given output buffer. | |
void | add_item_tag (unsigned int which_output, const gr_tag_t &tag) |
Adds a new tag onto the given output buffer. | |
void | get_tags_in_range (std::vector< gr_tag_t > &v, unsigned int which_input, uint64_t abs_start, uint64_t abs_end) |
Given a [start,end), returns a vector of all tags in the range. | |
void | get_tags_in_range (std::vector< gr_tag_t > &v, unsigned int which_input, uint64_t abs_start, uint64_t abs_end, const pmt::pmt_t &key) |
Given a [start,end), returns a vector of all tags in the range with a given key. | |
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gr_basic_block (void) | |
gr_basic_block (const std::string &name, gr_io_signature_sptr input_signature, gr_io_signature_sptr output_signature) | |
Protected constructor prevents instantiation by non-derived classes. | |
void | set_input_signature (gr_io_signature_sptr iosig) |
may only be called during constructor | |
void | set_output_signature (gr_io_signature_sptr iosig) |
may only be called during constructor | |
void | set_color (vcolor color) |
Allow the flowgraph to set for sorting and partitioning. | |
vcolor | color () const |
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).
<B><EM>self._taps = gr.firdes.low_pass_2(interp, interp*fs, BW, TB, attenuation_dB=ATT, window=gr.firdes.WIN_BLACKMAN_hARRIS)</EM></B>
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. |
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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.
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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. |