GNU Radio 3.6.3.1 C++ API
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Polyphase filterbank bandpass decimator with gr_complex input, gr_complex output and float taps. More...
#include <pfb_decimator_ccf.h>
Public Types | |
typedef boost::shared_ptr < pfb_decimator_ccf > | sptr |
Public Member Functions | |
virtual void | set_taps (const std::vector< float > &taps)=0 |
virtual std::vector < std::vector< float > > | taps () const =0 |
virtual void | print_taps ()=0 |
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virtual int | work (int noutput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)=0 |
just like gr_block::general_work, only this arranges to call consume_each for you | |
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. | |
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virtual | ~gr_block () |
unsigned | history () const |
void | set_history (unsigned history) |
bool | fixed_rate () const |
Return true if this block has a fixed input to output rate. | |
virtual bool | start () |
Called to enable drivers, etc for i/o devices. | |
virtual bool | stop () |
Called to disable drivers, etc for i/o devices. | |
void | set_output_multiple (int multiple) |
Constrain the noutput_items argument passed to forecast and general_work. | |
int | output_multiple () const |
bool | output_multiple_set () const |
void | set_alignment (int multiple) |
Constrains buffers to work on a set item alignment (for SIMD) | |
int | alignment () const |
void | set_unaligned (int na) |
int | unaligned () const |
void | set_is_unaligned (bool u) |
bool | is_unaligned () const |
void | consume (int which_input, int how_many_items) |
Tell the scheduler how_many_items of input stream which_input were consumed. | |
void | consume_each (int how_many_items) |
Tell the scheduler how_many_items were consumed on each input stream. | |
void | produce (int which_output, int how_many_items) |
Tell the scheduler how_many_items were produced on output stream which_output . | |
void | set_relative_rate (double relative_rate) |
Set the approximate output rate / input rate. | |
double | relative_rate () const |
return the approximate output rate / input rate | |
uint64_t | nitems_read (unsigned int which_input) |
Return the number of items read on input stream which_input. | |
uint64_t | nitems_written (unsigned int which_output) |
Return the number of items written on output stream which_output. | |
tag_propagation_policy_t | tag_propagation_policy () |
Asks for the policy used by the scheduler to moved tags downstream. | |
void | set_tag_propagation_policy (tag_propagation_policy_t p) |
Set the policy by the scheduler to determine how tags are moved downstream. | |
int | max_noutput_items () |
Return the maximum number of output items this block will handle during a call to work. | |
void | set_max_noutput_items (int m) |
Set the maximum number of ouput items htis block will handle during a call to work. | |
void | unset_max_noutput_items () |
Clear the switch for using the max_noutput_items value of this block. | |
bool | is_set_max_noutput_items () |
Ask the block if the flag is or is not set to use the internal value of max_noutput_items during a call to work. | |
void | expand_minmax_buffer (int port) |
long | max_output_buffer (size_t i) |
Returns max buffer size on output port i . | |
void | set_max_output_buffer (long max_output_buffer) |
Sets max buffer size on all output ports. | |
void | set_max_output_buffer (int port, long max_output_buffer) |
Sets max buffer size on output port port . | |
long | min_output_buffer (size_t i) |
Returns min buffer size on output port i . | |
void | set_min_output_buffer (long min_output_buffer) |
Sets min buffer size on all output ports. | |
void | set_min_output_buffer (int port, long min_output_buffer) |
Sets min buffer size on output port port . | |
gr_block_detail_sptr | detail () const |
void | set_detail (gr_block_detail_sptr detail) |
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virtual | ~gr_basic_block () |
long | unique_id () const |
long | symbolic_id () const |
std::string | name () const |
std::string | symbol_name () const |
gr_io_signature_sptr | input_signature () const |
gr_io_signature_sptr | output_signature () const |
gr_basic_block_sptr | to_basic_block () |
bool | alias_set () |
std::string | alias () |
pmt::pmt_t | alias_pmt () |
void | set_block_alias (std::string name) |
void | message_port_register_in (pmt::pmt_t port_id) |
void | message_port_register_out (pmt::pmt_t port_id) |
void | message_port_pub (pmt::pmt_t port_id, pmt::pmt_t msg) |
void | message_port_sub (pmt::pmt_t port_id, pmt::pmt_t target) |
void | message_port_unsub (pmt::pmt_t port_id, pmt::pmt_t target) |
virtual bool | message_port_is_hier (pmt::pmt_t port_id) |
virtual bool | message_port_is_hier_in (pmt::pmt_t port_id) |
virtual bool | message_port_is_hier_out (pmt::pmt_t port_id) |
pmt::pmt_t | message_ports_in () |
Get input message port names. | |
pmt::pmt_t | message_ports_out () |
Get output message port names. | |
void | _post (pmt::pmt_t which_port, pmt::pmt_t msg) |
bool | empty_p (pmt::pmt_t which_port) |
is the queue empty? | |
bool | empty_p () |
void | insert_tail (pmt::pmt_t which_port, pmt::pmt_t msg) |
pmt::pmt_t | delete_head_nowait (pmt::pmt_t which_port) |
pmt::pmt_t | delete_head_blocking (pmt::pmt_t which_port) |
msg_queue_t::iterator | get_iterator (pmt::pmt_t which_port) |
void | erase_msg (pmt::pmt_t which_port, msg_queue_t::iterator it) |
virtual bool | has_msg_port (pmt::pmt_t which_port) |
virtual bool | check_topology (int ninputs, int noutputs) |
Confirm that ninputs and noutputs is an acceptable combination. | |
template<typename T > | |
void | set_msg_handler (pmt::pmt_t which_port, T msg_handler) |
Set the callback that is fired when messages are available. | |
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gr_msg_accepter () | |
~gr_msg_accepter () | |
void | post (pmt::pmt_t which_port, pmt::pmt_t msg) |
send msg to msg_accepter on port which_port | |
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msg_accepter () | |
virtual | ~msg_accepter () |
Static Public Member Functions | |
static sptr | make (unsigned int decim, const std::vector< float > &taps, unsigned int channel) |
Additional Inherited Members | |
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enum | vcolor { WHITE, GREY, BLACK } |
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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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std::vector< long > | d_max_output_buffer |
std::vector< long > | d_min_output_buffer |
Polyphase filterbank bandpass decimator with gr_complex input, gr_complex output and float taps.
This block takes in a signal stream and performs interger down- sampling (decimation) with a polyphase filterbank. The first input is the integer specifying how much to decimate by. The second input is a vector (Python list) of floating-point taps of the prototype filter. The third input specifies the channel to extract. By default, the zeroth channel is used, which is the baseband channel (first Nyquist zone).
The channel parameter specifies which channel to use since this class is capable of bandpass decimation. Given a complex input stream at a sampling rate of fs and a decimation rate of decim, the input frequency domain is split into decim channels that represent the Nyquist zones. Using the polyphase filterbank, we can select any one of these channels to decimate.
The output signal will be the basebanded and decimated signal from that channel. This concept is very similar to the PFB channelizer (see gr_pfb_channelizer_ccf) where only a single channel is extracted at a time.
The filter's taps should be based on the sampling rate before decimation.
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 of the filter, which we specify here as unity.
self._taps = filter.firdes.low_pass_2(1, fs, BW, TB, attenuation_dB=ATT, window=filter.firdes.WIN_BLACKMAN_hARRIS)
The PFB decimator code takes the taps generated above and builds a set of filters. The set contains decim number of filters and each filter contains ceil(taps.size()/decim) 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 6 of the following book.
f. harris, "Multirate Signal Processing for Communication Systems," Upper Saddle River, NJ: Prentice Hall, Inc. 2004.
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static |
Build the polyphase filterbank decimator.
decim | (unsigned integer) Specifies the decimation rate to use |
taps | (vector/list of floats) The prototype filter to populate the filterbank. |
channel | (unsigned integer) Selects the channel to return [default=0]. |
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pure virtual |
Print all of the filterbank taps to screen.
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pure virtual |
Resets the filterbank's filter taps with the new prototype filter
taps | (vector/list of floats) The prototype filter to populate the filterbank. |
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pure virtual |
Return a vector<vector<>> of the filterbank taps