GNU Radio C++ API
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a computationally efficient controllable DC blocker More...
#include <gr_dc_blocker_cc.h>
Public Member Functions | |
~gr_dc_blocker_cc () | |
int | get_group_delay () |
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 More... | |
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void | forecast (int noutput_items, gr_vector_int &ninput_items_required) |
Estimate input requirements given output request. More... | |
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 More... | |
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. More... | |
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. More... | |
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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. More... | |
virtual bool | start () |
Called to enable drivers, etc for i/o devices. More... | |
virtual bool | stop () |
Called to disable drivers, etc for i/o devices. More... | |
void | set_output_multiple (int multiple) |
Constrain the noutput_items argument passed to forecast and general_work. More... | |
int | output_multiple () const |
void | consume (int which_input, int how_many_items) |
Tell the scheduler how_many_items of input stream which_input were consumed. More... | |
void | consume_each (int how_many_items) |
Tell the scheduler how_many_items were consumed on each input stream. More... | |
void | produce (int which_output, int how_many_items) |
Tell the scheduler how_many_items were produced on output stream which_output . More... | |
void | set_relative_rate (double relative_rate) |
Set the approximate output rate / input rate. More... | |
double | relative_rate () const |
return the approximate output rate / input rate More... | |
uint64_t | nitems_read (unsigned int which_input) |
Return the number of items read on input stream which_input. More... | |
uint64_t | nitems_written (unsigned int which_output) |
Return the number of items written on output stream which_output. More... | |
tag_propagation_policy_t | tag_propagation_policy () |
Asks for the policy used by the scheduler to moved tags downstream. More... | |
void | set_tag_propagation_policy (tag_propagation_policy_t p) |
Set the policy by the scheduler to determine how tags are moved downstream. More... | |
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 |
std::string | name () const |
gr_io_signature_sptr | input_signature () const |
gr_io_signature_sptr | output_signature () const |
gr_basic_block_sptr | to_basic_block () |
virtual bool | check_topology (int ninputs, int noutputs) |
Confirm that ninputs and noutputs is an acceptable combination. More... | |
template<typename T > | |
void | set_msg_handler (T msg_handler) |
Set the callback that is fired when messages are available. More... | |
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gr_msg_accepter () | |
~gr_msg_accepter () | |
void | post (pmt::pmt_t msg) |
send msg to msg_accepter More... | |
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msg_accepter () | |
virtual | ~msg_accepter () |
Friends | |
GR_CORE_API gr_dc_blocker_cc_sptr | gr_make_dc_blocker_cc (int D, bool long_form) |
Additional Inherited Members | |
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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 } |
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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::string | d_name |
gr_io_signature_sptr | d_input_signature |
gr_io_signature_sptr | d_output_signature |
long | d_unique_id |
vcolor | d_color |
a computationally efficient controllable DC blocker
This block implements a computationally efficient DC blocker that produces a tighter notch filter around DC for a smaller group delay than an equivalent FIR filter or using a single pole IIR filter (though the IIR filter is computationally cheaper).
The block defaults to using a delay line of length 32 and the long form of the filter. Optionally, the delay line length can be changed to alter the width of the DC notch (longer lines will decrease the width).
The long form of the filter produces a nearly flat response outside of the notch but at the cost of a group delay of 2D-2.
The short form of the filter does not have as flat a response in the passband but has a group delay of only D-1 and is cheaper to compute.
The theory behind this block can be found in the paper:
R. Yates, "DC Blocker Algorithms," IEEE Signal Processing Magazine, Mar. 2008, pp 132-134.
gr_dc_blocker_cc::~gr_dc_blocker_cc | ( | ) |
int gr_dc_blocker_cc::get_group_delay | ( | ) |
Get the blocker's group delay that is based on length of delay lines
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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 DC blocker.
D | (int) the length of the delay line |
long_form | (bool) whether to use long (true, default) or short form |