GNU Radio Manual and C++ API Reference  3.10.9.1
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gr::digital::decision_feedback_equalizer Class Referenceabstract

Decision Feedback Equalizer. More...

#include <gnuradio/digital/decision_feedback_equalizer.h>

Public Types

typedef std::shared_ptr< decision_feedback_equalizersptr
 
- Public Types inherited from gr::block
enum  work_return_t { 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 , TPP_CUSTOM = 3 }
 enum to represent different tag propagation policies. More...
 

Public Member Functions

virtual void set_taps (const std::vector< gr_complex > &taps)=0
 
virtual std::vector< gr_complextaps () const =0
 
virtual int equalize (const gr_complex *input_samples, gr_complex *output_symbols, unsigned int num_inputs, unsigned int max_num_outputs, std::vector< unsigned int > training_start_samples=std::vector< unsigned int >(0), bool history_included=false, gr_complex *taps=nullptr, unsigned short *state=nullptr)=0
 Public "work" function - equalize a block of input samples. More...
 
- Public Member Functions inherited from gr::sync_decimator
unsigned decimation () const
 
void set_decimation (unsigned decimation)
 
void forecast (int noutput_items, gr_vector_int &ninput_items_required) override
 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) override
 compute output items from input items More...
 
int fixed_rate_ninput_to_noutput (int ninput) override
 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) override
 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...
 
- Public Member Functions inherited from gr::sync_block
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 More...
 
- Public Member Functions inherited from gr::block
 ~block () override
 
unsigned history () const
 
void set_history (unsigned history)
 
void declare_sample_delay (int which, unsigned delay)
 
void declare_sample_delay (unsigned delay)
 
unsigned sample_delay (int which) const
 
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
 
bool output_multiple_set () const
 
void set_alignment (int multiple)
 Constrains buffers to work on a set item alignment (for SIMD) More...
 
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. 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...
 
void set_inverse_relative_rate (double inverse_relative_rate)
 Set the approximate output rate / input rate using its reciprocal. More...
 
void set_relative_rate (uint64_t interpolation, uint64_t decimation)
 Set the approximate output rate / input rate as an integer ratio. More...
 
double relative_rate () const
 return the approximate output rate / input rate More...
 
uint64_t relative_rate_i () const
 return the numerator, or interpolation rate, of the approximate output rate / input rate More...
 
uint64_t relative_rate_d () const
 return the denominator, or decimation rate, of the approximate output rate / input rate More...
 
mpq_class & mp_relative_rate ()
 return a reference to the multiple precision rational representation of 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...
 
int min_noutput_items () const
 Return the minimum number of output items this block can produce during a call to work. More...
 
void set_min_noutput_items (int m)
 Set the minimum number of output items this block can produce during a call to work. More...
 
int max_noutput_items ()
 Return the maximum number of output items this block will handle during a call to work. More...
 
void set_max_noutput_items (int m)
 Set the maximum number of output items this block will handle during a call to work. More...
 
void unset_max_noutput_items ()
 Clear the switch for using the max_noutput_items value of this block. More...
 
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. More...
 
void expand_minmax_buffer (int port)
 
long max_output_buffer (size_t i)
 Returns max buffer size on output port i. More...
 
void set_max_output_buffer (long max_output_buffer)
 Request limit on max buffer size on all output ports. More...
 
void set_max_output_buffer (int port, long max_output_buffer)
 Request limit on max buffer size on output port port. More...
 
long min_output_buffer (size_t i)
 Returns min buffer size on output port i. More...
 
void set_min_output_buffer (long min_output_buffer)
 Request limit on the minimum buffer size on all output ports. More...
 
void set_min_output_buffer (int port, long min_output_buffer)
 Request limit on min buffer size on output port port. More...
 
void set_blkd_input_timer_value (unsigned int timer_value_ms)
 DEPRECATED Configure the timer set when input is blocked port. More...
 
unsigned int blkd_input_timer_value ()
 DEPRECATED Returns timer value set when input is blocked. More...
 
void allocate_detail (int ninputs, int noutputs, const std::vector< int > &downstream_max_nitems_vec, const std::vector< uint64_t > &downstream_lcm_nitems_vec, const std::vector< uint32_t > &downstream_max_out_mult_vec)
 Allocate the block_detail and necessary output buffers for this block. More...
 
buffer_sptr replace_buffer (size_t src_port, size_t dst_port, block_sptr block_owner)
 Replace the block's buffer with a new one owned by the block_owner parameter. More...
 
float pc_noutput_items ()
 Gets instantaneous noutput_items performance counter. More...
 
float pc_noutput_items_avg ()
 Gets average noutput_items performance counter. More...
 
float pc_noutput_items_var ()
 Gets variance of noutput_items performance counter. More...
 
float pc_nproduced ()
 Gets instantaneous num items produced performance counter. More...
 
float pc_nproduced_avg ()
 Gets average num items produced performance counter. More...
 
float pc_nproduced_var ()
 Gets variance of num items produced performance counter. More...
 
float pc_input_buffers_full (int which)
 Gets instantaneous fullness of which input buffer. More...
 
float pc_input_buffers_full_avg (int which)
 Gets average fullness of which input buffer. More...
 
float pc_input_buffers_full_var (int which)
 Gets variance of fullness of which input buffer. More...
 
std::vector< float > pc_input_buffers_full ()
 Gets instantaneous fullness of all input buffers. More...
 
std::vector< float > pc_input_buffers_full_avg ()
 Gets average fullness of all input buffers. More...
 
std::vector< float > pc_input_buffers_full_var ()
 Gets variance of fullness of all input buffers. More...
 
float pc_output_buffers_full (int which)
 Gets instantaneous fullness of which output buffer. More...
 
float pc_output_buffers_full_avg (int which)
 Gets average fullness of which output buffer. More...
 
float pc_output_buffers_full_var (int which)
 Gets variance of fullness of which output buffer. More...
 
std::vector< float > pc_output_buffers_full ()
 Gets instantaneous fullness of all output buffers. More...
 
std::vector< float > pc_output_buffers_full_avg ()
 Gets average fullness of all output buffers. More...
 
std::vector< float > pc_output_buffers_full_var ()
 Gets variance of fullness of all output buffers. More...
 
float pc_work_time ()
 Gets instantaneous clock cycles spent in work. More...
 
float pc_work_time_avg ()
 Gets average clock cycles spent in work. More...
 
float pc_work_time_var ()
 Gets average clock cycles spent in work. More...
 
float pc_work_time_total ()
 Gets total clock cycles spent in work. More...
 
float pc_throughput_avg ()
 Gets average throughput. More...
 
void reset_perf_counters ()
 Resets the performance counters. More...
 
void setup_pc_rpc ()
 Sets up export of perf. counters to ControlPort. Only called by the scheduler. More...
 
bool is_pc_rpc_set () const
 Checks if this block is already exporting perf. counters to ControlPort. More...
 
void no_pc_rpc ()
 If the block calls this in its constructor, it's perf. counters will not be exported. More...
 
void set_processor_affinity (const std::vector< int > &mask) override
 Set the thread's affinity to processor core n. More...
 
void unset_processor_affinity () override
 Remove processor affinity to a specific core. More...
 
std::vector< int > processor_affinity () override
 Get the current processor affinity. More...
 
int active_thread_priority ()
 Get the current thread priority in use. More...
 
int thread_priority ()
 Get the current thread priority stored. More...
 
int set_thread_priority (int priority)
 Set the current thread priority. More...
 
bool update_rate () const
 
void system_handler (pmt::pmt_t msg)
 the system message handler More...
 
void set_log_level (const std::string &level) override
 Set the logger's output level. More...
 
std::string log_level () override
 Get the logger's output level. More...
 
bool finished ()
 returns true when execution has completed due to a message connection More...
 
block_detail_sptr detail () const
 
void set_detail (block_detail_sptr detail)
 
void notify_msg_neighbors ()
 Tell msg neighbors we are finished. More...
 
void clear_finished ()
 Make sure we don't think we are finished. More...
 
std::string identifier () const
 
- Public Member Functions inherited from gr::basic_block
pmt::pmt_t message_subscribers (pmt::pmt_t port)
 
 ~basic_block () override
 
long unique_id () const
 
long symbolic_id () const
 
std::string name () const
 
std::string symbol_name () const
 
std::string identifier () const
 
gr::io_signature::sptr input_signature () const
 
gr::io_signature::sptr output_signature () const
 
basic_block_sptr to_basic_block ()
 
bool alias_set () const
 
std::string alias () const
 
pmt::pmt_t alias_pmt () const
 
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. More...
 
pmt::pmt_t message_ports_out ()
 Get output message port names. More...
 
void _post (pmt::pmt_t which_port, pmt::pmt_t msg)
 
bool empty_p (pmt::pmt_t which_port)
 is the queue empty? More...
 
bool empty_p ()
 
bool empty_handled_p (pmt::pmt_t which_port)
 are all msg ports with handlers empty? More...
 
bool empty_handled_p ()
 
size_t nmsgs (pmt::pmt_t which_port)
 How many messages in the queue? More...
 
void insert_tail (pmt::pmt_t which_port, pmt::pmt_t msg)
 
pmt::pmt_t delete_head_nowait (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)
 
const msg_queue_map_t & get_msg_map (void) const
 
virtual void setup_rpc ()
 Set up the RPC registered variables. More...
 
bool is_rpc_set ()
 Ask if this block has been registered to the RPC. More...
 
void rpc_set ()
 When the block is registered with the RPC, set this. More...
 
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 (pmt::pmt_t which_port, T msg_handler)
 Set the callback that is fired when messages are available. More...
 
- Public Member Functions inherited from gr::msg_accepter
 msg_accepter ()
 
 ~msg_accepter () override
 
void post (pmt::pmt_t which_port, pmt::pmt_t msg) override
 send msg to msg_accepter on port which_port More...
 
- Public Member Functions inherited from gr::messages::msg_accepter
 msg_accepter ()
 

Static Public Member Functions

static sptr make (unsigned num_taps_forward, unsigned num_taps_feedback, unsigned sps, adaptive_algorithm_sptr alg, bool adapt_after_training=true, std::vector< gr_complex > training_sequence=std::vector< gr_complex >(), const std::string &training_start_tag="")
 Return a shared_ptr to a new instance of gr::digital::decision_feedback_equalizer. More...
 

Additional Inherited Members

- Protected Types inherited from gr::basic_block
enum  vcolor { WHITE , GREY , BLACK }
 
- Protected Member Functions inherited from gr::sync_decimator
 sync_decimator (void)
 
 sync_decimator (const std::string &name, gr::io_signature::sptr input_signature, gr::io_signature::sptr output_signature, unsigned decimation)
 
- Protected Member Functions inherited from gr::sync_block
 sync_block (void)
 
 sync_block (const std::string &name, gr::io_signature::sptr input_signature, gr::io_signature::sptr output_signature)
 
- Protected Member Functions inherited from gr::block
 block (void)
 
 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. More...
 
void add_item_tag (unsigned int which_output, const tag_t &tag)
 Adds a new tag onto the given output buffer. More...
 
void remove_item_tag (unsigned int which_input, uint64_t abs_offset, const pmt::pmt_t &key, const pmt::pmt_t &value, const pmt::pmt_t &srcid=pmt::PMT_F)
 DEPRECATED. Will be removed in 3.8. More...
 
void remove_item_tag (unsigned int which_input, const tag_t &tag)
 DEPRECATED. Will be removed in 3.8. More...
 
void get_tags_in_range (std::vector< 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. More...
 
void get_tags_in_range (std::vector< 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. More...
 
void get_tags_in_window (std::vector< tag_t > &v, unsigned int which_input, uint64_t rel_start, uint64_t rel_end)
 Gets all tags within the relative window of the current call to work. More...
 
void get_tags_in_window (std::vector< tag_t > &v, unsigned int which_input, uint64_t rel_start, uint64_t rel_end, const pmt::pmt_t &key)
 Operates like gr::block::get_tags_in_window with the ability to only return tags with the specified key. More...
 
void enable_update_rate (bool en)
 
buffer_sptr allocate_buffer (size_t port, int downstream_max_nitems, uint64_t downstream_lcm_nitems, uint32_t downstream_max_out_mult)
 Allocate a buffer for the given output port of this block. Note that the downstream max number of items must be passed in to this function for consideration. More...
 
- Protected Member Functions inherited from gr::basic_block
 basic_block (void)
 
 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. More...
 
void set_input_signature (gr::io_signature::sptr iosig)
 may only be called during constructor More...
 
void set_output_signature (gr::io_signature::sptr iosig)
 may only be called during constructor More...
 
void set_color (vcolor color)
 Allow the flowgraph to set for sorting and partitioning. More...
 
vcolor color () const
 
virtual bool has_msg_handler (pmt::pmt_t which_port)
 Tests if there is a handler attached to port which_port. More...
 
virtual void dispatch_msg (pmt::pmt_t which_port, pmt::pmt_t msg)
 
template<typename Derived >
std::shared_ptr< Derived > shared_from_base ()
 This is meant to be called by derived classes (e.g. block) to get a shared pointer internally. This is needed because std::enable_shared_from_this doesn't seem to work with derived classes in an inheritance hierarchy. More...
 
- Protected Attributes inherited from gr::block
std::vector< long > d_max_output_buffer
 
std::vector< long > d_min_output_buffer
 
unsigned int d_blkd_input_timer_value = 250
 
gr::thread::mutex d_setlock
 
const pmt::pmt_t d_pmt_done
 
const pmt::pmt_t d_system_port
 
- Protected Attributes inherited from gr::basic_block
std::string d_name
 
gr::io_signature::sptr d_input_signature
 
gr::io_signature::sptr d_output_signature
 
long d_unique_id
 
long d_symbolic_id
 
std::string d_symbol_name
 
std::string d_symbol_alias
 
vcolor d_color
 
bool d_rpc_set
 
gr::logger_ptr d_logger
 
gr::logger_ptr d_debug_logger
 Default logger. More...
 
msg_queue_map_t msg_queue
 Verbose logger. More...
 
std::vector< rpcbasic_sptr > d_rpc_vars
 
pmt::pmt_t d_message_subscribers
 

Detailed Description

Decision Feedback Equalizer.

Member Typedef Documentation

◆ sptr

Member Function Documentation

◆ equalize()

virtual int gr::digital::decision_feedback_equalizer::equalize ( const gr_complex input_samples,
gr_complex output_symbols,
unsigned int  num_inputs,
unsigned int  max_num_outputs,
std::vector< unsigned int >  training_start_samples = std::vector< unsigned int >(0),
bool  history_included = false,
gr_complex taps = nullptr,
unsigned short *  state = nullptr 
)
pure virtual

Public "work" function - equalize a block of input samples.

Behaves similar to the block's work function, but made public to be able to be called outside the GNU Radio scheduler on bursty data

Parameters
input_samplesBuffer of input samples to equalize
output_symbolsBuffer of output symbols post equalization
num_inputsNumber of input samples provided
max_num_outputsSize of output_symbols buffer to write into
training_start_samplesVector of starting positions of training sequences within the input_samples buffer
history_includedFlag to indicate whether history has been provided at the beginning of the input_samples buffer, as would normally be provided in a work() call. The work() function of this block sets this to true, but in bursty operation, this should be set to false
tapsOptional output vector buffer of tap weights calculated at each sample of the output
stateOptional output state of the equalizer for debug {IDLE, TRAINING, DD}

◆ make()

static sptr gr::digital::decision_feedback_equalizer::make ( unsigned  num_taps_forward,
unsigned  num_taps_feedback,
unsigned  sps,
adaptive_algorithm_sptr  alg,
bool  adapt_after_training = true,
std::vector< gr_complex training_sequence = std::vector< gr_complex >(),
const std::string &  training_start_tag = "" 
)
static

Return a shared_ptr to a new instance of gr::digital::decision_feedback_equalizer.

The Decision Feedback Equalizer block equalizes the incoming signal using an FIR filter representing both the forward and feedback taps

If provided with a training sequence and a training start tag, data aided equalization will be performed starting with the tagged sample. If training-based equalization is active and the training sequence ends, then optionally decision directed equalization will be performed given the adapt_after_training If no training sequence or no tag is provided, decision directed equalization will be performed This equalizer decimates to the symbol rate according to the samples per symbol param

Parameters
num_taps_forwardNumber of feedforward taps for the FIR filter
num_taps_feedbackNumber of feedback taps for the FIR filter
spsint - Samples per Symbol
algAdaptive algorithm object
training_sequenceSequence of samples that will be used to train the equalizer. Provide empty vector to default to DD equalizer
adapt_after_trainingbool - set true to continue DD training after training sequence has been used up
training_start_tagstring - tag that indicates the start of the training sequence in the incoming data

◆ set_taps()

virtual void gr::digital::decision_feedback_equalizer::set_taps ( const std::vector< gr_complex > &  taps)
pure virtual

◆ taps()

virtual std::vector<gr_complex> gr::digital::decision_feedback_equalizer::taps ( ) const
pure virtual

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