GNU Radio 3.6.4.1 C++ API
gr::filter::pfb_arb_resampler_fff Class Referenceabstract

Polyphase filterbank arbitrary resampler with float input, float output and float taps. More...

#include <pfb_arb_resampler_fff.h>

Inheritance diagram for gr::filter::pfb_arb_resampler_fff:
gr_block gr_basic_block gr_msg_accepter gruel::msg_accepter gr::filter::pfb_arb_resampler_fff_impl

Public Types

typedef boost::shared_ptr
< pfb_arb_resampler_fff
sptr
 
- 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 }
 

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
 
virtual void set_rate (float rate)=0
 
virtual void set_phase (float ph)=0
 
virtual float phase () const =0
 
- Public Member Functions inherited from gr_block
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 void forecast (int noutput_items, gr_vector_int &ninput_items_required)
 Estimate input requirements given output request. More...
 
virtual 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...
 
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...
 
double relative_rate () const
 return the approximate output rate / input rate More...
 
virtual 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...
 
virtual 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...
 
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)
 Sets max buffer size on all output ports. More...
 
void set_max_output_buffer (int port, long max_output_buffer)
 Sets 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)
 Sets min buffer size on all output ports. More...
 
void set_min_output_buffer (int port, long min_output_buffer)
 Sets min buffer size on output port port. More...
 
float pc_noutput_items ()
 Gets average noutput_items performance counter. More...
 
float pc_noutput_items_var ()
 Gets variance of noutput_items performance counter. More...
 
float pc_nproduced ()
 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 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 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 average fullness of which input buffer. More...
 
float pc_output_buffers_full_var (int which)
 Gets variance of fullness of which input buffer. More...
 
std::vector< float > pc_output_buffers_full ()
 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 average clock cycles spent in work. More...
 
float pc_work_time_var ()
 Gets average clock cycles spent in work. More...
 
void reset_perf_counters ()
 Resets the performance counters. More...
 
void set_processor_affinity (const std::vector< unsigned int > &mask)
 Set the thread's affinity to processor core n. More...
 
void unset_processor_affinity ()
 Remove processor affinity to a specific core. More...
 
std::vector< unsigned int > processor_affinity ()
 Get the current processor affinity. More...
 
gr_block_detail_sptr detail () const
 
void set_detail (gr_block_detail_sptr detail)
 
- Public Member Functions inherited from gr_basic_block
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. 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 ()
 
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)
 
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. 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
 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 More...
 
- Public Member Functions inherited from gruel::msg_accepter
 msg_accepter ()
 
virtual ~msg_accepter ()
 

Static Public Member Functions

static sptr make (float rate, const std::vector< float > &taps, unsigned int filter_size=32)
 

Additional Inherited Members

- Protected Types inherited from gr_basic_block
enum  vcolor { WHITE, GREY, BLACK }
 
- Protected Member Functions inherited from gr_block
 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. More...
 
void add_item_tag (unsigned int which_output, const gr_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)
 Removes a tag from the given input buffer. More...
 
void remove_item_tag (unsigned int which_input, const gr_tag_t &tag)
 Removes a tag from the given input buffer. More...
 
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. More...
 
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. More...
 
- 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 arbitrary resampler with float input, float output and float taps.

This block takes in a signal stream and performs arbitrary resampling. The resampling rate can be any real number r. The resampling is done by constructing N filters where N is the interpolation rate. We then calculate D where D = floor(N/r).

Using N and D, we can perform rational resampling where N/D is a rational number close to the input rate r where we have N filters and we cycle through them as a polyphase filterbank with a stride of D so that i+1 = (i + D) % N.

To get the arbitrary rate, we want to interpolate between two points. For each value out, we take an output from the current filter, i, and the next filter i+1 and then linearly interpolate between the two based on the real resampling rate we want.

The linear interpolation only provides us with an approximation to the real sampling rate specified. The error is a quantization error between the two filters we used as our interpolation points. To this end, the number of filters, N, used determines the quantization error; the larger N, the smaller the noise. You can design for a specified noise floor by setting the filter size (parameters filter_size). The size defaults to 32 filters, which is about as good as most implementations need.

The trick with designing this filter is in how to specify the taps of the prototype filter. Like the PFB interpolator, the taps are specified using the interpolated filter rate. In this case, that rate is the input sample rate multiplied by the number of filters in the filterbank, which is also the interpolation rate. All other values should be relative to this rate.

For example, for a 32-filter arbitrary resampler and using the GNU Radio's firdes utility to build the filter, 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 the interpolation rate (32).

self._taps = filter.firdes.low_pass_2(32, 32*fs, BW, TB, attenuation_dB=ATT, window=filter.firdes.WIN_BLACKMAN_hARRIS)

The theory behind this block can be found in Chapter 7.5 of the following book.

f. harris, "Multirate Signal Processing for Communication Systems", Upper Saddle River, NJ: Prentice Hall, Inc. 2004.

Member Typedef Documentation

Member Function Documentation

static sptr gr::filter::pfb_arb_resampler_fff::make ( float  rate,
const std::vector< float > &  taps,
unsigned int  filter_size = 32 
)
static

Build the polyphase filterbank arbitray resampler.

Parameters
rate(float) Specifies the resampling rate to use
taps(vector/list of floats) The prototype filter to populate the filterbank. The taps should be generated at the filter_size sampling rate.
filter_size(unsigned int) The number of filters in the filter bank. This is directly related to quantization noise introduced during the resampling. Defaults to 32 filters.
virtual float gr::filter::pfb_arb_resampler_fff::phase ( ) const
pure virtual

Gets the current phase of the resampler in radians (2 to 2pi).

Implemented in gr::filter::pfb_arb_resampler_fff_impl.

virtual void gr::filter::pfb_arb_resampler_fff::print_taps ( )
pure virtual

Print all of the filterbank taps to screen.

Implemented in gr::filter::pfb_arb_resampler_fff_impl.

virtual void gr::filter::pfb_arb_resampler_fff::set_phase ( float  ph)
pure virtual

Sets the current phase offset in radians (0 to 2pi).

Implemented in gr::filter::pfb_arb_resampler_fff_impl.

virtual void gr::filter::pfb_arb_resampler_fff::set_rate ( float  rate)
pure virtual

Sets the resampling rate of the block.

Implemented in gr::filter::pfb_arb_resampler_fff_impl.

virtual void gr::filter::pfb_arb_resampler_fff::set_taps ( const std::vector< float > &  taps)
pure virtual

Resets the filterbank's filter taps with the new prototype filter

Parameters
taps(vector/list of floats) The prototype filter to populate the filterbank.

Implemented in gr::filter::pfb_arb_resampler_fff_impl.

virtual std::vector<std::vector<float> > gr::filter::pfb_arb_resampler_fff::taps ( ) const
pure virtual

Return a vector<vector<>> of the filterbank taps

Implemented in gr::filter::pfb_arb_resampler_fff_impl.


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