GNU Radio 3.6.5.1 C++ API
digital_ofdm_cyclic_prefixer Class Reference

Adds a cyclic prefix and performs pulse shaping on OFDM symbols.Input: OFDM symbols (in the time domain, i.e. after the IFFT). Optionally, entire frames can be processed. In this case, len_tag_key must be specified which holds the key of the tag that denotes how many OFDM symbols are in a frame. Output: A stream of (scalar) complex symbols, which include the cyclic prefix and the pulse shaping. Note: If complete frames are processed, and rolloff_len is greater than zero, the final OFDM symbol is followed by the delay line of the pulse shaping. More...

#include <digital_ofdm_cyclic_prefixer.h>

Inheritance diagram for digital_ofdm_cyclic_prefixer:
gr_tagged_stream_block gr_block gr_basic_block gr_msg_accepter gruel::msg_accepter

Public Member Functions

int work (int noutput_items, gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
 Just like gr_block::general_work, but makes sure the input is valid.
- Public Member Functions inherited from gr_tagged_stream_block
void forecast (int noutput_items, gr_vector_int &ninput_items_required)
 Don't override this.
int general_work (int noutput_items, gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)
- 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.
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
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.
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.
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 min_noutput_items () const
 Return the minimum number of output items this block can produce during a call to work.
void set_min_noutput_items (int m)
 Set the minimum number of output items this block can produce during a call to work.
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 output items this 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.
float pc_noutput_items ()
 Gets average noutput_items performance counter.
float pc_noutput_items_var ()
 Gets variance of noutput_items performance counter.
float pc_nproduced ()
 Gets average num items produced performance counter.
float pc_nproduced_var ()
 Gets variance of num items produced performance counter.
float pc_input_buffers_full (int which)
 Gets average fullness of which input buffer.
float pc_input_buffers_full_var (int which)
 Gets variance of fullness of which input buffer.
std::vector< float > pc_input_buffers_full ()
 Gets average fullness of all input buffers.
std::vector< float > pc_input_buffers_full_var ()
 Gets variance of fullness of all input buffers.
float pc_output_buffers_full (int which)
 Gets average fullness of which input buffer.
float pc_output_buffers_full_var (int which)
 Gets variance of fullness of which input buffer.
std::vector< float > pc_output_buffers_full ()
 Gets average fullness of all output buffers.
std::vector< float > pc_output_buffers_full_var ()
 Gets variance of fullness of all output buffers.
float pc_work_time ()
 Gets average clock cycles spent in work.
float pc_work_time_var ()
 Gets average clock cycles spent in work.
void reset_perf_counters ()
 Resets the performance counters.
void set_processor_affinity (const std::vector< int > &mask)
 Set the thread's affinity to processor core n.
void unset_processor_affinity ()
 Remove processor affinity to a specific core.
std::vector< int > processor_affinity ()
 Get the current processor affinity.
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.
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 ()
size_t nmsgs (pmt::pmt_t which_port)
 How many messages in the queue?
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.
- 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
- Public Member Functions inherited from gruel::msg_accepter
 msg_accepter ()
virtual ~msg_accepter ()

Protected Member Functions

 digital_ofdm_cyclic_prefixer (size_t input_size, size_t output_size, int rolloff_len, const std::string &len_tag_key)
int calculate_output_stream_length (const gr_vector_int &ninput_items)
 Return the number of complex samples from the number of OFDM symbols (includes rolloff)
- Protected Member Functions inherited from gr_tagged_stream_block
 gr_tagged_stream_block (void)
 gr_tagged_stream_block (const std::string &name, gr_io_signature_sptr input_signature, gr_io_signature_sptr output_signature, const std::string &length_tag_key)
virtual void parse_length_tags (const std::vector< std::vector< gr_tag_t > > &tags, gr_vector_int &n_input_items_reqd)
 Parse all tags on the first sample of a PDU, return the number of items per input and prune the length tags.
virtual void update_length_tags (int n_produced, int n_ports)
 Set the new length tags on the output stream.
- 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.
void add_item_tag (unsigned int which_output, const gr_tag_t &tag)
 Adds a new tag onto the given output buffer.
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.
void remove_item_tag (unsigned int which_input, const gr_tag_t &tag)
 Removes a tag from the given input 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.
- Protected Member Functions inherited from gr_basic_block
 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
bool has_msg_handler (pmt::pmt_t which_port)
 Tests if there is a handler attached to port which_port.
virtual void dispatch_msg (pmt::pmt_t which_port, pmt::pmt_t msg)

Friends

DIGITAL_API
digital_ofdm_cyclic_prefixer_sptr 
digital_make_ofdm_cyclic_prefixer (size_t input_size, size_t output_size, int rolloff_len, const std::string &len_tag_key)

Additional Inherited Members

- 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 }
- Protected Types inherited from gr_basic_block
enum  vcolor { WHITE, GREY, BLACK }
- Protected Attributes inherited from gr_tagged_stream_block
std::string d_length_tag_key_str

Detailed Description

Adds a cyclic prefix and performs pulse shaping on OFDM symbols.

Input: OFDM symbols (in the time domain, i.e. after the IFFT). Optionally, entire frames can be processed. In this case, len_tag_key must be specified which holds the key of the tag that denotes how many OFDM symbols are in a frame. Output: A stream of (scalar) complex symbols, which include the cyclic prefix and the pulse shaping. Note: If complete frames are processed, and rolloff_len is greater than zero, the final OFDM symbol is followed by the delay line of the pulse shaping.

The pulse shape is a raised cosine in the time domain.

Constructor & Destructor Documentation

digital_ofdm_cyclic_prefixer::digital_ofdm_cyclic_prefixer ( size_t  input_size,
size_t  output_size,
int  rolloff_len,
const std::string &  len_tag_key 
)
protected

Member Function Documentation

int digital_ofdm_cyclic_prefixer::calculate_output_stream_length ( const gr_vector_int ninput_items)
protectedvirtual

Return the number of complex samples from the number of OFDM symbols (includes rolloff)

Reimplemented from gr_tagged_stream_block.

int digital_ofdm_cyclic_prefixer::work ( int  noutput_items,
gr_vector_int ninput_items,
gr_vector_const_void_star input_items,
gr_vector_void_star output_items 
)
virtual

Just like gr_block::general_work, but makes sure the input is valid.

The user must override work to define the signal processing code. Check the documentation for general_work() to see what happens here.

Like gr_sync_block, this calls consume() for you (it consumes ninput_items[i] items from the i-th port).

A note on tag propagation: The PDU length tags are handled by other functions, but all other tags are handled just as in any other gr_block. So, most likely, you either set the tag propagation policy to TPP_DONT and handle the tag propagation manually, or you propagate tags through the scheduler and don't do anything here.

Parameters
noutput_itemsThe size of the writable output buffer
ninput_itemsThe exact size of the items on every input for this particular PDU. These will be consumed if a length tag key is provided!
input_itemsSee gr_block
output_itemsSee gr_block

Implements gr_tagged_stream_block.

Friends And Related Function Documentation

DIGITAL_API digital_ofdm_cyclic_prefixer_sptr digital_make_ofdm_cyclic_prefixer ( size_t  input_size,
size_t  output_size,
int  rolloff_len,
const std::string &  len_tag_key 
)
friend
Parameters
input_sizeFFT length (i.e. length of the OFDM symbols)
output_sizeFFT length + cyclic prefix length (in samples)
rolloff_lenLength of the rolloff flank in samples
len_tag_keyFor framed processing the key of the length tag

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