take a vector of complex constellation points in from an FFT and performs a correlation and equalization.This block takes the output of an FFT of a received OFDM symbol and finds the start of a frame based on two known symbols. It also looks at the surrounding bins in the FFT output for the correlation in case there is a large frequency shift in the data. This block assumes that the fine frequency shift has already been corrected and that the samples fall in the middle of one FFT bin.
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Public Member Functions |
float | snr () |
| Return an estimate of the SNR of the channel.
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| ~digital_ofdm_frame_acquisition (void) |
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
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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.
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virtual bool | start () |
| Called to enable drivers, etc for i/o devices.
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virtual bool | stop () |
| Called to disable drivers, etc for i/o devices.
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void | set_output_multiple (int multiple) |
| Constrain the noutput_items argument passed to forecast and general_work.
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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)
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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.
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void | consume_each (int how_many_items) |
| Tell the scheduler how_many_items were consumed on each input stream.
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void | produce (int which_output, int how_many_items) |
| Tell the scheduler how_many_items were produced on output stream which_output .
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void | set_relative_rate (double relative_rate) |
| Set the approximate output rate / input rate.
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double | relative_rate () const |
| return the approximate output rate / input rate
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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.
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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.
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uint64_t | nitems_read (unsigned int which_input) |
| Return the number of items read on input stream which_input.
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uint64_t | nitems_written (unsigned int which_output) |
| Return the number of items written on output stream which_output.
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tag_propagation_policy_t | tag_propagation_policy () |
| Asks for the policy used by the scheduler to moved tags downstream.
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void | set_tag_propagation_policy (tag_propagation_policy_t p) |
| Set the policy by the scheduler to determine how tags are moved downstream.
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gr_block_detail_sptr | detail () const |
void | set_detail (gr_block_detail_sptr detail) |
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.
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template<typename T > |
void | set_msg_handler (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 msg) |
| send msg to msg_accepter
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| msg_accepter () |
virtual | ~msg_accepter () |
Protected Member Functions |
| digital_ofdm_frame_acquisition (unsigned int occupied_carriers, unsigned int fft_length, unsigned int cplen, const std::vector< gr_complex > &known_symbol, unsigned int max_fft_shift_len) |
| 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.
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void | add_item_tag (unsigned int which_output, const gr_tag_t &tag) |
| Adds a new tag onto the given output buffer.
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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.
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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.
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| 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.
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void | set_input_signature (gr_io_signature_sptr iosig) |
| may only be called during constructor
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void | set_output_signature (gr_io_signature_sptr iosig) |
| may only be called during constructor
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void | set_color (vcolor color) |
| Allow the flowgraph to set for sorting and partitioning.
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vcolor | color () const |
take a vector of complex constellation points in from an FFT and performs a correlation and equalization.
This block takes the output of an FFT of a received OFDM symbol and finds the start of a frame based on two known symbols. It also looks at the surrounding bins in the FFT output for the correlation in case there is a large frequency shift in the data. This block assumes that the fine frequency shift has already been corrected and that the samples fall in the middle of one FFT bin.
It then uses one of those known symbols to estimate the channel response over all subcarriers and does a simple 1-tap equalization on all subcarriers. This corrects for the phase and amplitude distortion caused by the channel.