GNU Radio 3.6.5.1 C++ API
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Schmidl & Cox synchronisation for OFDM. More...
#include <digital_ofdm_sync_sc_cfb.h>
Public Member Functions | |
~digital_ofdm_sync_sc_cfb () | |
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virtual | ~gr_hier_block2 () |
opaque_self | self () |
Return an object, representing the current block, which can be passed to connect. | |
void | connect (gr_basic_block_sptr block) |
Add a stand-alone (possibly hierarchical) block to internal graph. | |
void | connect (gr_basic_block_sptr src, int src_port, gr_basic_block_sptr dst, int dst_port) |
Add gr-blocks or hierarchical blocks to internal graph and wire together. | |
void | msg_connect (gr_basic_block_sptr src, pmt::pmt_t srcport, gr_basic_block_sptr dst, pmt::pmt_t dstport) |
Add gr-blocks or hierarchical blocks to internal graph and wire together. | |
void | msg_connect (gr_basic_block_sptr src, std::string srcport, gr_basic_block_sptr dst, std::string dstport) |
void | msg_disconnect (gr_basic_block_sptr src, pmt::pmt_t srcport, gr_basic_block_sptr dst, pmt::pmt_t dstport) |
void | msg_disconnect (gr_basic_block_sptr src, std::string srcport, gr_basic_block_sptr dst, std::string dstport) |
void | disconnect (gr_basic_block_sptr block) |
Remove a gr-block or hierarchical block from the internal flowgraph. | |
void | disconnect (gr_basic_block_sptr src, int src_port, gr_basic_block_sptr dst, int dst_port) |
Disconnect a pair of gr-blocks or hierarchical blocks in internal flowgraph. | |
void | disconnect_all () |
Disconnect all connections in the internal flowgraph. | |
virtual void | lock () |
virtual void | unlock () |
gr_flat_flowgraph_sptr | flatten () const |
gr_hier_block2_sptr | to_hier_block2 () |
bool | has_msg_port (pmt::pmt_t which_port) |
bool | message_port_is_hier (pmt::pmt_t port_id) |
bool | message_port_is_hier_in (pmt::pmt_t port_id) |
bool | message_port_is_hier_out (pmt::pmt_t port_id) |
void | message_port_register_hier_in (pmt::pmt_t port_id) |
void | message_port_register_hier_out (pmt::pmt_t port_id) |
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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) |
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 | 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. | |
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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 | |
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msg_accepter () | |
virtual | ~msg_accepter () |
Friends | |
DIGITAL_API digital_ofdm_sync_sc_cfb_sptr | digital_make_ofdm_sync_sc_cfb (int fft_len, int cp_len, bool use_even_carriers) |
Additional Inherited Members | |
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typedef gr_basic_block_sptr | opaque_self |
typedef for object returned from self(). | |
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pmt::pmt_t | hier_message_ports_in |
pmt::pmt_t | hier_message_ports_out |
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enum | vcolor { WHITE, GREY, BLACK } |
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gr_hier_block2 (void) | |
gr_hier_block2 (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 |
long | d_symbolic_id |
std::string | d_symbol_name |
std::string | d_symbol_alias |
vcolor | d_color |
msg_queue_map_t | msg_queue |
pmt::pmt_t | message_subscribers |
Schmidl & Cox synchronisation for OFDM.
Input: complex samples. Output 0: Fine frequency offset, scaled by the OFDM symbol duration. This is in [1]. The normalized frequency offset is then 2.0*output0/fft_len. Output 1: Beginning of the first OFDM symbol after the first (doubled) OFDM symbol. The beginning is marked with a 1 (it's 0 everywhere else).
The evaluation of the coarse frequency offset is not done in this block. Also, the initial equalizer taps are not calculated here.
Note that we use a different normalization factor in the timing metric than the authors do in their original work[1]. If the timing metric (8) is
we calculate the normalization as
i.e., we estimate the energy from both half-symbols. This avoids spurious detects at the end of a burst, when the energy level suddenly drops.
[1] Schmidl, T.M. and Cox, D.C., "Robust frequency and timing synchronization for OFDM", Communications, IEEE Transactions on, 1997.
digital_ofdm_sync_sc_cfb::~digital_ofdm_sync_sc_cfb | ( | ) |
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friend |
fft_len | FFT length |
cp_len | Length of the guard interval (cyclic prefix) in samples |
use_even_carriers | If true, the carriers in the sync preamble are occupied such that the even carriers are used (0, 2, 4, ...). If you use all carriers, that would include the DC carrier, so be careful. |