GNU Radio 3.7.2git-47-g5cfb1151 C++ API
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Schmidl & Cox synchronisation for OFDM. More...
#include <ofdm_sync_sc_cfb.h>
Public Types | |
typedef boost::shared_ptr < ofdm_sync_sc_cfb > | sptr |
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typedef basic_block_sptr | opaque_self |
typedef for object returned from self(). More... | |
Static Public Member Functions | |
static sptr | make (int fft_len, int cp_len, bool use_even_carriers=false) |
Additional Inherited Members | |
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virtual | ~hier_block2 () |
opaque_self | self () |
Return an object, representing the current block, which can be passed to connect. More... | |
void | connect (basic_block_sptr block) |
Add a stand-alone (possibly hierarchical) block to internal graph. More... | |
void | connect (basic_block_sptr src, int src_port, basic_block_sptr dst, int dst_port) |
Add gr-blocks or hierarchical blocks to internal graph and wire together. More... | |
void | msg_connect (basic_block_sptr src, pmt::pmt_t srcport, basic_block_sptr dst, pmt::pmt_t dstport) |
Add gr-blocks or hierarchical blocks to internal graph and wire together. More... | |
void | msg_connect (basic_block_sptr src, std::string srcport, basic_block_sptr dst, std::string dstport) |
void | msg_disconnect (basic_block_sptr src, pmt::pmt_t srcport, basic_block_sptr dst, pmt::pmt_t dstport) |
void | msg_disconnect (basic_block_sptr src, std::string srcport, basic_block_sptr dst, std::string dstport) |
void | disconnect (basic_block_sptr block) |
Remove a gr-block or hierarchical block from the internal flowgraph. More... | |
void | disconnect (basic_block_sptr src, int src_port, basic_block_sptr dst, int dst_port) |
Disconnect a pair of gr-blocks or hierarchical blocks in internal flowgraph. More... | |
void | disconnect_all () |
Disconnect all connections in the internal flowgraph. More... | |
virtual void | lock () |
virtual void | unlock () |
flat_flowgraph_sptr | flatten () const |
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) |
void | set_processor_affinity (const std::vector< int > &mask) |
Set the affinity of all blocks in hier_block2 to processor core n . More... | |
void | unset_processor_affinity () |
Remove processor affinity for all blocks in hier_block2. More... | |
std::vector< int > | processor_affinity () |
Get the current processor affinity. More... | |
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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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hier_block2 (void) | |
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 |
bool | d_rpc_set |
msg_queue_map_t | msg_queue |
std::vector< boost::any > | d_rpc_vars |
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.
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static |
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. |