Struct dp_burst_demod_state_t¶

ClassList > dp_burst_demod_state_t

BurstDemod state. Allocate with dp_burst_demod_create_desc() .

• #include <burst_demod_core.h>

Public Attributes¶

Public Attributes Documentation¶

variable acq_code¶

uint8_t* dp_burst_demod_state_t::acq_code;

owned acq preamble code (0/1), length acq_sf.

variable acq_reps¶

size_t dp_burst_demod_state_t::acq_reps;

acq preamble repetitions.

variable acq_sf¶

size_t dp_burst_demod_state_t::acq_sf;

acq code length (chips).

variable carrier_hz¶

double dp_burst_demod_state_t::carrier_hz;

RF carrier (Hz) for code-Doppler; 0 = ignore.

variable chip_rate¶

double dp_burst_demod_state_t::chip_rate;

chip rate (Hz).

variable data_code¶

uint8_t* dp_burst_demod_state_t::data_code;

owned data spreading code (0/1), length data_sf.

variable data_sf¶

size_t dp_burst_demod_state_t::data_sf;

data spreading factor (chips/symbol).

variable est_cn0_dbhz¶

double dp_burst_demod_state_t::est_cn0_dbhz;

Carrier-to-noise DENSITY, dB-Hz, referred to the CHANNEL: the realized symbol estimate 1/est_n0 lifted by the symbol rate and corrected for the despreading loss that est_timing_chips measures. Sample-rate invariant, so it survives a front-end rate change, and it does not move when the receiver's own timing is off by a fraction of a chip which a realized SNR does, by 4.8 dB at half a chip. Zero until a demod() produces a frame. DEGRADED BY RESIDUAL PHASE, by construction: est_n0 reads the noise off the quadrature, and a rotation puts signal there, so an untracked Doppler rate reads as a worse link 101 dB worse on a noiseless input. The realized link IS worse, so the number is not wrong; it simply cannot say WHICH of the two happened. dp_burst_demod_symbols() can, because only Q against I separates them (doppler#1087). See doppler#1304.

variable est_freq_hz¶

double dp_burst_demod_state_t::est_freq_hz;

estimated residual Doppler (Hz).

variable est_n0¶

double dp_burst_demod_state_t::est_n0;

Noise power the LLRs are scaled by, referred to unit symbol amplitude. Published so a caller can undo the scaling, or compare bursts by it.

variable est_rate_hz¶

double dp_burst_demod_state_t::est_rate_hz;

estimated Doppler rate (Hz/s).

variable est_segments¶

size_t dp_burst_demod_state_t::est_segments;

partials per acq period for the estimate.

variable est_timing_chips¶

double dp_burst_demod_state_t::est_timing_chips;

Burst-start error the demodulator MEASURED, in chips, signed, relative to the start given to set_prior(). The whole-SAMPLE part of it was removed before despreading; only the fraction of a sample that a shift cannot remove is still a loss, and only that fraction is taken out of est_cn0_dbhz. The symbols keep the loss either way. Acquisition resolves a start to one SAMPLE, so a residual here is structural rather than a caller's error. BOUNDED at half a chip, which is the metric's limit and not a budget: a whole-chip slip re-aligns every partial against its neighbour's chip and reads as no slip at all. A magnitude AT that bound therefore means the search saturated the start is further out than this object can measure, and est_cn0_dbhz is then a floor rather than a measurement. Fixing that is acquisition's, which is what resolves a start.

variable f0_prior¶

double dp_burst_demod_state_t::f0_prior;

coarse Doppler prior (cycles/sample).

variable frame_offset¶

size_t dp_burst_demod_state_t::frame_offset;

symbol offset of the sync word.

variable frame_syms¶

size_t dp_burst_demod_state_t::frame_syms;

symbols the frame occupies, sync word included — the description's layout length, read at create. What they MEAN is the frame description's business, one layer up.

variable llr¶

float* dp_burst_demod_state_t::llr;

The frame's soft bits, mpsk_soft_demap's convention: positive means bit 0, so L < 0 is the hard decision demod() returned. Valid until the next demod(); n_llr of them.

variable max_rate¶

double dp_burst_demod_state_t::max_rate;

chirp-rate search half-span (cycles/sample^2).

variable n_llr¶

size_t dp_burst_demod_state_t::n_llr;

LLRs the last demod() wrote (the frame's length).

variable n_part¶

size_t dp_burst_demod_state_t::n_part;

variable n_sym¶

size_t dp_burst_demod_state_t::n_sym;

Symbols the last demod() wrote (the frame's length).

variable n_symbols¶

size_t dp_burst_demod_state_t::n_symbols;

despread data symbols produced.

variable part¶

float _Complex* dp_burst_demod_state_t::part;

preamble partials scratch (acq_reps*est_seg).

variable ppe¶

dp_ppe_state_t* dp_burst_demod_state_t::ppe;

feedforward (rate x freq) estimator.

variable spc¶

size_t dp_burst_demod_state_t::spc;

samples per chip.

variable start¶

size_t dp_burst_demod_state_t::start;

preamble start sample in the burst.

variable sym¶

float _Complex* dp_burst_demod_state_t::sym;

The frame's DEROTATED, unit-normalised complex symbols the constellation the LLRs are the real part of. Built either way to compute the projection and the noise estimate, and freed unread until doppler#1087: for BPSK a residual phase error and a genuine amplitude loss are indistinguishable in every real-only statistic (a rotation scales Re by cos(phi) without adding noise), so |LLR|, its spread and the BER all agree while only the quadrature separates them. Valid until the next demod(); n_sym of them.

variable sync¶

int8_t* dp_burst_demod_state_t::sync;

owned sync word as +/-1, length sync_len — the correlation template, and the only thing this object knows about the frame's CONTENT.

variable sync_len¶

size_t dp_burst_demod_state_t::sync_len;

sync word length (symbols).

The documentation for this class was generated from the following file native/inc/doppler/burst_demod/burst_demod_core.h