56 lines
1.7 KiB
C++
56 lines
1.7 KiB
C++
#pragma once
|
|
|
|
#include <stdint.h>
|
|
#include <complex>
|
|
|
|
namespace ft8 {
|
|
|
|
struct MagArray {
|
|
int num_blocks; // number of total blocks (symbols)
|
|
int num_bins; // number of FFT bins
|
|
int time_osr; // number of time subdivisions
|
|
int freq_osr; // number of frequency subdivisions
|
|
uint8_t * mag; // FFT magnitudes as [blocks][time_sub][freq_sub][num_bins]
|
|
};
|
|
|
|
struct Candidate {
|
|
int16_t score;
|
|
int16_t time_offset;
|
|
int16_t freq_offset;
|
|
uint8_t time_sub;
|
|
uint8_t freq_sub;
|
|
};
|
|
|
|
class Monitor1Base {
|
|
public:
|
|
Monitor1Base(float sample_rate, int time_osr = 2, int freq_osr = 2, float fmin = 300, float fmax = 3000);
|
|
|
|
void feed(const float *frame);
|
|
void search();
|
|
void reset();
|
|
protected:
|
|
float *window_fn; // [nfft]
|
|
float *fft_frame; // [nfft]
|
|
float *last_frame; // [nfft * 3/4]
|
|
std::complex<float> *freqdata; // [nfft/2 + 1]
|
|
int nfft;
|
|
|
|
int offset;
|
|
int time_sub;
|
|
ft8::MagArray power;
|
|
|
|
// [N] real --> [N/2 + 1] log magnitudes (decibels)
|
|
// virtual void fft_forward_mag_db(const float *frame, uint8_t *mag_db) = 0;
|
|
virtual void fft_forward(const float *in, std::complex<float> *out) = 0;
|
|
};
|
|
|
|
// Localize top N candidates in frequency and time according to their sync strength (looking at Costas symbols)
|
|
// We treat and organize the candidate list as a min-heap (empty initially).
|
|
int find_sync(const MagArray * power, const uint8_t *sync_map, int num_candidates, Candidate *heap, int min_score = 0);
|
|
|
|
|
|
// Compute log likelihood log(p(1) / p(0)) of 174 message bits
|
|
// for later use in soft-decision LDPC decoding
|
|
void extract_likelihood(const MagArray *power, const Candidate & cand, const uint8_t *code_map, float *log174);
|
|
|
|
}
|