kopia lustrzana https://github.com/N0BOY/FT8CN
293 wiersze
12 KiB
C
293 wiersze
12 KiB
C
//
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// Created by jmsmf on 2022/4/24.
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//
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#include "ft8Decoder.h"
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#define LOG_LEVEL LOG_INFO
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//decoder_t decoder;
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// Hanning窗（汉宁窗）适用于95%的情况。
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static float hann_i(int i, int N) {
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float x = sinf((float) M_PI * i / N);
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return x * x;
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}
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//把信号FFT,在解码decoder中减去信号
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void signalToFFT(decoder_t *decoder, float signal[], int sample_rate) {
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int nfft = kFreq_osr * (int) (sample_rate * FT8_SYMBOL_PERIOD);//nfft=一个FSK符号的样本数*频率过采样率
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float fft_norm = 2.0f / nfft;//< FFT归一化因子。FFT normalization factor
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float *window = (float *) malloc(
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nfft * sizeof(window[0]));// 申请窗空间，大小是fft块大小*sizeof(me->windows[0])
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for (int i = 0; i < nfft; ++i) {
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window[i] = hann_i(i, nfft);// 使用Hanning窗
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// window[i] = blackman_i(i, me->nfft);// Blackman-Harris窗
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// window[i] = hamming_i(i, me->nfft);// Hamming窗
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// window[i] = (i < len_window) ? hann_i(i, len_window) : 0;
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}
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// 申请当前STFT(短时傅氏变换)分析框架（nfft样本）的空间。
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//last_frame:申请傅里叶变换分析框架用的（nfft样本）。
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// 空间大小=时域数据量*数据类型占用的空间=一个FSK符号占用的采样数据量*频率过采样率=12000*0.16*2*SizeOf(float)
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float *last_frame = (float *) malloc(nfft * sizeof(last_frame[0]));
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size_t fft_work_size;
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// 第一步，获取可以用的FFT工作区域的大小到fft_work_size
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//nfft=一个FSK符号的样本数*频率过采样率=0.16*12000*2=3840
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kiss_fftr_alloc(nfft, 0, 0, &fft_work_size);
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// 申请FFT工作区域的内存，38676个
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void *fft_work = malloc(fft_work_size);
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//第二步，返回fft的设置信息
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kiss_fftr_cfg fft_cfg = kiss_fftr_alloc(nfft, 0, fft_work, &fft_work_size);
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free(fft_work);
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free(window);
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free(last_frame);
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}
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void *init_decoder(int64_t utcTime, int sample_rate, int num_samples, bool is_ft8) {
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//此处，改为一个变量，不是以指针，申请新内存的方式处理了。
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//其实这种方式要注意一个问题，在一个周期之内，必须解码完毕，否则新的解码又要开始了
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//此处不用申请内存的方式解决
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// decoder.utcTime = utcTime;
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// decoder.num_samples = num_samples;
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// decoder.mon_cfg = (monitor_config_t) {
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// .f_min = 100,//分析的最低频率边界
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// .f_max = 3000,//分析的最大频率边界
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// .sample_rate = sample_rate,//采样率12000Hz
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// .time_osr = kTime_osr,//时间过采样率=2
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// .freq_osr = kFreq_osr,//频率过采样率=2
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// .protocol = is_ft8 ? PROTO_FT8 : PROTO_FT4
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// };
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// //LOGD("Init decoder . address : %lld", decoder);
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// monitor_init(&decoder.mon, &decoder.mon_cfg);
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//
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//
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// return &decoder;
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//此部分，是老的解决方式，是动态申请内存。
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decoder_t *decoder;
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decoder = malloc(sizeof(decoder_t));
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decoder->utcTime = utcTime;
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decoder->num_samples = num_samples;
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decoder->mon_cfg = (monitor_config_t) {
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.f_min = 100,//分析的最低频率边界
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.f_max = 3000,//分析的最大频率边界
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.sample_rate = sample_rate,//采样率12000Hz
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.time_osr = kTime_osr,//时间过采样率=2
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.freq_osr = kFreq_osr,//频率过采样率=2
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.protocol = is_ft8 ? PROTO_FT8 : PROTO_FT4
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};
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decoder->kLDPC_iterations = fast_kLDPC_iterations;
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//LOGD("Init decoder . address : %lld", decoder);
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monitor_init(&decoder->mon, &decoder->mon_cfg);
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return decoder;
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}
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void delete_decoder(decoder_t *decoder) {
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//LOGD("Free decoder , address:%lld", decoder);
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monitor_free(&decoder->mon);
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free(decoder);
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}
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void decoder_monitor_press(float signal[], decoder_t *decoder) {
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// 以每一个FSK符号占用的数据量为单位循环。
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//block_size每个符号的样本数12000*0.16=1920
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for (int frame_pos = 0;
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frame_pos + decoder->mon.block_size <=
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decoder->num_samples; frame_pos += decoder->mon.block_size) {
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// Process the waveform data frame by frame - you could have a live loop here with data from an audio device
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// 逐帧处理波形数据，这个位置可以使用音频设备的数据环。
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//以每一个符号时间长度（0.16）内的数据做瀑布数据，最后会形成一个信号量mag数组。
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// mag数组的总长度是：最大符号块数93*时间过采样率2*频率过采样率2*分析块960，也就是Waterfall size = 357120
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//一次调用monitor_process，处理的是一个符号长度的信号量数据，生成2*2*960=3840个mag数据。
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//一共有93个符号的循环，mag数组的大小：2*2*960*93=357120
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//mag数据保存在monitor.wf.mag中。
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monitor_process(&decoder->mon, signal + frame_pos);
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}
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// /data/user/0/com.bg7yoz.ft8cn/cache/
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//把fft数据保存下来
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//FILE * fp2 = fopen("/data/user/0/com.bg7yoz.ft8cn/cache/fft001.txt", "w");//打开输出文件
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//for (int i = 0; i < 3840; ++i) {
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// for (int j = 0; j < 93; ++j) {
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// fprintf (fp2,"%d\n", decoder->mon.wf.mag[i*j]);//把数组a逆序写入到输出文件当中
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// }
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//}
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//fclose(fp2);//关闭输出文件，相当于保存
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LOG(LOG_DEBUG, "Waterfall accumulated %d symbols\n", decoder->mon.wf.num_blocks);//积累的信号
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LOG(LOG_INFO, "Max magnitude: %.1f dB\n", decoder->mon.max_mag);//最大信号值dB
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}
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int decoder_ft8_find_sync(decoder_t *decoder) {
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//检测ft8信号，kMax_candidates最大候选人数量=120，candidate_list候选人列表(size=120)，kMin_score候选人的最低同步分数阈值=10
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decoder->num_candidates = ft8_find_sync(&decoder->mon.wf, kMax_candidates,
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decoder->candidate_list, kMin_score);
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LOG(LOG_DEBUG, "ft8_find_sync finished. %d candidates\n", decoder->num_candidates);
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// Hash table for decoded messages (to check for duplicates)
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// 解码消息的哈希表（用于检查重复项）
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//int num_decoded = 0;
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//message_t decoded[kMax_decoded_messages];//kMax_decoded_messages=50
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// 哈希表指针列表（指针数组）
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//message_t *decoded_hashtable[kMax_decoded_messages];
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// Initialize hash table pointers
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// 初始化哈希表指针列表
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for (int i = 0; i < kMax_decoded_messages; ++i) {
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decoder->decoded_hashtable[i] = NULL;
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}
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return decoder->num_candidates;
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}
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ft8_message decoder_ft8_analysis(int idx, decoder_t *decoder) {
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ft8_message ft8Message;
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ft8Message.isValid = false;
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ft8Message.utcTime = decoder->utcTime;
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// 候选列表candidate_list，已经从ft8_fing_sync获得。
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ft8Message.candidate = decoder->candidate_list[idx];
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if (ft8Message.candidate.score < kMin_score) {
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//ft8Message.isValid = false;
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return ft8Message;
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}
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ft8Message.freq_hz =
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(ft8Message.candidate.freq_offset +
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(float) ft8Message.candidate.freq_sub / decoder->mon.wf.freq_osr) /
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decoder->mon.symbol_period;
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ft8Message.time_sec =
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((ft8Message.candidate.time_offset + (float) ft8Message.candidate.time_sub)
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* decoder->mon.symbol_period) / decoder->mon.wf.time_osr;
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//ft8Message.snr=ft8Message.candidate.snr;
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//这是原来代码的时间偏移，同样的数据与JTDX的时间差异很大，改用上面的代码，稍微接近一些
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//(ft8Message.candidate.time_offset +
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//(float) ft8Message.candidate.time_sub / decoder->mon.wf.time_osr) *
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//decoder->mon.symbol_period;
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// 如果解码失败，跳到下一次循环 kLDPC_iterations=20 LDPC（低密度奇偶校验）的迭代次数。
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if (!ft8_decode(&decoder->mon.wf, &ft8Message.candidate
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//, &ft8Message.message, kLDPC_iterations,
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, &ft8Message.message, decoder->kLDPC_iterations,
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&ft8Message.status)) {
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// printf("000000 %3d %+4.2f %4.0f ~ ---\n", cand->score, time_sec, freq_hz);
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if (ft8Message.status.ldpc_errors > 0) {
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// LDPC:低密度奇偶校验
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LOG(LOG_DEBUG, "LDPC decode: %d errors\n", ft8Message.status.ldpc_errors);
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} else if (ft8Message.status.crc_calculated != ft8Message.status.crc_extracted) {
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LOG(LOG_DEBUG, "CRC mismatch!\n");
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} else if (ft8Message.status.unpack_status != 0) {
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LOG(LOG_DEBUG, "Error while unpacking!\n");
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}
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//ft8Message.isValid = false;
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return ft8Message;
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}
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ft8Message.snr = ft8Message.candidate.snr;
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LOG(LOG_DEBUG, "Checking hash table for %4.1fs / %4.1fHz [%d]...\n", ft8Message.time_sec,
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ft8Message.freq_hz,
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ft8Message.candidate.score);
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int idx_hash =
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ft8Message.message.hash % kMax_decoded_messages;//为啥是取模？稍后研究kMax_decoded_messages=50
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bool found_empty_slot = false;
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bool found_duplicate = false;
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//检查哈希表，只有空插槽，或重复插槽（哈希值相同，并且消息相同）
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do {
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if (decoder->decoded_hashtable[idx_hash] == NULL) {
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LOG(LOG_DEBUG, "Found an empty slot\n");
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found_empty_slot = true;
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} else if ((decoder->decoded_hashtable[idx_hash]->hash == ft8Message.message.hash) &&
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(0 ==
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strcmp(decoder->decoded_hashtable[idx_hash]->text, ft8Message.message.text))) {
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LOG(LOG_DEBUG, "Found a duplicate [%s]\n", ft8Message.message.text);
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found_duplicate = true;
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} else {
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LOG(LOG_DEBUG, "Hash table clash!\n");
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// Move on to check the next entry in hash table
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idx_hash = (idx_hash + 1) % kMax_decoded_messages;
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}
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} while (!found_empty_slot && !found_duplicate);
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if (found_empty_slot) {
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// Fill the empty hashtable slot
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memcpy(&decoder->decoded[idx_hash], &ft8Message.message, sizeof(ft8Message.message));
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decoder->decoded_hashtable[idx_hash] = &decoder->decoded[idx_hash];
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++decoder->num_decoded;
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ft8Message.isValid = true;
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LOG_PRINTF("%3d %+4.2f %4.0f ~ %s report:%d grid:%s,toHash:%x,fromHash:%x",
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ft8Message.snr,
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ft8Message.time_sec, ft8Message.freq_hz, ft8Message.message.text,
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ft8Message.message.report, ft8Message.message.maidenGrid,
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ft8Message.message.call_to_hash.hash12, ft8Message.message.call_de_hash.hash12);
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}
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memcpy(decoder->a91, ft8Message.message.a91, FTX_LDPC_K_BYTES);
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return ft8Message;
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}
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void decoder_ft8_reset(decoder_t *decoder, long utcTime, int num_samples) {
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LOG(LOG_DEBUG, "Monitor is resetting...");
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decoder->mon.wf.num_blocks = 0;
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//decoder->mon.max_mag = 0;
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decoder->mon.max_mag = -120.0f;
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decoder->utcTime = utcTime;
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decoder->num_samples = num_samples;
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}
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/**
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* 对174码，重新编生成79码
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* @param a174 174个int
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* @param a79 79个int
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*/
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void recode(int a174[], int a79[]) {
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int i174 = 0;
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//int costas[] = { 3, 1, 4, 0, 6, 5, 2 };
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//std::vector<int> out79;
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for (int i79 = 0; i79 < 79; i79++) {
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if (i79 < 7) {
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//out79.push_back(costas[i79]);
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a79[i79] = kFT8CostasPattern[i79];
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} else if (i79 >= 36 && i79 < 36 + 7) {
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//out79.push_back(costas[i79-36]);
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a79[i79] = kFT8CostasPattern[i79 - 36];
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} else if (i79 >= 72) {
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//out79.push_back(costas[i79-72]);
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a79[i79] = kFT8CostasPattern[i79 - 72];
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} else {
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int sym = (a174[i174 + 0] << 2) | (a174[i174 + 1] << 1) | (a174[i174 + 2] << 0);
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i174 += 3;
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// gray code
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int map[] = {0, 1, 3, 2, 5, 6, 4, 7};
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sym = map[sym];
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//out79.push_back(sym);
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a79[i79] = sym;
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}
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}
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};
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