Fix TX handling for multiple packets
- (only) time-based end-of-transmission tracking
- removed tx_done flag
- count zero-buffers correctly in time-tracking
- add 10 ms of headroom so the transmission does not stop before buffer was
completely transmitted (race condition)
- fix race condition with tx_start_time in sdr_start_tx()
- simplified packet queuing (no chunking)
- read multiple packets before starting transmission (to fill buffers initially)
Thanks to rudi_s!
This commit is contained in:
Thomas Kolb
parent
1f5f922cdf
commit
11f19c03a0
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@ -155,49 +155,17 @@ void cb_rx(rx_evt_t evt, uint8_t *packet_data, size_t packet_len)
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static int debug_fd;
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#define CHUNKSIZE_BB 16384
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#define CHUNKSIZE_RF (CHUNKSIZE_BB * SDR_OVERSAMPLING)
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static result_t transmit_in_chunks(sdr_ctx_t *sdr, const float complex *samples, size_t len)
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static result_t transmit(sdr_ctx_t *sdr, const float complex *samples, size_t len)
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{
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size_t transmitted = 0;
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unsigned retry_counter = 0;
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size_t to_transmit_rf = len * SDR_OVERSAMPLING;
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float complex rf_samples[to_transmit_rf];
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float complex rf_samples[CHUNKSIZE_RF];
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RESULT_CHECK(sdr_baseband_to_rf(sdr, samples, len, rf_samples, &to_transmit_rf));
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while(transmitted < len) {
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size_t to_transmit_bb = len - transmitted;
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if(to_transmit_bb > CHUNKSIZE_BB) {
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to_transmit_bb = CHUNKSIZE_BB;
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}
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result_t result = sdr_transmit(sdr, rf_samples, to_transmit_rf, 100000);
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size_t to_transmit_rf = CHUNKSIZE_RF;
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RESULT_CHECK(sdr_baseband_to_rf(sdr, samples + transmitted, to_transmit_bb, rf_samples, &to_transmit_rf));
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result_t result = sdr_transmit(sdr, rf_samples, to_transmit_rf, 100000);
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if(result != OK) {
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retry_counter++;
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fprintf(stderr, "sdr_transmit failed %d times\n", retry_counter);
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if(retry_counter > 3) {
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return result;
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} else {
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continue;
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}
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}
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//write(debug_fd, rf_samples, to_transmit_rf*sizeof(rf_samples[0]));
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fprintf(stderr, "t");
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transmitted += to_transmit_bb;
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retry_counter = 0;
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}
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return OK;
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fprintf(stderr, "t");
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return result;
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}
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@ -311,9 +279,23 @@ int main(int argc, char **argv)
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dump_array_cf(whole_burst, burst_len, 1.0f, "/tmp/tx.cpx");
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// ensure that the buffer is full before TX is turned on to avoid transmitting empty buffers
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RESULT_CHECK(transmit_in_chunks(&sdr, whole_burst, burst_len));
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RESULT_CHECK(transmit(&sdr, whole_burst, burst_len));
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if(!on_air) {
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size_t buffer_used_samples = sdr_get_tx_buffer_used_space(&sdr);
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const size_t min_required_samples = 4*128*1024;
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int ret2 = poll(&pfd, 1, 0);
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if(ret2 < 0) {
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perror("poll");
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break;
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} else if(ret2 != 0 && (buffer_used_samples < min_required_samples)) {
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// enqueue more packets before starting TX
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fprintf(stderr, "Pre-buffering more packets: %zd / %zd samples.\n", buffer_used_samples, min_required_samples);
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continue;
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}
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fprintf(stderr, "RX -> TX\n");
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RESULT_CHECK(sdr_stop_rx(&sdr));
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// transmit packets on the frequency where the last packet was received.
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@ -324,6 +306,7 @@ int main(int argc, char **argv)
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on_air = true;
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} else if(on_air) { // ret == 0
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fprintf(stderr, "TX -> RX\n");
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RESULT_CHECK(sdr_flush_tx_buffer(&sdr));
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RESULT_CHECK(sdr_stop_tx(&sdr));
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@ -94,14 +94,10 @@ static int tx_callback(hackrf_transfer *transfer)
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return HACKRF_ERROR_OTHER;
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}
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if(samples_read == 0) {
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// buffer has run empty, so this is the end of the transmission
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sdr_ctx->tx_done = true;
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}
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if(sdr_ctx->tx_start_time == 0.0) {
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sdr_ctx->tx_start_time = get_hires_time();
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sdr_ctx->tx_duration = 0.0f;
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sdr_ctx->tx_duration = 10e-3; // give a little headroom
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fprintf(stderr, "TX time tracking reset: start = %.3f.\n", sdr_ctx->tx_start_time);
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}
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for(size_t i = 0; i < samples_read; i++) {
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@ -109,7 +105,10 @@ static int tx_callback(hackrf_transfer *transfer)
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transfer->buffer[2*i + 1] = clamp_float2int8(cimag(samples[i]));
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}
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sdr_ctx->tx_duration += (double)samples_read / SDR_TX_SAMPLING_RATE;
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if(samples_read != 0) {
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// only add time if any actual samples were transmitted
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sdr_ctx->tx_duration += (double)samples_requested / SDR_TX_SAMPLING_RATE;
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}
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fprintf(stderr, "copied %u samples to HackRF.\n", samples_read);
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@ -266,11 +265,12 @@ result_t sdr_start_tx(sdr_ctx_t *ctx, size_t burst_size)
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result = hackrf_set_txvga_gain(ctx->hackrf, SDR_GAIN_TX_VGA);
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CHECK_HACKRF_RESULT(result, "hackrf_set_txvga_gain");
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ctx->tx_start_time = 0.0f; // will be updated by tx_callback
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result = hackrf_start_tx(ctx->hackrf, tx_callback, ctx);
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CHECK_HACKRF_RESULT(result, "hackrf_start_tx");
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ctx->status = SDR_STATUS_TX;
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ctx->tx_start_time = 0.0f; // will be updated by tx_callback
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return OK;
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}
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@ -304,8 +304,6 @@ result_t sdr_transmit(sdr_ctx_t *ctx, const float complex *samples, size_t nsamp
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return ERR_LIQUID;
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}
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ctx->tx_done = false;
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if(sem_post(&ctx->buf_sem) < 0) {
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perror("sem_post");
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return ERR_SDR;
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@ -358,8 +356,25 @@ result_t sdr_receive(sdr_ctx_t *ctx, float complex *samples, size_t *nsamples, l
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result_t sdr_flush_tx_buffer(sdr_ctx_t *ctx)
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{
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// block until all samples have been transmitted
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while(!ctx->tx_done || (get_hires_time() < (ctx->tx_start_time + ctx->tx_duration))) {
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fsleep(1e-3);
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while(true) {
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if(sem_wait(&ctx->buf_sem) < 0) {
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perror("sem_wait");
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return 0;
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}
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double now = get_hires_time();
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double end = ctx->tx_start_time + ctx->tx_duration;
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if(sem_post(&ctx->buf_sem) < 0) {
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perror("sem_post");
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return 0;
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}
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if(now >= end) {
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break;
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}
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sleep_until(end);
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}
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return OK;
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@ -386,6 +401,26 @@ size_t sdr_get_tx_buffer_free_space(sdr_ctx_t *ctx)
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}
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size_t sdr_get_tx_buffer_used_space(sdr_ctx_t *ctx)
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{
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size_t used_samples = 0;
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if(sem_wait(&ctx->buf_sem) < 0) {
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perror("sem_wait");
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return 0;
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}
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used_samples = cbuffercf_size(ctx->tx_buf);
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if(sem_post(&ctx->buf_sem) < 0) {
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perror("sem_post");
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return 0;
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}
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return used_samples;
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}
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result_t sdr_rf_to_baseband(sdr_ctx_t *ctx,
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const float complex *rf_samples, size_t nrf,
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float complex *bb_samples, size_t *nbb)
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@ -31,7 +31,6 @@ typedef struct {
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sem_t buf_sem;
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sdr_status_t status;
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bool tx_done;
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double tx_duration;
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double tx_start_time; // time when tx_callback() was first called
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} sdr_ctx_t;
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@ -50,6 +49,7 @@ result_t sdr_receive(sdr_ctx_t *ctx, float complex *samples, size_t *nsamples, l
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result_t sdr_flush_tx_buffer(sdr_ctx_t *ctx);
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size_t sdr_get_tx_buffer_free_space(sdr_ctx_t *ctx);
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size_t sdr_get_tx_buffer_used_space(sdr_ctx_t *ctx);
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/*!
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* \brief Convert and resample a received signal to baseband.
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