srsRAN/srslte/examples/usrp_capture_sync.c

/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2014 The srsLTE Developers. See the
 * COPYRIGHT file at the top-level directory of this distribution.
 *
 * \section LICENSE
 *
 * This file is part of the srsLTE library.
 *
 * srsLTE is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * srsLTE is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * A copy of the GNU Lesser General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */

#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <math.h>
#include <time.h>

#include <stdbool.h>

#include "srslte/srslte.h"
#include "srslte/cuhd/cuhd.h"

static bool keep_running = true;
char *output_file_name = NULL;
char *uhd_args="";
float uhd_gain=40.0, uhd_freq=-1.0;
int nof_prb = 6;
int nof_subframes = -1;
int N_id_2 = -1; 

void int_handler(int dummy) {
  keep_running = false;
}

void usage(char *prog) {
  printf("Usage: %s [agrnv] -l N_id_2 -f rx_frequency_hz -o output_file\n", prog);
  printf("\t-a UHD args [Default %s]\n", uhd_args);
  printf("\t-g UHD Gain [Default %.2f dB]\n", uhd_gain);
  printf("\t-p nof_prb [Default %d]\n", nof_prb);
  printf("\t-n nof_subframes [Default %d]\n", nof_subframes);
  printf("\t-v srslte_verbose\n");
}

void parse_args(int argc, char **argv) {
  int opt;
  while ((opt = getopt(argc, argv, "agpnvfol")) != -1) {
    switch (opt) {
    case 'o':
      output_file_name = argv[optind];
      break;
    case 'a':
      uhd_args = argv[optind];
      break;
    case 'g':
      uhd_gain = atof(argv[optind]);
      break;
    case 'p':
      nof_prb = atoi(argv[optind]);
      break;
    case 'f':
      uhd_freq = atof(argv[optind]);
      break;
    case 'n':
      nof_subframes = atoi(argv[optind]);
      break;
    case 'l':
      N_id_2 = atoi(argv[optind]);
      break;
    case 'v':
      srslte_verbose++;
      break;
    default:
      usage(argv[0]);
      exit(-1);
    }
  }
  if (uhd_freq < 0 || N_id_2 == -1 || output_file_name == NULL) {
    usage(argv[0]);
    exit(-1);
  }
}

int cuhd_recv_wrapper(void *h, void *data, uint32_t nsamples, srslte_timestamp_t *t) {
  DEBUG(" ----  Receive %d samples  ---- \n", nsamples);
  return cuhd_recv(h, data, nsamples, 1);
}

enum receiver_state { DECODE_MIB, SAVE_FILE} state; 

int main(int argc, char **argv) {
  cf_t *buffer; 
  int subframe_count, n;
  void *uhd;
  srslte_filesink_t sink;
  srslte_ue_mib_t ue_mib; 
  srslte_ue_sync_t ue_sync; 
  srslte_cell_t cell; 
  enum receiver_state state; 
  uint8_t bch_payload[BCH_PAYLOAD_LEN];

  signal(SIGINT, int_handler);

  parse_args(argc, argv);
  
  subframe_count = 0;

  srslte_filesink_init(&sink, output_file_name, SRSLTE_COMPLEX_FLOAT_BIN);

  printf("Opening UHD device...\n");
  if (cuhd_open(uhd_args, &uhd)) {
    fprintf(stderr, "Error opening uhd\n");
    exit(-1);
  }
  printf("Set RX freq: %.6f MHz\n", cuhd_set_rx_freq(uhd, uhd_freq) / 1000000);
  printf("Set RX gain: %.1f dB\n", cuhd_set_rx_gain(uhd, uhd_gain));
  printf("Set RX rate: %.6f MHz\n", cuhd_set_rx_srate(uhd, srslte_sampling_freq_hz(nof_prb)) / 1000000);
  cuhd_rx_wait_lo_locked(uhd);
  cuhd_start_rx_stream(uhd);

  cell.cp = SRSLTE_CP_NORM; 
  cell.id = N_id_2;
  cell.nof_prb = nof_prb; 
  cell.nof_ports = 1; 
  
  if (srslte_ue_sync_init(&ue_sync, cell, cuhd_recv_wrapper, uhd)) {
    fprintf(stderr, "Error initiating ue_sync\n");
    exit(-1); 
  }
  if (srslte_ue_mib_init(&ue_mib, cell)) {
    fprintf(stderr, "Error initaiting UE MIB decoder\n");
    exit(-1);
  }    
  state = DECODE_MIB; 
  bool decoded_mib = false; 
  uint32_t sfn, sfn_offset; 
  
  printf("Waiting for SFN=0\n");
  while((subframe_count < nof_subframes || nof_subframes == -1)
        && keep_running)
  {
    n = srslte_ue_sync_get_buffer(&ue_sync, &buffer);
    if (n < 0) {
      fprintf(stderr, "Error receiving samples\n");
      exit(-1);
    }
    if (n == 1) {
      switch (state) {
        case DECODE_MIB:
          if (srslte_ue_sync_get_sfidx(&ue_sync) == 0) {
            srslte_pbch_decode_reset(&ue_mib.pbch);
            n = srslte_ue_mib_decode(&ue_mib, buffer, bch_payload, NULL, &sfn_offset);
            if (n < 0) {
              fprintf(stderr, "Error decoding UE MIB\n");
              exit(-1);
            } else if (n == SRSLTE_UE_MIB_FOUND) {             
              srslte_pbch_mib_unpack(bch_payload, &cell, &sfn);
              sfn = (sfn + sfn_offset)%1024;   
              decoded_mib = true; 
            }
          }
          if (decoded_mib && srslte_ue_sync_get_sfidx(&ue_sync) == 9 && sfn == 1023) {
            srslte_pbch_mib_fprint(stdout, &cell, sfn, cell.id);
            printf("Decoded MIB. SFN: %d\n", sfn);
            state = SAVE_FILE;                             
          }
          break;
        case SAVE_FILE:
          printf("Writing to file %4d subframes...\r", subframe_count);
          srslte_filesink_write(&sink, buffer, SRSLTE_SF_LEN_PRB(nof_prb));
          subframe_count++;              
          break;
      }
      if (srslte_ue_sync_get_sfidx(&ue_sync) == 9) {
        sfn++; 
        if (sfn == 1024) {
          sfn = 0; 
        } 
      }

    }
  }
  
  srslte_filesink_free(&sink);
  cuhd_close(uhd);
  srslte_ue_sync_free(&ue_sync);

  printf("Ok - wrote %d subframes\n", subframe_count);
  exit(0);
}