diff options
Diffstat (limited to 'demo/freedv_datac1_tx.c')
| -rw-r--r-- | demo/freedv_datac1_tx.c | 112 |
1 files changed, 57 insertions, 55 deletions
diff --git a/demo/freedv_datac1_tx.c b/demo/freedv_datac1_tx.c index 616eec8..a7a2d10 100644 --- a/demo/freedv_datac1_tx.c +++ b/demo/freedv_datac1_tx.c @@ -5,23 +5,23 @@ DATE CREATED: April 2021 Demonstrates transmitting frames of raw data bytes using the FreeDV API datac1 - mode. The data on stdin is transmitted as a sequence of modulated bursts. + mode. The data on stdin is transmitted as a sequence of modulated bursts. Format of each burst: ...|preamble|data frame|postamble|silence|.... - + There is just one data frame per burst in this demo. - + usage: - + cd codec2/build_linux head -c $((510*10)) </dev/urandom > binaryIn.bin - cat binaryIn.bin | ./demo/freedv_datac1_tx | ./demo/freedv_datac1_rx > binaryOut.bin - diff binaryIn.bin binaryOut.bin - + cat binaryIn.bin | ./demo/freedv_datac1_tx | ./demo/freedv_datac1_rx > +binaryOut.bin diff binaryIn.bin binaryOut.bin + Listen to the modulated Tx signal: - + cat binaryIn.bin | ./demo/freedv_datac1_tx | aplay -f S16_LE - + \*---------------------------------------------------------------------------*/ /* @@ -42,55 +42,57 @@ */ #include <assert.h> -#include <stdlib.h> -#include <stdio.h> #include <stdint.h> +#include <stdio.h> +#include <stdlib.h> #include "freedv_api.h" int main(int argc, char *argv[]) { - struct freedv *freedv; - - freedv = freedv_open(FREEDV_MODE_DATAC1); - assert(freedv != NULL); - - size_t bytes_per_modem_frame = freedv_get_bits_per_modem_frame(freedv)/8; - size_t payload_bytes_per_modem_frame = bytes_per_modem_frame - 2; /* 16 bits used for the CRC */ - size_t n_mod_out = freedv_get_n_tx_modem_samples(freedv); - uint8_t bytes_in[bytes_per_modem_frame]; - short mod_out_short[n_mod_out]; - - for(int b=0; b<10; b++) { - /* send preamble */ - int n_preamble = freedv_rawdatapreambletx(freedv, mod_out_short); - fwrite(mod_out_short, sizeof(short), n_preamble, stdout); - - /* read our input data frame from stdin */ - size_t nread = fread(bytes_in, sizeof(uint8_t), payload_bytes_per_modem_frame, stdin); - if (nread != payload_bytes_per_modem_frame) break; - - /* The raw data modes require a CRC in the last two bytes */ - uint16_t crc16 = freedv_gen_crc16(bytes_in, payload_bytes_per_modem_frame); - bytes_in[bytes_per_modem_frame-2] = crc16 >> 8; - bytes_in[bytes_per_modem_frame-1] = crc16 & 0xff; - - /* modulate and send a data frame */ - freedv_rawdatatx(freedv, mod_out_short, bytes_in); - fwrite(mod_out_short, sizeof(short), n_mod_out, stdout); - - /* send postamble */ - int n_postamble = freedv_rawdatapostambletx(freedv, mod_out_short); - fwrite(mod_out_short, sizeof(short), n_postamble, stdout); - - /* create some silence between bursts */ - int inter_burst_delay_ms = 200; - int samples_delay = FREEDV_FS_8000*inter_burst_delay_ms/1000; - short sil_short[samples_delay]; - for(int i=0; i<samples_delay; i++) sil_short[i] = 0; - fwrite(sil_short, sizeof(short), samples_delay, stdout); - } - - freedv_close(freedv); - - return 0; + struct freedv *freedv; + + freedv = freedv_open(FREEDV_MODE_DATAC1); + assert(freedv != NULL); + + size_t bytes_per_modem_frame = freedv_get_bits_per_modem_frame(freedv) / 8; + size_t payload_bytes_per_modem_frame = + bytes_per_modem_frame - 2; /* 16 bits used for the CRC */ + size_t n_mod_out = freedv_get_n_tx_modem_samples(freedv); + uint8_t bytes_in[bytes_per_modem_frame]; + short mod_out_short[n_mod_out]; + + for (int b = 0; b < 10; b++) { + /* send preamble */ + int n_preamble = freedv_rawdatapreambletx(freedv, mod_out_short); + fwrite(mod_out_short, sizeof(short), n_preamble, stdout); + + /* read our input data frame from stdin */ + size_t nread = + fread(bytes_in, sizeof(uint8_t), payload_bytes_per_modem_frame, stdin); + if (nread != payload_bytes_per_modem_frame) break; + + /* The raw data modes require a CRC in the last two bytes */ + uint16_t crc16 = freedv_gen_crc16(bytes_in, payload_bytes_per_modem_frame); + bytes_in[bytes_per_modem_frame - 2] = crc16 >> 8; + bytes_in[bytes_per_modem_frame - 1] = crc16 & 0xff; + + /* modulate and send a data frame */ + freedv_rawdatatx(freedv, mod_out_short, bytes_in); + fwrite(mod_out_short, sizeof(short), n_mod_out, stdout); + + /* send postamble */ + int n_postamble = freedv_rawdatapostambletx(freedv, mod_out_short); + fwrite(mod_out_short, sizeof(short), n_postamble, stdout); + + /* create some silence between bursts */ + int inter_burst_delay_ms = 200; + int samples_delay = FREEDV_FS_8000 * inter_burst_delay_ms / 1000; + short sil_short[samples_delay]; + for (int i = 0; i < samples_delay; i++) sil_short[i] = 0; + fwrite(sil_short, sizeof(short), samples_delay, stdout); + } + + freedv_close(freedv); + + return 0; } |