Generates RTTY from a GPS receiver
Dependencies: mbed-dsp mbed-rtos mbed
Diff: main.cpp
- Revision:
- 3:33d80761aa06
- Parent:
- 2:1f19f8e52c75
- Child:
- 4:ed77fd381cc5
--- a/main.cpp Sat Jan 11 05:55:54 2014 +0000 +++ b/main.cpp Sat Jan 11 18:48:08 2014 +0000 @@ -10,15 +10,18 @@ #define GPS_CB_SIZE (16) /* size of gps circular buffer in characters */ #define RTTY_CB_SIZE (2048) /* characters in rtty buffer */ #define GPS_BAUD (9600) /* gps serial port speed in bps */ -#define RADIO_TX_WAIT (5000) /* time between radio transmissions in ms */ -#define RADIO_KEYUP_DELAY (1000) /* time to wait for radio transmitter to turn on */ -#define PRINT_NMEA_WAIT (2000) /* time between console debug messages */ -#define AUDIO_FS (22050) /* audio sample rate in hz */ -#define RTTY_BAUD (45.45) /* rtty bit rate in bps */ -#define MARK_FREQ (2295) /* mark frequency (1) in hz */ -#define SPACE_FREQ (2125) /* space frequency (0) in hz */ -#define AUDIO_VOL (0.25) /* range 0-1 */ -#define RTTY_NUM_ZEROS (3) /* number of empty characters to append before each rtty message */ +#define RADIO_TX_WAIT (1000) /* time between radio transmissions in ms */ +#define PRINT_NMEA_WAIT (2000) /* time between console debug messages in ms */ +#define CALLSIGN_WAIT (600) /* time between sending amateur radio callsign in s */ +#define AUDIO_FS (8000) /* audio sample rate in hz */ +#define RTTY_BAUD (110) /* rtty bit rate in bps */ +#define MARK_FREQ (2850) /* mark frequency (1) in hz */ +#define SPACE_FREQ (2000) /* space frequency (0) in hz */ +#define AUDIO_VOL (1) /* range 0-1 */ +#define RTTY_NUM_ZEROS_BEFORE (25) /* number of empty characters to append before each rtty message. helps receivers sync. */ +#define RTTY_NUM_ZEROS_AFTER (8) /* number of empty characters to append after each rtty message. */ +#define CALLSIGN "KC0WYS" /* my amateur radio callsign */ +#define CALLSIGN_TAG "HAMID" /* 5-character tag used in the fake nmea sentence */ using namespace std; @@ -99,7 +102,7 @@ if(angle > 2 * PI) angle -= 2*PI; dac = (arm_sin_f32(angle) + 1.0) / 2.0 * AUDIO_VOL; // write sample to dac ptt = 0; - rtty_led = 1; + rtty_led = !rtty_led; } else { dac = 0; ptt = 1; @@ -128,17 +131,7 @@ } } -// Adds empty characters to RTTY buffer. -void rtty_add_padding() -{ - for(int i = 0; i < RTTY_NUM_ZEROS; ++i) { - if(++r_cb_thr_i >= RTTY_CB_SIZE) r_cb_thr_i = 0; // incr/loop circular buffer index - r_cb[r_cb_thr_i] = 0; // append a zero - } -} - -// Adds NMEA sentences periodically to a buffer for the other RTTY -// functions to process. +// Adds NMEA sentences periodically to a buffer for the other RTTY functions to process. void rtty_tx_thread(void const *argument) { while(1) { @@ -148,18 +141,37 @@ for (map<string,string>::iterator iter = nmea_data.begin(); iter != nmea_data.end(); ++iter) { txbuf << (iter->second); // fill the packet with the most recent nmea sentences } + nmea_data.clear(); // empty the map nmea_data_mutex.unlock(); - rtty_add_padding(); // pad message with empty characters + for(int i = 0; i < RTTY_NUM_ZEROS_BEFORE; ++i) { // add empty characters + if(++r_cb_thr_i >= RTTY_CB_SIZE) r_cb_thr_i = 0; // incr/loop circular buffer index + r_cb[r_cb_thr_i] = 0; // append a zero character + } for(const char* it = txbuf.str().c_str(); *it; ++it) { // add all characters to buffer if(++r_cb_thr_i >= RTTY_CB_SIZE) r_cb_thr_i = 0; // incr/loop circular buffer index r_cb[r_cb_thr_i] = *it; } - rtty_add_padding(); + for(int i = 0; i < RTTY_NUM_ZEROS_AFTER; ++i) { // add empty characters + if(++r_cb_thr_i >= RTTY_CB_SIZE) r_cb_thr_i = 0; // incr/loop circular buffer index + r_cb[r_cb_thr_i] = 0; // append a zero character + } while(!txen) Thread::wait(100); // wait for transmission to start while( txen) Thread::wait(100); // wait for transmission to end } } +// Periodically inserts HAM radio callsign into NMEA sentence map. +// Required by FCC to send callsign at least every 30 minutes. +void insert_callsign_thread(void const *argument) +{ + while(1) { + nmea_data_mutex.lock(); + nmea_data[CALLSIGN_TAG] = "$" CALLSIGN_TAG "," CALLSIGN "," CALLSIGN "," CALLSIGN ",*00\r\n"; // dummy nmea sentence + nmea_data_mutex.unlock(); + for(int i = 0; i < CALLSIGN_WAIT; ++i) Thread::wait(1000); // wait for CALLSIGN_WAIT seconds + } +} + // Writes debug messages periodically to the console. Useful for debug. void print_nmea_thread(void const *argument) { @@ -180,6 +192,7 @@ Thread gps_thread(gps_rx_thread); // gps receive thread Thread rtty_thread(rtty_tx_thread); // rtty transmit thread Thread print_thread(print_nmea_thread); // debug print thread + Thread callsign_thread(insert_callsign_thread); // amateur callsign thread gps.baud(GPS_BAUD); // set gps bit rate gps.attach(&gps_rx_isr); // set up gps receive interrupt service routine sample_tick.attach_us(&rtty_sample_tick,1000000/AUDIO_FS); // begin generating audio