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-rw-r--r--src/CMakeLists.txt22
-rw-r--r--src/fl2k_iq.c (renamed from src/fl2k_am.c)152
2 files changed, 91 insertions, 83 deletions
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 72aaba1..543226e 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -80,35 +80,35 @@ add_executable(fl2k_tcp fl2k_tcp.c)
add_executable(fl2k_test fl2k_test.c)
add_executable(fl2k_fm fl2k_fm.c rds_waveforms.c rds_mod.c)
add_executable(fl2k_garage fl2k_garage.c)
-add_executable(fl2k_am fl2k_am.c)
-set(INSTALL_TARGETS libosmo-fl2k_shared libosmo-fl2k_static fl2k_file fl2k_tcp fl2k_test fl2k_fm fl2k_garage fl2k_am)
+add_executable(fl2k_iq fl2k_iq.c)
+set(INSTALL_TARGETS libosmo-fl2k_shared libosmo-fl2k_static fl2k_file fl2k_tcp fl2k_test fl2k_fm fl2k_garage fl2k_iq)
-target_link_libraries(fl2k_file libosmo-fl2k_shared
+target_link_libraries(fl2k_file libosmo-fl2k_shared
${LIBUSB_LIBRARIES}
${CMAKE_THREAD_LIBS_INIT}
)
-target_link_libraries(fl2k_tcp libosmo-fl2k_shared
+target_link_libraries(fl2k_tcp libosmo-fl2k_shared
${LIBUSB_LIBRARIES}
${CMAKE_THREAD_LIBS_INIT}
)
-target_link_libraries(fl2k_test libosmo-fl2k_shared
+target_link_libraries(fl2k_test libosmo-fl2k_shared
${LIBUSB_LIBRARIES}
${CMAKE_THREAD_LIBS_INIT}
)
-target_link_libraries(fl2k_fm libosmo-fl2k_shared
+target_link_libraries(fl2k_fm libosmo-fl2k_shared
${LIBUSB_LIBRARIES}
${CMAKE_THREAD_LIBS_INIT}
)
-target_link_libraries(fl2k_garage libosmo-fl2k_shared
+target_link_libraries(fl2k_garage libosmo-fl2k_shared
${LIBUSB_LIBRARIES}
${CMAKE_THREAD_LIBS_INIT}
)
-target_link_libraries(fl2k_am libosmo-fl2k_shared
+target_link_libraries(fl2k_iq libosmo-fl2k_shared
${LIBUSB_LIBRARIES}
${CMAKE_THREAD_LIBS_INIT}
)
@@ -118,7 +118,7 @@ if(UNIX)
target_link_libraries(fl2k_test m)
target_link_libraries(fl2k_fm m)
target_link_libraries(fl2k_garage m)
-target_link_libraries(fl2k_am m)
+target_link_libraries(fl2k_iq m)
endif()
if(WIN32 AND NOT MINGW)
@@ -127,13 +127,13 @@ target_link_libraries(fl2k_tcp ws2_32 libgetopt_static)
target_link_libraries(fl2k_test libgetopt_static)
target_link_libraries(fl2k_fm libgetopt_static)
target_link_libraries(fl2k_garage libgetopt_static)
-target_link_libraries(fl2k_am libgetopt_static)
+target_link_libraries(fl2k_iq libgetopt_static)
set_property(TARGET fl2k_file APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
set_property(TARGET fl2k_tcp APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
set_property(TARGET fl2k_test APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
set_property(TARGET fl2k_fm APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
set_property(TARGET fl2k_garage APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
-set_property(TARGET fl2k_am APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
+set_property(TARGET fl2k_iq APPEND PROPERTY COMPILE_DEFINITIONS "libosmo-fl2k_STATIC" )
endif()
if(MINGW)
diff --git a/src/fl2k_am.c b/src/fl2k_iq.c
index de9b01e..9821d4f 100644
--- a/src/fl2k_am.c
+++ b/src/fl2k_iq.c
@@ -2,6 +2,10 @@
* osmo-fl2k, turns FL2000-based USB 3.0 to VGA adapters into
* low cost DACs
*
+ * fl2k-iq
+ * Copyright (C) 2020 by Felix Erckenbrecht <eligs@eligs.de>
+ *
+ * based on fl2k-fm code:
* Copyright (C) 2016-2018 by Steve Markgraf <steve@steve-m.de>
*
* based on FM modulator code from VGASIG:
@@ -41,6 +45,7 @@
#endif
#include <math.h>
+#include <complex.h>
#include <pthread.h>
#include "osmo-fl2k.h"
@@ -50,16 +55,16 @@
#define BUFFER_SAMPLES (1 << BUFFER_SAMPLES_SHIFT)
#define BUFFER_SAMPLES_MASK ((1 << BUFFER_SAMPLES_SHIFT)-1)
-#define AUDIO_BUF_SIZE 2048
+#define BASEBAND_BUF_SIZE 2048
fl2k_dev_t *dev = NULL;
int do_exit = 0;
-pthread_t am_thread;
+pthread_t iq_thread;
pthread_mutex_t cb_mutex;
pthread_mutex_t am_mutex;
pthread_cond_t cb_cond;
-pthread_cond_t am_cond;
+pthread_cond_t iq_cond;
FILE *file;
int8_t *txbuf = NULL;
@@ -69,24 +74,22 @@ int8_t *buf2 = NULL;
uint32_t samp_rate = 100000000;
-int carrier_freq = 1440000;
-int carrier_per_signal;
-int input_freq = 44100;
+int base_freq = 1440000;
+int rf_to_baseband_sample_ratio;
+int input_freq = 48000;
-double mod_index = 0.9;
-double *ampbuf;
-double *slopebuf;
+complex double *ampbuf;
+complex double *slopebuf;
int writepos, readpos;
void usage(void)
{
fprintf(stderr,
- "fl2k_fm, an FM modulator for FL2K VGA dongles\n\n"
+ "fl2k_iq, an IQ modulator for FL2K VGA dongles\n\n"
"Usage:"
"\t[-d device index (default: 0)]\n"
- "\t[-c carrier frequency (default: 1440 kHz)]\n"
- "\t[-m Modulation index (default: 0.9)]\n"
- "\t[-i input audio sample rate (default: 44100 Hz for mono FM)]\n"
+ "\t[-c center frequency (default: 1440 kHz)]\n"
+ "\t[-i input baseband sample rate (default: 48000 Hz)]\n"
"\t[-s samplerate in Hz (default: 100 MS/s)]\n"
"\tfilename (use '-' to read from stdin)\n\n"
);
@@ -101,7 +104,7 @@ sighandler(int signum)
fprintf(stderr, "Signal caught, exiting!\n");
fl2k_stop_tx(dev);
do_exit = 1;
- pthread_cond_signal(&am_cond);
+ pthread_cond_signal(&iq_cond);
return TRUE;
}
return FALSE;
@@ -112,7 +115,7 @@ static void sighandler(int signum)
fprintf(stderr, "Signal caught, exiting!\n");
fl2k_stop_tx(dev);
do_exit = 1;
- pthread_cond_signal(&am_cond);
+ pthread_cond_signal(&iq_cond);
}
#endif
@@ -128,21 +131,26 @@ static void sighandler(int signum)
#define DDS_2PI (M_PI * 2) /* 2 * Pi */
#define DDS_3PI2 (M_PI_2 * 3) /* 3/2 * pi */
-#define SIN_TABLE_ORDER 8
-#define SIN_TABLE_SHIFT (32 - SIN_TABLE_ORDER)
-#define SIN_TABLE_LEN (1 << SIN_TABLE_ORDER)
+#define TRIG_TABLE_ORDER 8
+#define TRIG_TABLE_SHIFT (32 - TRIG_TABLE_ORDER)
+#define TRIG_TABLE_LEN (1 << TRIG_TABLE_ORDER)
#define ANG_INCR (0xffffffff / DDS_2PI)
-int16_t sine_table[SIN_TABLE_LEN];
-int sine_table_init = 0;
+struct trigonometric_table_S {
+ int initialized;
+ int16_t sine[TRIG_TABLE_LEN];
+ int16_t cosine[TRIG_TABLE_LEN];
+};
+
+static struct trigonometric_table_S trig_table = { .initialized = 0 };
typedef struct {
double sample_freq;
double freq;
unsigned long int phase;
unsigned long int phase_step;
- int32_t amplitude;
- double ampslope;
+ complex double amplitude;
+ complex double ampslope;
} dds_t;
static inline void dds_set_freq(dds_t *dds, double freq)
@@ -151,9 +159,9 @@ static inline void dds_set_freq(dds_t *dds, double freq)
dds->phase_step = (freq / dds->sample_freq) * 2 * M_PI * ANG_INCR;
}
-static inline void dds_set_amp(dds_t *dds, double amplitude, double ampslope)
+static inline void dds_set_amp(dds_t *dds, complex double amplitude, complex double ampslope)
{
- dds->amplitude = (int32_t) (amplitude * 32768.0);
+ dds->amplitude = amplitude;
dds->ampslope = ampslope;
}
@@ -167,12 +175,14 @@ dds_t dds_init(double sample_freq, double freq, double phase, double amp)
dds_set_freq(&dds, freq);
dds_set_amp(&dds, amp, 0);
/* Initialize sine table, prescaled for 16 bit signed integer */
- if (!sine_table_init) {
- double incr = 1.0 / (double)SIN_TABLE_LEN;
- for (i = 0; i < SIN_TABLE_LEN; i++)
- sine_table[i] = sin(incr * i * DDS_2PI) * 32767;
+ if (!trig_table.initialized) {
+ double incr = 1.0 / (double)TRIG_TABLE_LEN;
+ for (i = 0; i < TRIG_TABLE_LEN; i++){
+ trig_table.sine[i] = sin(incr * i * DDS_2PI) * 32767;
+ trig_table.cosine[i] = cos(incr * i * DDS_2PI) * 32767;
+ }
- sine_table_init = 1;
+ trig_table.initialized = 1;
}
return dds;
@@ -181,19 +191,21 @@ dds_t dds_init(double sample_freq, double freq, double phase, double amp)
static inline int8_t dds_real(dds_t *dds)
{
int tmp;
- int32_t amp;
+ int32_t amp_i, amp_q;
int8_t amp8;
// advance dds generator
- tmp = dds->phase >> SIN_TABLE_SHIFT;
+ tmp = dds->phase >> TRIG_TABLE_SHIFT;
dds->phase += dds->phase_step;
dds->phase &= 0xffffffff;
//amp = 255;
- amp = dds->amplitude; // 0..15
- amp = amp * sine_table[tmp]; // 0..31
- amp8 = (int8_t) (amp >> 24);
- //dds->amplitude += dds->ampslope;
+ amp_i = creal(dds->amplitude) * 32768.0; // 0..15
+ amp_q = cimag(dds->amplitude) * 32768.0;
+ amp_i = amp_i * trig_table.sine[tmp]; // 0..31
+ amp_q = amp_q * trig_table.cosine[tmp]; // 0..31
+ amp8 = (int8_t) ((amp_i + amp_q) >> 25); // 0..32 >> 25 => 0..8
+ dds->amplitude += dds->ampslope;
return amp8;
}
@@ -208,29 +220,29 @@ static inline void dds_real_buf(dds_t *dds, int8_t *buf, int count)
/* Generate the radio signal using the pre-calculated amplitude information
* in the amp buffer */
-static void *am_worker(void *arg)
+static void *iq_worker(void *arg)
{
register double freq;
register double tmp;
- dds_t carrier;
+ dds_t base_signal;
int8_t *tmp_ptr;
uint32_t len = 0;
uint32_t readlen, remaining;
int buf_prefilled = 0;
/* Prepare the oscillators */
- carrier = dds_init(samp_rate, carrier_freq, 0, 1);
+ base_signal = dds_init(samp_rate, base_freq, 0, 1);
while (!do_exit) {
- dds_set_amp(&carrier, ampbuf[readpos], slopebuf[readpos]);
+ dds_set_amp(&base_signal, ampbuf[readpos], slopebuf[readpos]);
readpos++;
readpos &= BUFFER_SAMPLES_MASK;
/* check if we reach the end of the buffer */
- if ((len + carrier_per_signal) > FL2K_BUF_LEN) {
+ if ((len + rf_to_baseband_sample_ratio) > FL2K_BUF_LEN) {
readlen = FL2K_BUF_LEN - len;
- remaining = carrier_per_signal - readlen;
- dds_real_buf(&carrier, &ambuf[len], readlen);
+ remaining = rf_to_baseband_sample_ratio - readlen;
+ dds_real_buf(&base_signal, &ambuf[len], readlen);
if (buf_prefilled) {
/* swap buffers */
@@ -240,15 +252,15 @@ static void *am_worker(void *arg)
pthread_cond_wait(&cb_cond, &cb_mutex);
}
- dds_real_buf(&carrier, ambuf, remaining);
+ dds_real_buf(&base_signal, ambuf, remaining);
len = remaining;
buf_prefilled = 1;
} else {
- dds_real_buf(&carrier, &ambuf[len], carrier_per_signal);
- len += carrier_per_signal;
+ dds_real_buf(&base_signal, &ambuf[len], rf_to_baseband_sample_ratio);
+ len += rf_to_baseband_sample_ratio;
}
- pthread_cond_signal(&am_cond);
+ pthread_cond_signal(&iq_cond);
}
pthread_exit(NULL);
@@ -270,13 +282,13 @@ static inline int writelen(int maxlen)
return r;
}
-static inline double modulate_sample_am(int lastwritepos, double lastamp, double sample)
+static inline complex double modulate_sample_iq(const int lastwritepos, const complex double lastamp, const complex double sample)
{
- double amp, slope;
+ complex double amp, slope;
- /* Calculate modulator amplitude at this point to lessen
+ /* Calculate modulator amplitudes at this point to lessen
* the calculations needed in the signal generator */
- amp = 1 - ((1+sample) * mod_index)/2;
+ amp = sample;
/* What we do here is calculate a linear "slope" from
the previous sample to this one. This is then used by
@@ -285,27 +297,27 @@ static inline double modulate_sample_am(int lastwritepos, double lastamp, double
the dds parameters. In fact this gives us a very
efficient and pretty good interpolation filter. */
slope = amp - lastamp;
- slope /= carrier_per_signal;
+ slope = slope * 1.0/ (double) rf_to_baseband_sample_ratio;
slopebuf[lastwritepos] = slope;
ampbuf[writepos] = amp;
return amp;
}
-void am_modulator()
+void iq_modulator()
{
unsigned int i;
size_t len;
double freq;
- double lastamp = 0;
- int16_t audio_buf[AUDIO_BUF_SIZE];
+ complex double lastamp = 0;
+ int16_t baseband_buf[BASEBAND_BUF_SIZE][2];
uint32_t lastwritepos = writepos;
- double sample;
+ complex double sample;
while (!do_exit) {
- len = writelen(AUDIO_BUF_SIZE);
+ len = writelen(BASEBAND_BUF_SIZE);
if (len > 1) {
- len = fread(audio_buf, 2, len, file);
+ len = fread(baseband_buf, 4, len, file);
if (len == 0){
if(ferror(file)){
@@ -314,15 +326,15 @@ void am_modulator()
}
for (i = 0; i < len; i++) {
- sample = (double) audio_buf[i] / 32768.0;
+ sample = (double) baseband_buf[i][0] / 32768.0 + I * (double) baseband_buf[i][0] / 32768.0;
/* Modulate and buffer the sample */
- lastamp = modulate_sample_am(lastwritepos, lastamp, sample);
+ lastamp = modulate_sample_iq(lastwritepos, lastamp, sample);
lastwritepos = writepos++;
writepos %= BUFFER_SAMPLES;
}
} else {
- pthread_cond_wait(&am_cond, &am_mutex);
+ pthread_cond_wait(&iq_cond, &am_mutex);
}
}
}
@@ -333,7 +345,7 @@ void fl2k_callback(fl2k_data_info_t *data_info)
if (data_info->device_error) {
fprintf(stderr, "Device error, exiting.\n");
do_exit = 1;
- pthread_cond_signal(&am_cond);
+ pthread_cond_signal(&iq_cond);
}
pthread_cond_signal(&cb_cond);
@@ -375,15 +387,12 @@ int main(int argc, char **argv)
dev_index = (uint32_t)atoi(optarg);
break;
case 'c':
- carrier_freq = (uint32_t)atof(optarg);
+ base_freq = (uint32_t)atof(optarg);
break;
case 'i':
input_freq = (uint32_t)atof(optarg);
input_freq_specified = 1;
break;
- case 'm':
- mod_index = atof(optarg);
- break;
case 's':
samp_rate = (uint32_t)atof(optarg);
break;
@@ -434,13 +443,12 @@ int main(int argc, char **argv)
writepos = 1;
fprintf(stderr, "Samplerate:\t%3.2f MHz\n", (double)samp_rate/1000000);
- fprintf(stderr, "Carrier:\t%5.0f kHz\n", (double)carrier_freq/1000);
- fprintf(stderr, "Mod Index:\t%2.1f %%\n", (double)mod_index*100);
+ fprintf(stderr, "Center frequency:\t%5.0f kHz\n", (double)base_freq/1000);
pthread_mutex_init(&cb_mutex, NULL);
pthread_mutex_init(&am_mutex, NULL);
pthread_cond_init(&cb_cond, NULL);
- pthread_cond_init(&am_cond, NULL);
+ pthread_cond_init(&iq_cond, NULL);
pthread_attr_init(&attr);
fl2k_open(&dev, (uint32_t)dev_index);
@@ -449,9 +457,9 @@ int main(int argc, char **argv)
goto out;
}
- r = pthread_create(&am_thread, &attr, am_worker, NULL);
+ r = pthread_create(&iq_thread, &attr, iq_worker, NULL);
if (r < 0) {
- fprintf(stderr, "Error spawning AM worker thread!\n");
+ fprintf(stderr, "Error spawning IQ worker thread!\n");
goto out;
}
@@ -467,7 +475,7 @@ int main(int argc, char **argv)
samp_rate = fl2k_get_sample_rate(dev);
/* Calculate needed constants */
- carrier_per_signal = samp_rate / input_freq;
+ rf_to_baseband_sample_ratio = samp_rate / input_freq;
#ifndef _WIN32
sigact.sa_handler = sighandler;
@@ -482,7 +490,7 @@ int main(int argc, char **argv)
SetConsoleCtrlHandler( (PHANDLER_ROUTINE) sighandler, TRUE );
#endif
- am_modulator();
+ iq_modulator();
out:
fl2k_close(dev);
generated by cgit v1.2.3 (git 2.39.1) at 2025-03-14 23:56:35 +0000