diff options
| -rw-r--r-- | src/fl2k_ampliphase.c | 49 |
1 files changed, 41 insertions, 8 deletions
diff --git a/src/fl2k_ampliphase.c b/src/fl2k_ampliphase.c index 5e39aa0..15b2f42 100644 --- a/src/fl2k_ampliphase.c +++ b/src/fl2k_ampliphase.c @@ -153,7 +153,8 @@ static void sighandler(int signum) #define TRIG_TABLE_SHIFT (32 - TRIG_TABLE_ORDER) #define TRIG_TABLE_LEN (1 << TRIG_TABLE_ORDER) //#define ANG_INCR (0xffffffff / DDS_2PI) -#define ANG_INCR ((float)(0x100000000)) / DDS_2PI +#define INT_2PI (0x100000000) +#define ANG_INCR ((float)INT_2PI) / DDS_2PI enum waveform_E { WF_SINE, WF_RECT }; @@ -182,6 +183,8 @@ typedef struct { complex float ampslope; } dds_t; + + static inline void dds_set_freq(dds_t *dds, float freq) { dds->freq = freq; @@ -290,7 +293,7 @@ static void *iq_worker(void *arg) while (!do_exit) { // dds_set_amp(&base_signal, ampbuf[readpos], slopebuf[readpos]); - /* phase modulate the oscillator */ + /* set phase modulation value from audio input */ dds_set_phase(&base_signal, pdbuf[readpos], pdslopebuf[readpos]); readpos++; readpos &= BUFFER_SAMPLES_MASK; @@ -299,6 +302,7 @@ static void *iq_worker(void *arg) if ((len + rf_to_baseband_sample_ratio) > FL2K_BUF_LEN) { readlen = FL2K_BUF_LEN - len; remaining = rf_to_baseband_sample_ratio - readlen; + /* generate signal, perform phase modulation on both paths */ dds_complex_buf(&base_signal, &iambuf[len], &qambuf[len],readlen); if (buf_prefilled) { @@ -332,6 +336,8 @@ static void *iq_worker(void *arg) pthread_exit(NULL); } + + static inline int writelen(int maxlen) { int rp = readpos; @@ -350,7 +356,7 @@ static inline int writelen(int maxlen) -static inline float complex modulate_sample_ampliphase(const int lastwritepos, const float lastamp, const float sample, float modulationIndex) +static inline float modulate_sample_ampliphase(const int lastwritepos, const float lastamp, const float sample, float modulationIndex) { float amp; float slope; @@ -367,15 +373,32 @@ static inline float complex modulate_sample_ampliphase(const int lastwritepos, c efficient and pretty good interpolation filter. */ slope = amp - lastamp; slope = slope * 1.0/ (float) rf_to_baseband_sample_ratio; - pdbuf[writepos] = (long int) lastamp * modulationIndex * ANG_INCR; - pdslopebuf[writepos] = (long int) slope * modulationIndex * ANG_INCR; + /* set phase-delta buf*/ + /* soll: -45° .. +45° */ + /* -1 .. 1 * 45° */ + /* -1 .. 1 * 0.25 * 2 Pi */ + /* -1 .. 1 * 0.25 * 2 Pi */ + pdbuf[writepos] = (long int) (lastamp * modulationIndex * (float) INT_2PI); + pdslopebuf[writepos] = (long int) (slope * modulationIndex * (float) INT_2PI); return amp; } + void ampliphase_modulator(enum inputType_E inputType, const float modIndex) { + /* + * upper path: +45° Carrier -> Phase-Mod +/-45° * Audio In -> Squarer -> Drive + * + * lower path: -45° Carrier -> Phase-Mod -/+45° * Audio In -> Squarer -> Drive + * + * Audio In | upper | lower | shift | carrier + * 0 | +45° | -45° | 90° | 50% + * 1 | +90° | -90° | 180° | 0% + * -1 | 0° | 0° | 0° | 100% + * + */ unsigned int i; size_t len; float freq; @@ -383,7 +406,7 @@ void ampliphase_modulator(enum inputType_E inputType, const float modIndex) int16_t baseband_buf_real[BASEBAND_BUF_SIZE]; int16_t baseband_buf_cplx[BASEBAND_BUF_SIZE][2]; uint32_t lastwritepos = writepos; - float complex sample; + float sample; while (!do_exit) { int swap = swap_iq; @@ -395,6 +418,9 @@ void ampliphase_modulator(enum inputType_E inputType, const float modIndex) /* input is -1.0 .. +1.0 (-32768 .. 32767) * transform to 0.0 .. +1.0 (0 .. 32767) * put into I part of BB + * + * AM : (1 + audio) / 2 + * ^-carrier */ baseband_buf_cplx[i][0] = baseband_buf_real[i] / 2 + INT16_MAX/2; /* Q part of BB is zero for AM */ @@ -415,7 +441,10 @@ void ampliphase_modulator(enum inputType_E inputType, const float modIndex) } for (i = 0; i < len; i++) { - sample = (float) baseband_buf_cplx[i][0+swap] / 32768.0 + I * (float) baseband_buf_cplx[i][1-swap] / 32768.0; + //sample = (float) baseband_buf_cplx[i][0+swap] / 32768.0 + I * (float) baseband_buf_cplx[i][1-swap] / 32768.0; + /* keep sample real for the moment ... complex bb to be implemented + * this is amplitude only */ + sample = (float) baseband_buf_cplx[i][0+swap] / 32768.0; /* Modulate and buffer the sample */ lastamp = modulate_sample_ampliphase(lastwritepos, lastamp, sample, modIndex); @@ -459,7 +488,7 @@ int main(int argc, char **argv) int option_index = 0; int input_freq_specified = 0; enum inputType_E input_type = INP_REAL; - float modulation_index = 1.0; + float modulation_index = 0.25; /* maximum phase modulation 0.25 * 2 * Pi -> 45° */ #ifndef _WIN32 struct sigaction sigact, sigign; @@ -503,6 +532,10 @@ int main(int argc, char **argv) exit(1); } input_type = strcasecmp(optarg, "complex") == 0 ? INP_COMPLEX : INP_REAL; + if(input_type == INP_COMPLEX){ + fprintf(stderr, "Complex baseband not yet implemented.\n"); + exit(1); + } break; case 'w': swap_iq = 1; |