Add power control to AM (power on/off per sample)

4 files changed, 10 insertions, 8 deletions

diff --git a/src/libam/am.c b/src/libam/am.c
index d5c50b6..7194b49 100644
--- a/src/libam/am.c
+++ b/src/libam/am.c
@@ -91,7 +91,7 @@ void am_mod_exit(am_mod_t __attribute__((unused)) *mod)
 {
 }
 
-void am_modulate_complex(am_mod_t *mod, sample_t *amplitude, int num, float *baseband)
+void am_modulate_complex(am_mod_t *mod, sample_t *amplitude, uint8_t *power, int num, float *baseband)
 {
 	int s;
 	double vector;
@@ -101,7 +101,10 @@ void am_modulate_complex(am_mod_t *mod, sample_t *amplitude, int num, float *bas
 	double bias = mod->bias;
 
 	for (s = 0; s < num; s++) {
-		vector = *amplitude++ * gain + bias;
+		if (*power++)
+			vector = *amplitude++ * gain + bias;
+		else
+			vector = 0.0;
 		if (fast_math) {
 			*baseband++ += cos_tab[(uint16_t)phase] * vector;
 			*baseband++ += sin_tab[(uint16_t)phase] * vector;
diff --git a/src/libam/am.h b/src/libam/am.h
index 6bebe2c..345171c 100644
--- a/src/libam/am.h
+++ b/src/libam/am.h
@@ -12,7 +12,7 @@ typedef struct am_mod {
 
 int am_mod_init(am_mod_t *mod, double samplerate, double offset, double gain, double bias);
 void am_mod_exit(am_mod_t *mod);
-void am_modulate_complex(am_mod_t *mod, sample_t *amplitude, int num, float *baseband);
+void am_modulate_complex(am_mod_t *mod, sample_t *amplitude, uint8_t *power, int num, float *baseband);
 
 typedef struct am_demod {
 	double	rot;		/* angle to rotate vector per sample */
diff --git a/src/libsdr/sdr.c b/src/libsdr/sdr.c
index eb627f2..49dea2b 100644
--- a/src/libsdr/sdr.c
+++ b/src/libsdr/sdr.c
@@ -775,8 +775,7 @@ int sdr_write(void *inst, sample_t **samples, uint8_t **power, int num, enum pag
 			if (on[c] && sdr->paging_channel)
 				fm_modulate_complex(&sdr->chan[sdr->paging_channel].fm_mod, samples[c], power[c], num, buff);
 			else if (sdr->chan[c].am) {
-				if (power[c][0])
-					am_modulate_complex(&sdr->chan[c].am_mod, samples[c], num, buff);
+				am_modulate_complex(&sdr->chan[c].am_mod, samples[c], power[c], num, buff);
 			} else
 				fm_modulate_complex(&sdr->chan[c].fm_mod, samples[c], power[c], num, buff);
 		}
diff --git a/src/radio/radio.c b/src/radio/radio.c
index c1be7e7..ead2ae1 100644
--- a/src/radio/radio.c
+++ b/src/radio/radio.c
@@ -546,12 +546,12 @@ int radio_tx(radio_t *radio, float *baseband, int signal_num)
 
 	/* prepare baseband */
 	memset(baseband, 0, sizeof(float) * 2 * signal_num);
+	memset(signal_power, 1, signal_num);
 
 	/* filter audio (remove DC, remove high frequencies, pre-emphasis)
 	 * and modulate */
 	switch (radio->modulation) {
 	case MODULATION_FM:
-		memset(signal_power, 1, signal_num);
 		pre_emphasis(&radio->fm_emphasis[0], signal_samples[0], signal_num);
 		clipper_process(signal_samples[0], signal_num);
 		if (radio->stereo) {
@@ -577,14 +577,14 @@ int radio_tx(radio_t *radio, float *baseband, int signal_num)
 		/* also clip to prevent overshooting after audio filtering */
 		clipper_process(signal_samples[0], signal_num);
 		iir_process(&radio->tx_am_bw_limit, signal_samples[0], signal_num);
-		am_modulate_complex(&radio->am_mod, signal_samples[0], signal_num, baseband);
+		am_modulate_complex(&radio->am_mod, signal_samples[0], signal_power, signal_num, baseband);
 		break;
 	case MODULATION_AM_USB:
 	case MODULATION_AM_LSB:
 		/* also clip to prevent overshooting after audio filtering */
 		clipper_process(signal_samples[0], signal_num);
 		iir_process(&radio->tx_am_bw_limit, signal_samples[0], signal_num);
-		am_modulate_complex(&radio->am_mod, signal_samples[0], signal_num, baseband);
+		am_modulate_complex(&radio->am_mod, signal_samples[0], signal_power, signal_num, baseband);
 		break;
 	default:
 		break;