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-rw-r--r--src/mpt1327/dsp.c349
1 files changed, 349 insertions, 0 deletions
diff --git a/src/mpt1327/dsp.c b/src/mpt1327/dsp.c
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--- /dev/null
+++ b/src/mpt1327/dsp.c
@@ -0,0 +1,349 @@
+/* audio processing
+ *
+ * (C) 2021 by Andreas Eversberg <jolly@eversberg.eu>
+ * All Rights Reserved
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define CHAN mpt1327->sender.kanal
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <math.h>
+#include "../libsample/sample.h"
+#include "../libmobile/call.h"
+#include "../libdebug/debug.h"
+#include "../libtimer/timer.h"
+#include "mpt1327.h"
+#include "dsp.h"
+#include "message.h"
+
+#define PI M_PI
+
+/* signaling */
+#define MAX_DEVIATION 2500.0
+#define MAX_MODULATION 2550.0
+#define SPEECH_DEVIATION 1500.0 /* deviation of speech (no emphasis) */
+#define TX_PEAK_FSK (1500.0 / SPEECH_DEVIATION)
+#define BIT_RATE 1200.0
+#define BIT_ADJUST 0.1 /* how much do we adjust bit clock on frequency change */
+#define F0 1800.0
+#define F1 1200.0
+#define MAX_DISPLAY 1.4 /* something above speech level */
+
+/* carrier loss detection */
+#define MUTE_TIME 0.1 /* time to mute after loosing signal */
+
+void dsp_init(void)
+{
+}
+
+static int fsk_send_bit(void *inst);
+static void fsk_receive_bit(void *inst, int bit, double quality, double level);
+
+/* Init FSK of transceiver */
+int dsp_init_sender(mpt1327_t *mpt1327, double squelch_db)
+{
+ int rc;
+
+ PDEBUG_CHAN(DDSP, DEBUG_DEBUG, "Init DSP for Transceiver.\n");
+
+ /* init squelch */
+ squelch_init(&mpt1327->squelch, mpt1327->sender.kanal, squelch_db, MUTE_TIME, MUTE_TIME);
+
+ /* set modulation parameters */
+ sender_set_fm(&mpt1327->sender, MAX_DEVIATION, MAX_MODULATION, SPEECH_DEVIATION, MAX_DISPLAY);
+
+ PDEBUG(DDSP, DEBUG_DEBUG, "Using FSK level of %.3f (%.3f KHz deviation)\n", TX_PEAK_FSK, SPEECH_DEVIATION * TX_PEAK_FSK / 1e3);
+
+ /* init fsk */
+ if (fsk_mod_init(&mpt1327->fsk_mod, mpt1327, fsk_send_bit, mpt1327->sender.samplerate, BIT_RATE, F0, F1, TX_PEAK_FSK, 1, 0) < 0) {
+ PDEBUG_CHAN(DDSP, DEBUG_ERROR, "FSK init failed!\n");
+ return -EINVAL;
+ }
+ if (fsk_demod_init(&mpt1327->fsk_demod, mpt1327, fsk_receive_bit, mpt1327->sender.samplerate, BIT_RATE, F0, F1, BIT_ADJUST) < 0) {
+ PDEBUG_CHAN(DDSP, DEBUG_ERROR, "FSK init failed!\n");
+ return -EINVAL;
+ }
+
+ mpt1327->dmp_frame_level = display_measurements_add(&mpt1327->sender.dispmeas, "Frame Level", "%.1f %% (last)", DISPLAY_MEAS_LAST, DISPLAY_MEAS_LEFT, 0.0, 150.0, 100.0);
+ mpt1327->dmp_frame_quality = display_measurements_add(&mpt1327->sender.dispmeas, "Frame Quality", "%.1f %% (last)", DISPLAY_MEAS_LAST, DISPLAY_MEAS_LEFT, 0.0, 100.0, 100.0);
+
+ /* repeater */
+ rc = jitter_create(&mpt1327->repeater_dejitter, mpt1327->sender.samplerate / 5);
+ if (rc < 0) {
+ PDEBUG(DDSP, DEBUG_ERROR, "Failed to create and init repeater buffer!\n");
+ goto error;
+ }
+ return 0;
+
+error:
+ dsp_cleanup_sender(mpt1327);
+ return rc;
+}
+
+/* Cleanup transceiver instance. */
+void dsp_cleanup_sender(mpt1327_t *mpt1327)
+{
+ PDEBUG_CHAN(DDSP, DEBUG_DEBUG, "Cleanup DSP for Transceiver.\n");
+
+ fsk_mod_cleanup(&mpt1327->fsk_mod);
+ fsk_demod_cleanup(&mpt1327->fsk_demod);
+
+ jitter_destroy(&mpt1327->repeater_dejitter);
+}
+
+/* Check for SYNC bits, then collect data bits */
+static void fsk_receive_bit(void *inst, int bit, double quality, double level)
+{
+ mpt1327_t *mpt1327 = (mpt1327_t *)inst;
+ int i;
+
+ /* normalize FSK level */
+ level /= TX_PEAK_FSK;
+
+// printf("bit=%d quality=%.4f\n", bit, quality);
+ if (!mpt1327->rx_in_sync) {
+ mpt1327->rx_sync = (mpt1327->rx_sync << 1) | bit;
+
+ /* level and quality */
+ mpt1327->rx_level[mpt1327->rx_count & 0xff] = level;
+ mpt1327->rx_quality[mpt1327->rx_count & 0xff] = quality;
+ mpt1327->rx_count++;
+
+ /* check if sync pattern match */
+ if (mpt1327->rx_sync != mpt1327->sync_word)
+ return;
+
+ /* average level and quality */
+ level = quality = 0;
+ for (i = 0; i < 16; i++) {
+ level += mpt1327->rx_level[(mpt1327->rx_count - 1 - i) & 0xff];
+ quality += mpt1327->rx_quality[(mpt1327->rx_count - 1 - i) & 0xff];
+ }
+ level /= 16.0; quality /= 16.0;
+// printf("sync (level = %.2f, quality = %.2f\n", level, quality);
+
+ /* do not accept garbage */
+ if (quality < 0.65)
+ return;
+
+ /* rest sync register */
+ mpt1327->rx_sync = 0;
+ mpt1327->rx_in_sync = 1;
+ mpt1327->rx_count = 0;
+
+ /* mute audio from now on */
+ mpt1327->rx_mute = 1;
+
+ return;
+ }
+
+ /* read bits */
+ mpt1327->rx_bits = (mpt1327->rx_bits << 1) | (bit & 1);
+ mpt1327->rx_level[mpt1327->rx_count] = level;
+ mpt1327->rx_quality[mpt1327->rx_count] = quality;
+ if (++mpt1327->rx_count != 64)
+ return;
+
+ /* check parity */
+ if (mpt1327_checkbits(mpt1327->rx_bits, NULL) != (mpt1327->rx_bits & 0xffff)) {
+ PDEBUG(DDSP, DEBUG_NOTICE, "Received corrupt codeword or noise.\n");
+ mpt1327->rx_in_sync = 0;
+ mpt1327->rx_mute = 0;
+ return;
+ }
+
+ /* reset counter for next frame */
+ mpt1327->rx_count = 0;
+
+ /* average level and quality */
+ level = quality = 0;
+ for (i = 0; i < 64; i++) {
+ level += mpt1327->rx_level[i];
+ quality += mpt1327->rx_quality[i];
+ }
+ level /= 64.0; quality /= 64.0;
+
+ /* update measurements */
+ display_measurements_update(mpt1327->dmp_frame_level, level * 100.0, 0.0);
+ display_measurements_update(mpt1327->dmp_frame_quality, quality * 100.0, 0.0);
+
+ /* convert level so that received level at TX_PEAK_FSK results in 1.0 (100%) */
+ mpt1327_receive_codeword(mpt1327, mpt1327->rx_bits, quality, level);
+}
+
+/* Process received audio stream from radio unit. */
+void sender_receive(sender_t *sender, sample_t *samples, int length, double __attribute__((unused)) rf_level_db)
+{
+ mpt1327_t *mpt1327 = (mpt1327_t *) sender;
+ sample_t *spl;
+ int pos;
+ int i;
+ int was_mute = mpt1327->rx_mute; /* remember, so always mute whole chunk */
+ int was_pressel_on = mpt1327->pressel_on;
+
+ /* if channel is off, do nothing */
+ if (mpt1327->dsp_mode == DSP_MODE_OFF) {
+ /* measure squelch even if channel is turned off */
+ if (!isinf(mpt1327->squelch.threshold_db))
+ squelch(&mpt1327->squelch, rf_level_db, (double)length / (double)mpt1327->sender.samplerate);
+ return;
+ }
+
+ /* fsk signal */
+ fsk_demod_receive(&mpt1327->fsk_demod, samples, length);
+
+ /* on traffic channel mute and indicate signal strength */
+ if (mpt1327->dsp_mode == DSP_MODE_TRAFFIC) {
+ /* process signal mute/loss, also for signalling tone */
+ if (!isinf(mpt1327->squelch.threshold_db)) {
+ /* use squelch to unmute and reset call timer */
+ switch (squelch(&mpt1327->squelch, rf_level_db, (double)length / (double)mpt1327->sender.samplerate)) {
+ case SQUELCH_LOSS:
+ case SQUELCH_MUTE:
+ memset(samples, 0, sizeof(*samples) * length);
+ break;
+ default:
+ mpt1327_signal_indication(mpt1327);
+ }
+ } else {
+ /* muting audio while pressel is off */
+ if (!was_pressel_on || !mpt1327->pressel_on)
+ memset(samples, 0, sizeof(*samples) * length);
+ }
+ /* muting audio while receiving frame */
+ if (was_mute || mpt1327->rx_mute)
+ memset(samples, 0, sizeof(*samples) * length);
+ }
+
+ if (mpt1327->dsp_mode == DSP_MODE_TRAFFIC) {
+ /* if repeater mode, store sample in jitter buffer */
+ if (mpt1327->repeater)
+ jitter_save(&mpt1327->repeater_dejitter, samples, length);
+
+ if (mpt1327->unit && mpt1327->unit->callref) {
+ int count;
+
+ count = samplerate_downsample(&mpt1327->sender.srstate, samples, length);
+ spl = mpt1327->sender.rxbuf;
+ pos = mpt1327->sender.rxbuf_pos;
+ for (i = 0; i < count; i++) {
+ spl[pos++] = samples[i];
+ if (pos == 160) {
+ call_up_audio(mpt1327->unit->callref, spl, 160);
+ pos = 0;
+ }
+ }
+ mpt1327->sender.rxbuf_pos = pos;
+ } else
+ mpt1327->sender.rxbuf_pos = 0;
+ } else
+ mpt1327->sender.rxbuf_pos = 0;
+}
+
+static int fsk_send_bit(void *inst)
+{
+ mpt1327_t *mpt1327 = (mpt1327_t *)inst;
+
+ /* send frame bit (prio) */
+ if (!mpt1327->tx_bit_num || mpt1327->tx_count == mpt1327->tx_bit_num) {
+ /* request frame */
+ mpt1327->tx_bit_num = mpt1327_send_codeword(mpt1327, &mpt1327->tx_bits);
+ if (mpt1327->tx_bit_num == 0) {
+ return -1;
+ }
+ mpt1327->tx_count = 0;
+ }
+ return (mpt1327->tx_bits >> (63 - mpt1327->tx_count++)) & 1;
+
+ return -1;
+}
+
+/* Provide stream of audio toward radio unit */
+void sender_send(sender_t *sender, sample_t *samples, uint8_t *power, int length)
+{
+ mpt1327_t *mpt1327 = (mpt1327_t *) sender;
+
+ if (mpt1327->dsp_mode == DSP_MODE_OFF) {
+ memset(power, 0, length);
+ memset(samples, 0, sizeof(*samples) * length);
+ return;
+ }
+
+ memset(power, 1, length);
+
+ if (mpt1327->dsp_mode == DSP_MODE_TRAFFIC) {
+ jitter_load(&mpt1327->sender.dejitter, samples, length);
+ /* if repeater mode, sum samples from jitter buffer to samples */
+ if (mpt1327->repeater) {
+ sample_t uplink[length];
+ int i;
+ jitter_load(&mpt1327->repeater_dejitter, uplink, length);
+ for (i = 0; i < length; i++)
+ samples[i] += uplink[i];
+ }
+ } else
+ memset(samples, 0, sizeof(*samples) * length);
+
+ /* If there is something to modulate (pending TX frame),
+ * overwrite audio with FSK audio. */
+ fsk_mod_send(&mpt1327->fsk_mod, samples, length, 0);
+}
+
+const char *mpt1327_dsp_mode_name(enum dsp_mode mode)
+{
+ static char invalid[16];
+
+ switch (mode) {
+ case DSP_MODE_OFF:
+ return "OFF";
+ case DSP_MODE_TRAFFIC:
+ return "TRAFFIC";
+ case DSP_MODE_CONTROL:
+ return "CONTROL";
+ }
+
+ sprintf(invalid, "invalid(%d)", mode);
+ return invalid;
+}
+
+void mpt1327_set_dsp_mode(mpt1327_t *mpt1327, enum dsp_mode mode, int repeater)
+{
+ //NOTE: DO NOT RESET FRAME, because mode may change before frame has been sent!
+
+ if (mode == DSP_MODE_CONTROL)
+ mpt1327->sync_word = 0xc4d7;
+ if (mode == DSP_MODE_TRAFFIC)
+ mpt1327->sync_word = 0x3b28;
+
+ if (repeater)
+ jitter_reset(&mpt1327->repeater_dejitter);
+ mpt1327->repeater = repeater;
+
+ PDEBUG_CHAN(DDSP, DEBUG_DEBUG, "DSP mode %s -> %s\n", mpt1327_dsp_mode_name(mpt1327->dsp_mode), mpt1327_dsp_mode_name(mode));
+ mpt1327->dsp_mode = mode;
+}
+
+void mpt1327_reset_sync(mpt1327_t *mpt1327)
+{
+ mpt1327->rx_in_sync = 0;
+ mpt1327->rx_sync = 0;
+ mpt1327->rx_mute = 0;
+}
+