rtl-sdr: gain setting: better error messages, add some delay

fix some corner cases
wiedehopf · Apr 30, 2024 · 346e6c3 · 346e6c3
1 parent 17f089c
commit 346e6c3
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Showing 4 changed files with 53 additions and 9 deletions.
diff --git a/readsb.c b/readsb.c
@@ -250,6 +250,7 @@ static void modesInit(void) {
 
     pthread_mutex_init(&Modes.traceDebugMutex, NULL);
     pthread_mutex_init(&Modes.hungTimerMutex, NULL);
+    pthread_mutex_init(&Modes.sdrControlMutex, NULL);
 
     threadInit(&Threads.reader, "reader");
     threadInit(&Threads.upkeep, "upkeep");
@@ -2887,6 +2888,7 @@ int main(int argc, char **argv) {
 
     pthread_mutex_destroy(&Modes.traceDebugMutex);
     pthread_mutex_destroy(&Modes.hungTimerMutex);
+    pthread_mutex_destroy(&Modes.sdrControlMutex);
 
     if (Modes.debug_bogus) {
         display_total_short_range_stats();

diff --git a/readsb.h b/readsb.h
@@ -527,6 +527,8 @@ struct _Modes
     iq_convert_fn converter_function;
     char * dev_name;
     int gain;
+    int sdrInitialized;
+    pthread_mutex_t sdrControlMutex;
     int dc_filter; // should we apply a DC filter?
     int enable_agc;
     sdr_type_t sdr_type; // where are we getting data from?

diff --git a/sdr.c b/sdr.c
@@ -175,7 +175,13 @@ static sdr_handler *current_handler() {
 //
 
 bool sdrOpen() {
-    return current_handler()->open();
+    pthread_mutex_lock(&Modes.sdrControlMutex);
+    bool success = current_handler()->open();
+    pthread_mutex_unlock(&Modes.sdrControlMutex);
+    if (success) {
+        Modes.sdrInitialized = 1;
+    }
+    return success;
 }
 
 bool sdrHasRun() {
@@ -188,15 +194,31 @@ void sdrRun() {
 }
 
 void sdrCancel() {
+    pthread_mutex_lock(&Modes.sdrControlMutex);
+    Modes.sdrInitialized = 0;
+
     current_handler()->cancel();
+
+    pthread_mutex_unlock(&Modes.sdrControlMutex);
 }
 
 void sdrClose() {
+    pthread_mutex_lock(&Modes.sdrControlMutex);
+
+    Modes.sdrInitialized = 0;
     current_handler()->close();
+
+    pthread_mutex_unlock(&Modes.sdrControlMutex);
 }
 
 void sdrSetGain(){
-    current_handler()->setGain();
+    pthread_mutex_lock(&Modes.sdrControlMutex);
+
+    if (Modes.sdrInitialized) {
+        current_handler()->setGain();
+    }
+
+    pthread_mutex_unlock(&Modes.sdrControlMutex);
 }
 
 void lockReader() {

diff --git a/sdr_rtlsdr.c b/sdr_rtlsdr.c
@@ -72,6 +72,7 @@ static struct {
     int numgains;
     int *gains;
     int curGain;
+    int tunerAgcEnabled;
 } RTLSDR;
 
 //
@@ -87,14 +88,20 @@ void rtlsdrInitConfig() {
     RTLSDR.bounce_buffer = NULL;
     RTLSDR.numgains = 0;
     RTLSDR.gains = NULL;
+    RTLSDR.tunerAgcEnabled = 0;
 }
 
 void rtlsdrSetGain() {
     if (Modes.gain == MODES_AUTO_GAIN || Modes.gain >= 520) {
         Modes.gain = 590;
 
+        RTLSDR.tunerAgcEnabled = 1;
+
         fprintf(stderr, "rtlsdr: enabling tuner AGC\n");
-        rtlsdr_set_tuner_gain_mode(RTLSDR.dev, 0);
+        if (rtlsdr_set_tuner_gain_mode(RTLSDR.dev, 0)) {
+            fprintf(stderr, "rtlsdr: enabling tuner AGC failed\n");
+            return;
+        }
     } else {
 
         int target = (Modes.gain == MODES_MAX_GAIN ? 9999 : Modes.gain);
@@ -104,12 +111,23 @@ void rtlsdrSetGain() {
             if (closest == -1 || abs(RTLSDR.gains[i] - target) < abs(RTLSDR.gains[closest] - target))
                 closest = i;
         }
-
-        Modes.gain = RTLSDR.gains[closest];
-        rtlsdr_set_tuner_gain_mode(RTLSDR.dev, 1); // disable autogain
-        rtlsdr_set_tuner_gain(RTLSDR.dev, RTLSDR.gains[closest]);
-        fprintf(stderr, "rtlsdr: tuner gain set to %.1f dB\n",
-                rtlsdr_get_tuner_gain(RTLSDR.dev) / 10.0);
+        int newGain = RTLSDR.gains[closest];
+
+        if (RTLSDR.tunerAgcEnabled) {
+            if (rtlsdr_set_tuner_gain_mode(RTLSDR.dev, 1)) {
+                fprintf(stderr, "rtlsdr: disabling tuner AGC failed\n");
+                return;
+            }
+            RTLSDR.tunerAgcEnabled = 0;
+            usleep(1000);
+        }
+        if (rtlsdr_set_tuner_gain(RTLSDR.dev, newGain)) {
+            fprintf(stderr, "rtlsdr: setting tuner gain failed\n");
+            return;
+        } else {
+            fprintf(stderr, "rtlsdr: tuner gain set to %.1f dB\n", newGain / 10.0);
+            Modes.gain = newGain;
+        }
     }
 }