From ce8ffe795727e22ec93154a5f796a03e2b7a5a95 Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Fri, 1 Nov 2024 23:56:35 +0100
Subject: [PATCH] different autogain

---
 demod_2400.c | 25 ++++++++++++++++++-------
 readsb.c     | 23 ++++++++++++++++++-----
 readsb.h     |  2 ++
 sdr_rtlsdr.c |  4 ++--
 4 files changed, 40 insertions(+), 14 deletions(-)

diff --git a/demod_2400.c b/demod_2400.c
index bab5f3a5..496329d4 100644
--- a/demod_2400.c
+++ b/demod_2400.c
@@ -287,10 +287,15 @@ void demodulate2400(struct mag_buf *mag) {
     uint16_t *pa = m;
     uint16_t *stop = m + mlen;
 
+    uint16_t *statsProgress = m;
+
+    const uint32_t statsWindow = MODES_SHORT_MSG_SAMPLES / 2; // half a short message
     uint32_t loudSamples = 0;
     uint32_t quietSamples = 0;
-    uint32_t loudThreshold = 65400 * 8; // max 65536
-    uint32_t quietThreshold = 2000 * 8;
+    uint32_t quiet2Samples = 0;
+    uint32_t loudThreshold = 55000 * statsWindow; // max 65536
+    uint32_t quietThreshold = 800 * statsWindow;
+    uint32_t quiet2Threshold = 2 * quietThreshold;
 
     for (; pa < stop; pa++) {
         int32_t pa_mag, base_noise, ref_level;
@@ -313,12 +318,17 @@ void demodulate2400(struct mag_buf *mag) {
         // due to plenty room in the message buffer for decoding
         // we can with pa go beyond stop without a buffer overrun ...
 
-        uint32_t magSum = 0;
-        for (int i = 0; i < 8; i++) {
-            magSum += pa[i];
+        if (pa >= statsProgress) {
+            uint32_t magSum = 0;
+            for (uint32_t i = 0; i < statsWindow; i++) {
+                magSum += pa[i];
+            }
+            loudSamples += statsWindow * (magSum > loudThreshold);
+            quietSamples += statsWindow * (magSum < quietThreshold);
+            quiet2Samples += statsWindow * (magSum < quiet2Threshold);
+
+            statsProgress = pa + statsWindow;
         }
-        loudSamples += 8 * (magSum > loudThreshold);
-        quietSamples += 8 * (magSum < quietThreshold);
 
         if (pa[1] > pa[7] && pa[12] > pa[14] && pa[12] > pa[15]) { goto after_pre; }
 
@@ -494,6 +504,7 @@ void demodulate2400(struct mag_buf *mag) {
 
     mag->loudSamples = loudSamples;
     mag->quietSamples = quietSamples;
+    mag->quiet2Samples = quiet2Samples;
 
     /* update noise power */
     {
diff --git a/readsb.c b/readsb.c
index 560b4b2c..f9242f57 100644
--- a/readsb.c
+++ b/readsb.c
@@ -754,10 +754,13 @@ static void *globeBinEntryPoint(void *arg) {
 static void gainStatistics(struct mag_buf *buf) {
     static uint64_t loudSamples;
     static uint64_t quietSamples;
+    static uint64_t quiet2Samples;
     static uint64_t totalSamples;
+    static int slowRise;
 
     loudSamples += buf->loudSamples;
     quietSamples += buf->quietSamples;
+    quiet2Samples += buf->quiet2Samples;
     totalSamples += buf->length;
 
     if (totalSamples < 2 * Modes.sample_rate) {
@@ -766,27 +769,37 @@ static void gainStatistics(struct mag_buf *buf) {
 
     double loudPercent = loudSamples / (double) totalSamples * 100.0;
     double quietPercent = quietSamples / (double) totalSamples * 100.0;
+    double quiet2Percent = quiet2Samples / (double) totalSamples * 100.0;
 
     // reset
     loudSamples = 0;
     quietSamples = 0;
     totalSamples = 0;
 
-    if (!Modes.autoGain) {
+    if (0 && !Modes.autoGain) {
         // don't adjust anything
         return;
     }
 
-    if (loudPercent > 0.01 || quietPercent < 0.1) {
+    if (loudPercent > 0.05 || quiet2Percent < 0.05) {
         Modes.lowerGain = 1;
     } else if (
-            quietPercent > 30.0
+            quietPercent > 10.0
             ) {
-        Modes.increaseGain = 1;
+        if (getUptime() < 1 * MINUTES || slowRise > 10) {
+            slowRise = 0;
+            Modes.increaseGain = 1;
+        } else {
+            slowRise++;
+        }
     }
     if (Modes.increaseGain || Modes.lowerGain) {
+        if (getUptime() < 1 * MINUTES) {
+            Modes.lowerGain *= 2;
+            Modes.increaseGain *= 2;
+        }
+        fprintf(stderr, "loud: %8.4f %% quiet: %8.4f %% quiet2 %8.4f %%\n", loudPercent, quietPercent, quiet2Percent);
         sdrSetGain();
-        fprintf(stderr, "loud: %8.4f %% quiet: %8.4f %%\n", loudPercent, quietPercent);
     }
 
 }
diff --git a/readsb.h b/readsb.h
index 9fd93af5..a02e894a 100644
--- a/readsb.h
+++ b/readsb.h
@@ -458,6 +458,8 @@ struct mag_buf
     int64_t sysMicroseconds; // sysTimestamp in microseconds
     uint32_t loudSamples;
     uint32_t quietSamples;
+    uint32_t quiet2Samples;
+    uint32_t padding2;
     uint16_t *data; // Magnitude data. Starts with Modes.trailing_samples worth of overlap from the previous block
 #if defined(__arm__)
     /*padding 4 bytes*/
diff --git a/sdr_rtlsdr.c b/sdr_rtlsdr.c
index 332cc64a..5123a583 100644
--- a/sdr_rtlsdr.c
+++ b/sdr_rtlsdr.c
@@ -107,9 +107,9 @@ void rtlsdrSetGain() {
     if (Modes.increaseGain || Modes.lowerGain) {
         int closest = getClosestGainIndex(Modes.gain);
         if (Modes.increaseGain) {
-            closest++;
+            closest += Modes.increaseGain;
         } else if (Modes.lowerGain) {
-            closest--;
+            closest -= Modes.lowerGain;
         }
         if (closest >= RTLSDR.numgains) {
             closest = RTLSDR.numgains - 1;