From 07d8c31697952fa65d8d1597cf930fe31ca253eb Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Tue, 30 Apr 2024 19:16:17 +0200
Subject: [PATCH 1/4] autogain: make noise based logic more consistent

---
 rootfs/usr/local/bin/autogain1090 | 48 ++++++++++++++++++-------------
 1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/rootfs/usr/local/bin/autogain1090 b/rootfs/usr/local/bin/autogain1090
index 69a5b80..1cc598b 100755
--- a/rootfs/usr/local/bin/autogain1090
+++ b/rootfs/usr/local/bin/autogain1090
@@ -11,12 +11,16 @@ mkdir -p $autogain_dir
 touch $autogain_dir/strong $autogain_dir/total
 
 
-# if there are no messages received and noise is lower than this, increase gain
-low_noise=-30
-# if noise is higher than this, never increase gain
+# if noise is higher than this, reduce gain
+# this is valuable for cases of strong interference where we might not see any messages at all until the gain is lowered
 high_noise=-15
 
 
+# if noise is lower than this, increase gain
+# this is valuable for cases of unamplified SDRs combined with bad antennas and a low initial gain setting
+low_noise=-36
+
+
 #work around stupid locale stuff
 export LC_ALL=C
 
@@ -54,8 +58,8 @@ fi
 # start=$(jq '.total.start' < $stats)
 # end=$(jq '.total.end' < $stats)
 
-strong=$(jq '.total.local.strong_signals' < $stats | tee $autogain_dir/strong)
-total=$(jq '.total.local.accepted | add' < $stats | tee $autogain_dir/total)
+newstrong=$(jq '.total.local.strong_signals' < $stats)
+newtotal=$(jq '.total.local.accepted | add' < $stats)
 
 noise=$(jq '.last1min.local.noise'< $stats)
 
@@ -64,24 +68,34 @@ if [[ -z $strong ]] || [[ -z $total ]]; then
     exit 1
 fi
 
-if (( oldtotal > total )) || (( oldstrong > strong )); then
+if (( oldtotal > newtotal )) || (( oldstrong > newstrong )); then
 	oldstrong=0
 	oldtotal=0
 fi
 
-strong=$((strong - oldstrong))
-total=$((total - oldtotal))
+strong=$((newstrong - oldstrong))
+total=$((newtotal - oldtotal))
+
+if ! awk "BEGIN{ exit  ($noise > $high_noise) }"; then
+    reason="Noise high: $noise dBFS > $high_noise dBFS"
+    action=Decreasing
+fi
 
-if ! awk "BEGIN{ exit  ($total < 100) }"; then
-    if ! awk "BEGIN{ exit  ($noise < $low_noise) }"; then
-        reason="Very few messages seen and noise is $noise < $low_noise"
-        action=Increasing
-    else
+if ! awk "BEGIN{ exit  ($noise < $low_noise) }"; then
+    reason="Noise low: $noise dBFS < $low_noise dBFS"
+    action=Increasing
+else
+
+
+if [[ -z "$action" ]] && ! awk "BEGIN{ exit  ($total < 500) }"; then
         echo "The decoder hasn't been running long enough, wait a bit!"
         exit 0
     fi
 fi
 
+echo "$newstrong" > $autogain_dir/strong
+echo "$newtotal" > $autogain_dir/total
+
 if [[ $total == 0 ]]; then
     percent=0
 else
@@ -131,17 +145,11 @@ if [[ -z "$action" ]] && ! awk "BEGIN{ exit ($strong < $low) }"; then
     action=Increasing
 fi
 
-if ! awk "BEGIN{ exit ($strong > $high) }"; then
+if [[ -z "$action" ]] && ! awk "BEGIN{ exit ($strong > $high) }"; then
     reason="${strong}% messages >-3dB exceed upper boundary of ${high}%"
     action=Decreasing
 fi
 
-if ! awk "BEGIN{ exit  ($noise > $high_noise) }"; then
-    # if noise is higher than this, decrease gain
-    reason="Noise at ${noise} dBFS, decreasing gain!"
-    action=Decreasing
-fi
-
 if [[ "$action" == "Decreasing" ]]; then
     gain_index=$((gain_index-1))
 elif [[ "$action" == "Increasing" ]]; then

From cc54c2bc683608d05fb4617ce04dc76cda797a79 Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Tue, 30 Apr 2024 19:24:27 +0200
Subject: [PATCH 2/4] autogain: more cleanups

---
 rootfs/usr/local/bin/autogain1090 | 31 +++++++++++--------------------
 1 file changed, 11 insertions(+), 20 deletions(-)

diff --git a/rootfs/usr/local/bin/autogain1090 b/rootfs/usr/local/bin/autogain1090
index 1cc598b..e9ef28d 100755
--- a/rootfs/usr/local/bin/autogain1090
+++ b/rootfs/usr/local/bin/autogain1090
@@ -5,7 +5,10 @@ source /scripts/common
 
 low="${READSB_AUTOGAIN_LOW_PCT:-2.5}"
 high="${READSB_AUTOGAIN_HIGH_PCT:-6.0}"
-gain_array=(0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6 -10)
+
+# this excludes 58 / tuner agc as the step is rather big resulting in oscillations and it's rarely a big improvement to use it
+gain_array=(0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4 28.0 29.7 32.8 33.8 36.4 37.2 38.6 40.2 42.1 43.4 43.9 44.5 48.0 49.6)
+
 autogain_dir="/var/globe_history/autogain"
 mkdir -p $autogain_dir
 touch $autogain_dir/strong $autogain_dir/total
@@ -24,14 +27,7 @@ low_noise=-36
 #work around stupid locale stuff
 export LC_ALL=C
 
-APP=dump1090-fa
-if [[ -f /run/dump1090-fa/stats.json ]]; then
-    APP=dump1090-fa
-elif [[ -f /run/readsb/stats.json ]]; then
-    APP=readsb
-fi
-
-stats=/run/$APP/stats.json
+stats=/run/readsb/stats.json
 
 if [[ "$1" == "reset" ]]; then
     echo "Reset AutoGain - restarting with initial values and initialization process"
@@ -50,21 +46,14 @@ if [[ -z $oldstrong ]] || [[ -z $oldtotal ]]; then
 	oldtotal=0
 fi
 
-if ! grep -qs total $stats | grep -qs -e strong_signals $stats; then
-    echo "the decoder doesn't seem to be using an rtl-sdr device, can't help with that."
-    exit 1
-fi
-
-# start=$(jq '.total.start' < $stats)
-# end=$(jq '.total.end' < $stats)
 
 newstrong=$(jq '.total.local.strong_signals' < $stats)
 newtotal=$(jq '.total.local.accepted | add' < $stats)
 
 noise=$(jq '.last1min.local.noise'< $stats)
 
-if [[ -z $strong ]] || [[ -z $total ]]; then
-    echo "unrecognized format: $stats"
+if [[ -z $newstrong ]] || [[ -z $newtotal ]]; then
+    echo "unrecognized format or no rtl-sdr in use: $stats"
     exit 1
 fi
 
@@ -76,6 +65,8 @@ fi
 strong=$((newstrong - oldstrong))
 total=$((newtotal - oldtotal))
 
+#echo "strong: $strong total: $total noise: $noise"
+
 if ! awk "BEGIN{ exit  ($noise > $high_noise) }"; then
     reason="Noise high: $noise dBFS > $high_noise dBFS"
     action=Decreasing
@@ -158,12 +149,12 @@ fi
 
 gain="${gain_array[$gain_index]}"
 
-if [[ "$action" == "Decreasing" ]] && [[ $gain_index == 0 ]]; then
+if (( $gain_index < 0 )); then
     echo "Could have used some lower gain, but gain already at minimum! ($reason)"
     exit 0
 fi
 
-if [[ $gain == "" ]] || [[ $gain == "-10" ]]; then
+if [[ "$action" == "Increasing" ]] && [[ $gain == "" ]]; then
     echo "Could have used some more gain, but gain is already at maximum! ($reason)"
     exit 0
 fi

From fe6e8803f93a86f6d6758d27f871a887c264bfe1 Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Tue, 30 Apr 2024 20:58:06 +0200
Subject: [PATCH 3/4] shellcheck

---
 rootfs/usr/local/bin/autogain1090 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rootfs/usr/local/bin/autogain1090 b/rootfs/usr/local/bin/autogain1090
index e9ef28d..81d17d8 100755
--- a/rootfs/usr/local/bin/autogain1090
+++ b/rootfs/usr/local/bin/autogain1090
@@ -149,7 +149,7 @@ fi
 
 gain="${gain_array[$gain_index]}"
 
-if (( $gain_index < 0 )); then
+if (( gain_index < 0 )); then
     echo "Could have used some lower gain, but gain already at minimum! ($reason)"
     exit 0
 fi

From 6bf958c8dc27ac01ebf7a9a0e0a678a4b797c053 Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Wed, 1 May 2024 15:12:07 +0200
Subject: [PATCH 4/4] autogain: allow temporary suspension via lock file

---
 rootfs/usr/local/bin/autogain1090 | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/rootfs/usr/local/bin/autogain1090 b/rootfs/usr/local/bin/autogain1090
index 81d17d8..b7efe01 100755
--- a/rootfs/usr/local/bin/autogain1090
+++ b/rootfs/usr/local/bin/autogain1090
@@ -11,6 +11,12 @@ gain_array=(0.0 0.9 1.4 2.7 3.7 7.7 8.7 12.5 14.4 15.7 16.6 19.7 20.7 22.9 25.4
 
 autogain_dir="/var/globe_history/autogain"
 mkdir -p $autogain_dir
+
+if [[ -f "${autogain_dir}/suspend" ]]; then
+    # allow temporary suspending of autogain by touching this file
+    exit 0
+fi
+
 touch $autogain_dir/strong $autogain_dir/total