From ec69b94544202f3b001753e7f6f1af859b8f10d5 Mon Sep 17 00:00:00 2001
From: Oliver Jowett <oliver.jowett@flightaware.com>
Date: Mon, 19 Jul 2021 15:44:08 +0800
Subject: [PATCH] Overhaul of /etc/default/dump1090-fa

Now we have specific config options for different features rather
than just a big list of command-line options. You can still provide
custom options via EXTRA_OPTIONS or OVERRIDE_OPTIONS.

Also adds adaptive gain settings, and a "slow cpu" setting which
can turn on cpu-reducing options automatically when a slower (armv6)
CPU is in use.
---
 debian/dump1090-fa.default | 62 ++++++++++++++++++++++++++++--------
 debian/dump1090-fa.service |  2 +-
 debian/start-dump1090-fa   | 64 ++++++++++++++++++++++++++++++++++----
 3 files changed, 108 insertions(+), 20 deletions(-)

diff --git a/debian/dump1090-fa.default b/debian/dump1090-fa.default
index 12c3e31..21bb492 100644
--- a/debian/dump1090-fa.default
+++ b/debian/dump1090-fa.default
@@ -2,20 +2,56 @@
 # This is sourced by /usr/share/dump1090-fa/start-dump1090-fa as a
 # shellscript fragment.
 
-# If you are using a PiAware sdcard image, this config file is regenerated
-# on boot based on the contents of piaware-config.txt; any changes made to this
-# file will be lost.
-
 # dump1090-fa won't automatically start unless ENABLED=yes
 ENABLED=yes
 
-RECEIVER_OPTIONS="--device-index 0 --gain -10 --ppm 0"
-DECODER_OPTIONS="--max-range 360 --fix"
-NET_OPTIONS="--net --net-heartbeat 60 --net-ro-size 1300 --net-ro-interval 0.2 --net-ri-port 0 --net-ro-port 30002 --net-sbs-port 30003 --net-bi-port 30004,30104 --net-bo-port 30005"
-JSON_OPTIONS="--json-location-accuracy 1"
+# SDR device type. Use "none" for a net-only configuration
+RECEIVER=rtlsdr
+# serial number or device index of device to use (only needed if there is more than one SDR connected)
+RECEIVER_SERIAL=
+# Initial receiver gain, in dB. If adaptive gain is enabled (see below) the actual gain
+# may change over time
+RECEIVER_GAIN=60
 
-# Use a machine-specific wisdom file if it exists
-if [ -f /etc/dump1090-fa/wisdom.local ]
-then
-  RECEIVER_OPTIONS="${RECEIVER_OPTIONS} --wisdom /etc/dump1090-fa/wisdom.local"
-fi
+# Adjust gain to try to achieve optimal dynamic range / noise floor?
+ADAPTIVE_DYNAMIC_RANGE=yes
+# Reduce gain when loud message bursts from nearby aircraft are seen?
+ADAPTIVE_BURST=no
+# Gain range to allow when changing gain, in dB (empty = no limit)
+ADAPTIVE_MIN_GAIN=
+ADAPTIVE_MAX_GAIN=
+
+# Turn on options to reduce load on slower CPUs, at the expense of slightly worse decoder performance.
+# Setting "auto" will enable these options only if the CPU appears to be a slow CPU (currently this
+# means armv6 only, e.g. Pi Zero)
+SLOW_CPU=auto
+# Local wisdom file used to select DSP implementations; uses built-in ranking if the file is missing
+WISDOM=/etc/dump1090-fa/wisdom.local
+
+# Correct CRC errors where possible
+ERROR_CORRECTION=yes
+
+# Receiver location, used for some types of position decoding. Provide the location as
+# signed decimal degrees. If not given here, dump1090 will also try to read a receiver
+# location from /var/cache/piaware/location.env (written automatically by PiAware, if installed)
+RECEIVER_LAT=
+RECEIVER_LON=
+# Maximum range, in NM. Positions more distant than this are ignored. No limit if not set.
+MAX_RANGE=360
+
+# Network ports to listen on for connections
+NET_RAW_INPUT_PORTS=
+NET_RAW_OUTPUT_PORTS=30002
+NET_SBS_OUTPUT_PORTS=30003
+NET_BEAST_INPUT_PORTS=30004,30104
+NET_BEAST_OUTPUT_PORTS=30005
+
+# Accuracy of location written to JSON output
+JSON_LOCATION_ACCURACY=1
+
+# Additional options can be added here:
+EXTRA_OPTIONS=""
+
+# If OVERRIDE_OPTIONS is set, only those options are used; all other options
+# in this config file are ignored.
+OVERRIDE_OPTIONS=""
diff --git a/debian/dump1090-fa.service b/debian/dump1090-fa.service
index f05607d..617276a 100644
--- a/debian/dump1090-fa.service
+++ b/debian/dump1090-fa.service
@@ -10,7 +10,7 @@ After=network.target
 User=dump1090
 RuntimeDirectory=dump1090-fa
 RuntimeDirectoryMode=0755
-ExecStart=/usr/share/dump1090-fa/start-dump1090-fa --write-json %t/dump1090-fa --quiet
+ExecStart=/usr/share/dump1090-fa/start-dump1090-fa --write-json %t/dump1090-fa
 SyslogIdentifier=dump1090-fa
 Type=simple
 Restart=on-failure
diff --git a/debian/start-dump1090-fa b/debian/start-dump1090-fa
index 37186fe..f8b0507 100755
--- a/debian/start-dump1090-fa
+++ b/debian/start-dump1090-fa
@@ -15,19 +15,71 @@ then
     . /var/cache/piaware/location.env
 fi
 
-if [ "x$ENABLED" != "xyes" ]
+if [ "$ENABLED" != "yes" ]
 then
     echo "dump1090-fa not enabled in /etc/default/dump1090-fa" >&2
     exit 64
 fi
 
-if [ -n "$PIAWARE_LAT" -a -n "$PIAWARE_LON" ]
+# process options
+
+is_slow_cpu() {
+    case "$SLOW_CPU" in
+        yes) return 0 ;;
+        auto)
+            case $(uname -m) in
+                armv6*) return 0 ;;
+                *) return 1 ;;
+            esac
+            ;;
+        *) return 1 ;;
+    esac
+}
+
+OPTS="--quiet"
+
+if [ "${RECEIVER:-none}" = "none" ]
 then
-    POSITION="--lat $PIAWARE_LAT --lon $PIAWARE_LON"
+    OPTS="$OPTS --device-type none"
+else
+    if [ -n "$RECEIVER" ]; then OPTS="$OPTS --device-type $RECEIVER"; fi
+    if [ -n "$RECEIVER_SERIAL" ]; then OPTS="$OPTS --device-index $RECEIVER_SERIAL"; fi
+    if [ -n "$RECEIVER_GAIN" ]; then OPTS="$OPTS --gain $RECEIVER_GAIN"; fi
+    if [ -n "$WISDOM" -a -f "$WISDOM" ]; then OPTS="$OPTS --wisdom $WISDOM"; fi
+
+    if [ "$ADAPTIVE_DYNAMIC_RANGE" = "yes" ]; then OPTS="$OPTS --adaptive-range"; fi
+    if [ "$ADAPTIVE_BURST" = "yes" ]; then OPTS="$OPTS --adaptive-burst"; fi
+    if [ -n "$ADAPTIVE_MIN_GAIN" ]; then OPTS="$OPTS --adaptive-min-gain $ADAPTIVE_MIN_GAIN"; fi
+    if [ -n "$ADAPTIVE_MAX_GAIN" ]; then OPTS="$OPTS --adaptive-max-gain $ADAPTIVE_MAX_GAIN"; fi
+
+    if is_slow_cpu
+    then
+        OPTS="$OPTS --adaptive-duty-cycle 10 --no-fix-df"
+    fi
 fi
 
-exec /usr/bin/dump1090-fa \
-     $RECEIVER_OPTIONS $DECODER_OPTIONS $NET_OPTIONS $JSON_OPTIONS $POSITION \
-     "$@"
+if [ "$ERROR_CORRECTION" = "yes" ]; then OPTS="$OPTS --fix"; fi
+
+if [ -n "$RECEIVER_LAT" -a -n "$RECEIVER_LON" ]; then
+    OPTS="$OPTS --lat $RECEIVER_LAT --lon $RECEIVER_LON"
+elif  [ -n "$PIAWARE_LAT" -a -n "$PIAWARE_LON" ]; then
+    OPTS="$OPTS --lat $PIAWARE_LAT --lon $PIAWARE_LON"
+fi
+
+if [ -n "$MAX_RANGE" ]; then OPTS="$OPTS --max-range $MAX_RANGE"; fi
+
+if [ -n "$NET_RAW_INPUT_PORTS" ]; then OPTS="$OPTS --net-ri-port $NET_RAW_INPUT_PORTS"; fi
+if [ -n "$NET_RAW_OUTPUT_PORTS" ]; then OPTS="$OPTS --net-ro-port $NET_RAW_OUTPUT_PORTS"; fi
+if [ -n "$NET_SBS_OUTPUT_PORTS" ]; then OPTS="$OPTS --net-sbs-port $NET_SBS_OUTPUT_PORTS"; fi
+if [ -n "$NET_BEAST_INPUT_PORTS" ]; then OPTS="$OPTS --net-bi-port $NET_BEAST_INPUT_PORTS"; fi
+if [ -n "$NET_BEAST_OUTPUT_PORTS" ]; then OPTS="$OPTS --net-bo-port $NET_BEAST_OUTPUT_PORTS"; fi
+
+if [ -n "$JSON_LOCATION_ACCURACY" ]; then OPTS="$OPTS --json-location-accuracy $JSON_LOCATION_ACCURACY"; fi
+
+if [ -n "$EXTRA_OPTIONS" ]; then OPTS="$OPTS $EXTRA_OPTIONS"; fi
+
+if [ -n "$OVERRIDE_OPTIONS" ]; then OPTS="$OVERRIDE_OPTIONS"; fi
+
+exec /usr/bin/dump1090-fa $OPTS "$@"
 # exec failed, do not restart
 exit 64