From ca46b9c906440f57f7b3cbe20841cad4ba91ab6d Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Sat, 18 May 2024 16:39:49 -0400
Subject: [PATCH 01/20] partial mlat-gps feature commit

---
 Dockerfile                                    | 12 +++++
 .../gpsd_mlat_restart/dependencies.d/startup  |  0
 .../s6-overlay/s6-rc.d/gpsd_mlat_restart/run  |  2 +
 .../s6-overlay/s6-rc.d/gpsd_mlat_restart/type |  1 +
 .../s6-rc.d/user/contents.d/gpsd_mlat_restart |  0
 .../etc/s6-overlay/scripts/gpsd_mlat_restart  | 50 +++++++++++++++++++
 rootfs/etc/s6-overlay/scripts/mlat-client     | 12 ++---
 7 files changed, 71 insertions(+), 6 deletions(-)
 create mode 100644 rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/dependencies.d/startup
 create mode 100755 rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/run
 create mode 100644 rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/type
 create mode 100644 rootfs/etc/s6-overlay/s6-rc.d/user/contents.d/gpsd_mlat_restart
 create mode 100755 rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart

diff --git a/Dockerfile b/Dockerfile
index e2802ef..c0413b1 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,3 +1,14 @@
+FROM ghcr.io/sdr-enthusiasts/docker-baseimage:base AS build
+
+RUN set -x && \
+    apt-get update -y && \
+    apt-get install -q -o Dpkg::Options::="--force-confnew" -y \
+        git gcc && \
+    cd / && \
+    git clone --depth=1 --single-branch https://github.com/sdr-enthusiasts/docker-vesselalert.git && \
+    cd /docker-vesselalert/src && \
+    gcc -static distance.c -o distance -lm -Ofast
+
 FROM ghcr.io/sdr-enthusiasts/docker-tar1090:latest
 
 LABEL org.opencontainers.image.source = "https://github.com/sdr-enthusiasts/docker-adsb-ultrafeeder"
@@ -58,6 +69,7 @@ RUN TEMP_PACKAGES=() && \
     echo "alias nano=\"nano -l\"" >> /root/.bashrc
 
 COPY rootfs/ /
+COPY --from=build /docker-vesselalert/src/distance /usr/local/bin/distance
 
 # Add Container Version
 RUN set -x && \
diff --git a/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/dependencies.d/startup b/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/dependencies.d/startup
new file mode 100644
index 0000000..e69de29
diff --git a/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/run b/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/run
new file mode 100755
index 0000000..8fefd29
--- /dev/null
+++ b/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/run
@@ -0,0 +1,2 @@
+#!/bin/sh
+exec /etc/s6-overlay/scripts/gpsd_mlat_restart
diff --git a/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/type b/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/type
new file mode 100644
index 0000000..5883cff
--- /dev/null
+++ b/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/type
@@ -0,0 +1 @@
+longrun
diff --git a/rootfs/etc/s6-overlay/s6-rc.d/user/contents.d/gpsd_mlat_restart b/rootfs/etc/s6-overlay/s6-rc.d/user/contents.d/gpsd_mlat_restart
new file mode 100644
index 0000000..e69de29
diff --git a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
new file mode 100755
index 0000000..787256e
--- /dev/null
+++ b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
@@ -0,0 +1,50 @@
+#!/command/with-contenv bash
+# shellcheck shell=bash disable=SC2015,SC2016,SC1091,SC2001,SC2154
+
+#---------------------------------------------------------------------------------------------
+# Copyright (C) 2023-2024, Ramon F. Kolb (kx1t) and contributors
+#
+# 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 <https://www.gnu.org/licenses/>.
+#---------------------------------------------------------------------------------------------
+
+source /scripts/common
+
+# Check if GPSD_IN has been enabled
+if ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_CONFIG" && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
+    "${s6wrap[@]}" echo "GPSD not enabled - no need to check receiver location"
+    exec sleep infinity
+fi
+
+# Now wait a bit to allow GPS to establish itself
+sleep "${GPSD_INITIAL_WAIT:-300}"
+
+# Make sure that receiver.json exists; if it doesn't we need to wait for it
+while ! [[ -f /run/readsb/receiver.json ]]; do
+    sleep 1 & wait $!
+done
+
+# Get initial lat/lon/alt
+lat="$(jq -r .lat /run/readsb/receiver.json)"
+lon="$(jq -r .lon /run/readsb/receiver.json)"
+
+while :; do
+    sleep "${GPSD_CHECK_INTERVAL:30}" & wait $!
+    new_lat="$(jq -r .lat /run/readsb/receiver.json)"
+    new_lon="$(jq -r .lon /run/readsb/receiver.json)"
+    new_alt="$(jq -r .alt_m_amsl /run/readsb/receiver.json)"
+    distance="$(nice -n 20 distance "$lat" "$lon" "$new_lat" "$new_lon")"
+    if (( ${distance%%.*} > ${GPSD_MIN_DISTANCE} )); then
+        "${s6wrap[@]}" echo "Receiver moved ${distance%%.*} meters - restarting all mlat-clients"
+         pkill -f "/usr/bin/python3 /usr/bin/mlat-client" >/dev/null 2>&1
+    fi
+done
\ No newline at end of file
diff --git a/rootfs/etc/s6-overlay/scripts/mlat-client b/rootfs/etc/s6-overlay/scripts/mlat-client
index 16ed88c..68075e5 100755
--- a/rootfs/etc/s6-overlay/scripts/mlat-client
+++ b/rootfs/etc/s6-overlay/scripts/mlat-client
@@ -51,17 +51,17 @@ then
     exec sleep infinity
 fi
 
-if [[ -z "$LAT$READSB_LAT" ]]; then
-    "${s6wrap[@]}" --args echo "ERROR: READSB_LAT or LAT must be defined - MLAT will be disabled."
+if [[ -z "$LAT$READSB_LAT" ]] && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_CONFIG" && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
+    "${s6wrap[@]}" --args echo "ERROR: READSB_LAT or LAT must be defined or GPSD must be enabled - MLAT will be disabled."
     exec sleep infinity
 fi
 
-if [[ -z "$LONG$READSB_LON" ]]; then
-    "${s6wrap[@]}" --args echo "ERROR: READSB_LON or LONG must be defined - MLAT will be disabled."
+if [[ -z "$LONG$READSB_LON" ]] && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_CONFIG" && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
+    "${s6wrap[@]}" --args echo "ERROR: READSB_LON or LONG must be defined or GPSD must be enabled - MLAT will be disabled."
     exec sleep infinity
 fi
-if [[ -z "$ALT$READSB_ALT" ]]; then
-    "${s6wrap[@]}" --args echo "ERROR: READSB_ALT or ALT must be defined - MLAT will be disabled."
+if [[ -z "$ALT$READSB_ALT" ]] && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_CONFIG" && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
+    "${s6wrap[@]}" --args echo "ERROR: READSB_ALT or ALT must be defined or GPSD must be enabled - MLAT will be disabled."
     exec sleep infinity
 fi
 

From 46b072763df04690dd402df46edfe0e9a42474ed Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Thu, 23 May 2024 17:46:21 -0400
Subject: [PATCH 02/20] further updates to make GPSD work

---
 .../etc/s6-overlay/scripts/gpsd_mlat_restart  | 39 ++++++++-------
 rootfs/etc/s6-overlay/scripts/mlat-client     | 50 ++++++++++++++++---
 2 files changed, 63 insertions(+), 26 deletions(-)

diff --git a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
index 787256e..ba7ae9c 100755
--- a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
+++ b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
@@ -19,32 +19,35 @@
 
 source /scripts/common
 
-# Check if GPSD_IN has been enabled
-if ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_CONFIG" && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
-    "${s6wrap[@]}" echo "GPSD not enabled - no need to check receiver location"
-    exec sleep infinity
+# Check every 60 secs if GPSD has been enabled
+if [[ ! -f /run/readsb/gpsd.json ]] || [[ "$(jq -r .lat /run/readsb/gpsd.json)" == "null" ]]; then
+    sleep 60 & wait $!
 fi
 
-# Now wait a bit to allow GPS to establish itself
-sleep "${GPSD_INITIAL_WAIT:-300}"
-
-# Make sure that receiver.json exists; if it doesn't we need to wait for it
-while ! [[ -f /run/readsb/receiver.json ]]; do
-    sleep 1 & wait $!
+# Then wait until all mlat-client instances have started
+while [[ ! -f /run/.all_mlatclient_instances_have_started ]]; do
+    sleep 5 & wait $!
 done
 
+rm -f /run/.all_mlatclient_instances_have_started
+
+# Now wait a bit to allow GPS to establish itself
+sleep "${GPSD_INITIAL_WAIT:-60}"
+
 # Get initial lat/lon/alt
-lat="$(jq -r .lat /run/readsb/receiver.json)"
-lon="$(jq -r .lon /run/readsb/receiver.json)"
+lat="${LAT:-${READSB_LAT:-$(jq -r .lat /run/readsb/gpsd.json)}}"
+lon="${LONG:-${READSB_LON:-$(jq -r .lon /run/readsb/gpsd.json)}}"
 
 while :; do
-    sleep "${GPSD_CHECK_INTERVAL:30}" & wait $!
-    new_lat="$(jq -r .lat /run/readsb/receiver.json)"
-    new_lon="$(jq -r .lon /run/readsb/receiver.json)"
-    new_alt="$(jq -r .alt_m_amsl /run/readsb/receiver.json)"
+    new_lat="$(jq -r .lat /run/readsb/gpsd.json)"
+    new_lon="$(jq -r .lon /run/readsb/gpsd.json)"
     distance="$(nice -n 20 distance "$lat" "$lon" "$new_lat" "$new_lon")"
-    if (( ${distance%%.*} > ${GPSD_MIN_DISTANCE} )); then
+    if (( ${distance%%.*} > GPSD_MIN_DISTANCE )); then
         "${s6wrap[@]}" echo "Receiver moved ${distance%%.*} meters - restarting all mlat-clients"
-         pkill -f "/usr/bin/python3 /usr/bin/mlat-client" >/dev/null 2>&1
+        # flag to the mlat-client script that it should try to use GPS coords instead of the predefined LAT/LON
+        touch /run/.gpsd_is_active
+        # kill the mlat-client instances so they get restarted with the new GPS coords
+        pkill -f "/usr/bin/python3 /usr/bin/mlat-client" >/dev/null 2>&1
     fi
+    sleep "${GPSD_CHECK_INTERVAL:30}" & wait $!
 done
\ No newline at end of file
diff --git a/rootfs/etc/s6-overlay/scripts/mlat-client b/rootfs/etc/s6-overlay/scripts/mlat-client
index 68075e5..5763e20 100755
--- a/rootfs/etc/s6-overlay/scripts/mlat-client
+++ b/rootfs/etc/s6-overlay/scripts/mlat-client
@@ -1,5 +1,5 @@
 #!/command/with-contenv bash
-# shellcheck shell=bash disable=SC1091,SC2015,SC2016
+# shellcheck shell=bash disable=SC1091,SC2015,SC2016,SC2001
 
 #---------------------------------------------------------------------------------------------
 # Copyright (C) 2023-2024, Ramon F. Kolb (kx1t) and contributors
@@ -176,24 +176,39 @@ do
     fi
 
     # add LAT/LON/ALT to instance:
-    if [[ -n "${lat_arg}" ]]; then
-        MLAT_PARAM+=(--lat "${lat_arg}")
+    # see if we need to use GPS coords:
+    unset new_lat
+    unset new_lon
+    unset new_alt
+    if [[ -f /run/.gpsd_is_active && -f /run/readsb/receiver.json ]]; then
+        new_lat="$(jq -r .lat /run/readsb/receiver.json)"
+        new_lon="$(jq -r .lon /run/readsb/receiver.json)"
+        new_alt="$(jq -r .alt_m_amsl /run/readsb/receiver.json)"
+        if [[ "$new_lat" == "null" ]] || [[ "$new_lon" == "null" ]] || [[ "$new_alt" == "null" ]]; then 
+            unset new_lat
+            unset new_lon
+            unset new_alt
+        fi
+    fi
+
+    if [[ -n "${new_lat:-$lat_arg}" ]]; then
+        MLAT_PARAM+=(--lat "${new_lat:-$lat_arg}")
     elif [[ -n "${LAT}" ]]; then
         MLAT_PARAM+=(--lat "${LAT}")
     elif [[ -n "${READSB_LAT}" ]]; then
         MLAT_PARAM+=(--lat "${READSB_LAT}")
     fi
 
-    if [[ -n "${lon_arg}" ]]; then
-        MLAT_PARAM+=(--lon "${lon_arg}")
+    if [[ -n "${new_lon:-$lon_arg}" ]]; then
+        MLAT_PARAM+=(--lon "${new_lon:-$lon_arg}")
     elif [[ -n "${LONG}" ]]; then
         MLAT_PARAM+=(--lon "${LONG}")
     elif [[ -n "${READSB_LON}" ]]; then
         MLAT_PARAM+=(--lon "${READSB_LON}")
     fi
 
-    if [[ -n "${alt_arg}" ]]; then
-        MLAT_PARAM+=(--alt "${alt_arg}")
+    if [[ -n "${new_alt:-$alt_arg}" ]]; then
+        MLAT_PARAM+=(--alt "${new_alt:-$alt_arg}")
     elif [[ -n "${ALT}" ]]; then
         MLAT_PARAM+=(--alt "${ALT}")
     elif [[ -n "${READSB_ALT}" ]]; then
@@ -240,6 +255,7 @@ do
 done
 
 sleep 5 & wait $!
+touch /run/.all_mlatclient_instances_have_started
 
 # Now iterate over all MLAT-client instances and check if they are still running:
 while true
@@ -257,6 +273,18 @@ do
             # shellcheck disable=SC2086
             execstring="$(echo ${MLAT_CMD} ${pid_array[$mlat_pid]} | xargs)"
 
+            # If GPSD is active, then replace the lat/lon/alt params with the ones from GPSD
+            if [[ -f /run/readsb/gpsd.json ]] && [[ "$(jq -r .lat /run/readsb/gpsd.json)" != "null" ]]; then
+                new_lat="$(jq -r .lat /run/readsb/gpsd.json)"
+                new_lon="$(jq -r .lon /run/readsb/gpsd.json)"
+                new_alt="$(jq -r .altMSL /run/readsb/gpsd.json)"
+                if [[ "$new_lat" != "null" ]] && [[ "$new_lon" != "null" ]] && [[ "$new_alt" != "null" ]]; then 
+                    execstring="$(sed "s/^\(.*\s\+--lat\s\+\)[0-9.-]\+\(.*\)$/\1${new_lat}\2/g" <<< "$execstring")"
+                    execstring="$(sed "s/^\(.*\s\+--lon\s\+\)[0-9.-]\+\(.*\)$/\1${new_lon}\2/g" <<< "$execstring")"
+                    execstring="$(sed "s/^\(.*\s\+--alt\s\+\)[mft0-9.-]\+\(.*\)$/\1${new_alt}m\2/g" <<< "$execstring")"
+                fi
+            fi
+
             #shellcheck disable=SC2069,SC2086
             if [[ "${LOGLEVEL}" == "verbose" ]]; then
                 "${s6wrap[@]}" --prepend="$(basename "$0")][${servername}" --args ${execstring} &
@@ -270,5 +298,11 @@ do
             unset "pid_array[${mlat_pid}]"
         fi
     done
-    sleep 10 & wait $!
+
+    # If GPSD is running, do more frequent checks than if it's not running
+    if [[ -f /run/readsb/gpsd.json ]] && [[ "$(jq -r .lat /run/readsb/gpsd.json)" != "null" ]]; then
+        sleep 1 & wait $!
+    else
+        sleep 10 & wait $!
+    fi
 done

From 04207020703173e7dc3ba3760ab4e480a3c63bd5 Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Thu, 23 May 2024 17:47:57 -0400
Subject: [PATCH 03/20] minor addition

---
 rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
index ba7ae9c..872ddc3 100755
--- a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
+++ b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
@@ -42,7 +42,7 @@ while :; do
     new_lat="$(jq -r .lat /run/readsb/gpsd.json)"
     new_lon="$(jq -r .lon /run/readsb/gpsd.json)"
     distance="$(nice -n 20 distance "$lat" "$lon" "$new_lat" "$new_lon")"
-    if (( ${distance%%.*} > GPSD_MIN_DISTANCE )); then
+    if (( ${distance%%.*} > ${GPSD_MIN_DISTANCE:-20} )); then
         "${s6wrap[@]}" echo "Receiver moved ${distance%%.*} meters - restarting all mlat-clients"
         # flag to the mlat-client script that it should try to use GPS coords instead of the predefined LAT/LON
         touch /run/.gpsd_is_active

From 02e63838e38c8c3e965d4a057a114cb18b5eeeeb Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Thu, 23 May 2024 17:58:07 -0400
Subject: [PATCH 04/20] bug fix

---
 rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
index 872ddc3..ab32d8a 100755
--- a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
+++ b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
@@ -49,5 +49,5 @@ while :; do
         # kill the mlat-client instances so they get restarted with the new GPS coords
         pkill -f "/usr/bin/python3 /usr/bin/mlat-client" >/dev/null 2>&1
     fi
-    sleep "${GPSD_CHECK_INTERVAL:30}" & wait $!
+    sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
 done
\ No newline at end of file

From 2b8ac0b40b6a18dd23c776858da23509760fd03a Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Thu, 23 May 2024 18:00:47 -0400
Subject: [PATCH 05/20] add log verbosity

---
 rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
index ab32d8a..5ab325b 100755
--- a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
+++ b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
@@ -38,6 +38,8 @@ sleep "${GPSD_INITIAL_WAIT:-60}"
 lat="${LAT:-${READSB_LAT:-$(jq -r .lat /run/readsb/gpsd.json)}}"
 lon="${LONG:-${READSB_LON:-$(jq -r .lon /run/readsb/gpsd.json)}}"
 
+"${s6wrap[@]}" echo "GPSD is active. Your mlat-client will restart with new coordinates if you move more than ${GPSD_MIN_DISTANCE:-20} meters"
+
 while :; do
     new_lat="$(jq -r .lat /run/readsb/gpsd.json)"
     new_lon="$(jq -r .lon /run/readsb/gpsd.json)"

From 5006f66b68ed5d15bdfc9424dbe20d374a04cb13 Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Thu, 23 May 2024 18:03:48 -0400
Subject: [PATCH 06/20] typo

---
 rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
index 5ab325b..055a7cd 100755
--- a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
+++ b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
@@ -38,7 +38,7 @@ sleep "${GPSD_INITIAL_WAIT:-60}"
 lat="${LAT:-${READSB_LAT:-$(jq -r .lat /run/readsb/gpsd.json)}}"
 lon="${LONG:-${READSB_LON:-$(jq -r .lon /run/readsb/gpsd.json)}}"
 
-"${s6wrap[@]}" echo "GPSD is active. Your mlat-client will restart with new coordinates if you move more than ${GPSD_MIN_DISTANCE:-20} meters"
+"${s6wrap[@]}" echo "GPSD is active. Your mlat-client(s) will restart with new coordinates if you move more than ${GPSD_MIN_DISTANCE:-20} meters"
 
 while :; do
     new_lat="$(jq -r .lat /run/readsb/gpsd.json)"

From 67e548907d206a1e3d76790ecfa13d8e7843566d Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Thu, 23 May 2024 18:05:29 -0400
Subject: [PATCH 07/20] updates

---
 rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
index 055a7cd..bd815ef 100755
--- a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
+++ b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
@@ -46,10 +46,10 @@ while :; do
     distance="$(nice -n 20 distance "$lat" "$lon" "$new_lat" "$new_lon")"
     if (( ${distance%%.*} > ${GPSD_MIN_DISTANCE:-20} )); then
         "${s6wrap[@]}" echo "Receiver moved ${distance%%.*} meters - restarting all mlat-clients"
-        # flag to the mlat-client script that it should try to use GPS coords instead of the predefined LAT/LON
-        touch /run/.gpsd_is_active
         # kill the mlat-client instances so they get restarted with the new GPS coords
         pkill -f "/usr/bin/python3 /usr/bin/mlat-client" >/dev/null 2>&1
+        lat="$new_lat"
+        lon="$new_lon"
     fi
     sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
 done
\ No newline at end of file

From 4ac8c1aa2fbb0e95a3ceafbda55f239bc020ff32 Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Thu, 23 May 2024 18:14:28 -0400
Subject: [PATCH 08/20] fix distance so the output in in meters instead of nm

---
 Dockerfile | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Dockerfile b/Dockerfile
index c0413b1..beb9c3d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,11 +2,13 @@ FROM ghcr.io/sdr-enthusiasts/docker-baseimage:base AS build
 
 RUN set -x && \
     apt-get update -y && \
-    apt-get install -q -o Dpkg::Options::="--force-confnew" -y \
+    apt-get install -q -o Dpkg::Options::="--force-confnew" -y --no-install-recommends \
         git gcc && \
     cd / && \
     git clone --depth=1 --single-branch https://github.com/sdr-enthusiasts/docker-vesselalert.git && \
     cd /docker-vesselalert/src && \
+    # make the output in meters instead of nautical miles:
+    sed -i 's|/ 1852.0||g' distance.c && \
     gcc -static distance.c -o distance -lm -Ofast
 
 FROM ghcr.io/sdr-enthusiasts/docker-tar1090:latest

From 9a99ca9118277903b84e036507e28ddcdc7dfd6f Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Thu, 23 May 2024 18:21:21 -0400
Subject: [PATCH 09/20] add local version of distance.c

---
 Dockerfile           |  7 ++---
 downloads/distance.c | 69 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+), 5 deletions(-)
 create mode 100644 downloads/distance.c

diff --git a/Dockerfile b/Dockerfile
index beb9c3d..cb65887 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,13 +2,10 @@ FROM ghcr.io/sdr-enthusiasts/docker-baseimage:base AS build
 
 RUN set -x && \
     apt-get update -y && \
-    apt-get install -q -o Dpkg::Options::="--force-confnew" -y --no-install-recommends \
+    apt-get install -q -o Dpkg::Options::="--force-confnew" -y \
         git gcc && \
     cd / && \
-    git clone --depth=1 --single-branch https://github.com/sdr-enthusiasts/docker-vesselalert.git && \
-    cd /docker-vesselalert/src && \
-    # make the output in meters instead of nautical miles:
-    sed -i 's|/ 1852.0||g' distance.c && \
+    curl -sSL https://raw.githubusercontent.com/sdr-enthusiasts/docker-adsb-ultrafeeder/main/downloads/distance.c -o /distance.c && \
     gcc -static distance.c -o distance -lm -Ofast
 
 FROM ghcr.io/sdr-enthusiasts/docker-tar1090:latest
diff --git a/downloads/distance.c b/downloads/distance.c
new file mode 100644
index 0000000..d87c2da
--- /dev/null
+++ b/downloads/distance.c
@@ -0,0 +1,69 @@
+/*
+---------------------------------------------------------------------------------------------
+Copyright (C) 2002-2022, Chris Veness
+Adaptations Copyright (C) 2023, John Norrbin (JohnEx)
+Adaptations (C) 2023, Ramon F. Kolb (kx1t)
+
+MIT License:
+
+Permission is hereby granted, free of charge, to any person 
+obtaining a copy of this software and associated documentation
+files (the "Software"), to deal in the Software without 
+restriction, including without limitation the rights to use, 
+copy, modify, merge, publish, distribute, sublicense, and/or 
+sell copies of the Software, and to permit persons to whom the
+Software is furnished to do so, subject to the following 
+conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
+THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+---------------------------------------------------------------------------------------------
+*/
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+#define PI 3.14159265
+
+// https://www.movable-type.co.uk/scripts/latlong.html
+double distance(double lat_a, double lon_a, double lat_b, double lon_b)
+{
+
+    double lat_a_scaled = lat_a * (double)PI / 180.0;
+    double lat_b_scaled = lat_b * (double)PI / 180.0;
+    double lat_delta = (lat_b - lat_a) * (double)PI / 180.0;
+    double lon_delta = (lon_b - lon_a) * (double)PI / 180.0;
+
+    double a = sin(lat_delta / 2.0) * sin(lat_delta / 2.0) + cos(lat_a_scaled) * cos(lat_b_scaled) * sin(lon_delta / 2.0) * sin(lon_delta / 2.0);
+    double c = 2.0 * atan2(sqrt(a), sqrt(1.0 - a));
+
+    return 6372797.56085 * c;
+}
+
+
+int main(int argc, char *argv[])
+{
+    if (argc != 5)
+    {
+        printf("Usage: distance lat1 lon1 lat2 lon2\n");
+        return 1;
+    }
+
+    double lat1 = atof(argv[1]);
+    double lon1 = atof(argv[2]);
+    double lat2 = atof(argv[3]);
+    double lon2 = atof(argv[4]);
+
+    double d = distance(lat1, lon1, lat2, lon2);
+    printf("%f\n", d);
+    return 0;
+}

From 91cef40cb8876b1a5f9b90d5af7f9f8c8b7221d7 Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Thu, 23 May 2024 18:28:10 -0400
Subject: [PATCH 10/20] build fix

---
 Dockerfile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index cb65887..0f4fdcd 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -3,7 +3,7 @@ FROM ghcr.io/sdr-enthusiasts/docker-baseimage:base AS build
 RUN set -x && \
     apt-get update -y && \
     apt-get install -q -o Dpkg::Options::="--force-confnew" -y \
-        git gcc && \
+        gcc && \
     cd / && \
     curl -sSL https://raw.githubusercontent.com/sdr-enthusiasts/docker-adsb-ultrafeeder/main/downloads/distance.c -o /distance.c && \
     gcc -static distance.c -o distance -lm -Ofast
@@ -68,7 +68,7 @@ RUN TEMP_PACKAGES=() && \
     echo "alias nano=\"nano -l\"" >> /root/.bashrc
 
 COPY rootfs/ /
-COPY --from=build /docker-vesselalert/src/distance /usr/local/bin/distance
+COPY --from=build /distance /usr/local/bin/distance
 
 # Add Container Version
 RUN set -x && \

From b0fadb8682ef8ce7be3b49df14aae88722c96fb5 Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Fri, 24 May 2024 09:29:36 -0400
Subject: [PATCH 11/20] fix issue

---
 rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
index bd815ef..2e8888f 100755
--- a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
+++ b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
@@ -19,18 +19,17 @@
 
 source /scripts/common
 
-# Check every 60 secs if GPSD has been enabled
-if [[ ! -f /run/readsb/gpsd.json ]] || [[ "$(jq -r .lat /run/readsb/gpsd.json)" == "null" ]]; then
-    sleep 60 & wait $!
-fi
-
-# Then wait until all mlat-client instances have started
+# Wait until all mlat-client instances have started
 while [[ ! -f /run/.all_mlatclient_instances_have_started ]]; do
     sleep 5 & wait $!
 done
-
 rm -f /run/.all_mlatclient_instances_have_started
 
+# Check every 60 secs if GPSD has been enabled
+while [[ ! -f /run/readsb/gpsd.json ]] || [[ "$(jq -r .lat /run/readsb/gpsd.json)" == "null" ]]; do
+    sleep 60 & wait $!
+done
+
 # Now wait a bit to allow GPS to establish itself
 sleep "${GPSD_INITIAL_WAIT:-60}"
 

From a0360d933bf5f2ed1a600e5f9b3f836a3516dbbb Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Fri, 24 May 2024 09:35:54 -0400
Subject: [PATCH 12/20] updates

---
 .hadolint.yaml       |  1 +
 Dockerfile           |  4 +--
 downloads/distance.c | 69 --------------------------------------------
 3 files changed, 3 insertions(+), 71 deletions(-)
 delete mode 100644 downloads/distance.c

diff --git a/.hadolint.yaml b/.hadolint.yaml
index 0306774..5bdcc7b 100644
--- a/.hadolint.yaml
+++ b/.hadolint.yaml
@@ -4,3 +4,4 @@ ignored:
   - DL3008
   - SC3054
   - SC3044
+  - DL3015
diff --git a/Dockerfile b/Dockerfile
index 0f4fdcd..52cc723 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -5,8 +5,8 @@ RUN set -x && \
     apt-get install -q -o Dpkg::Options::="--force-confnew" -y \
         gcc && \
     cd / && \
-    curl -sSL https://raw.githubusercontent.com/sdr-enthusiasts/docker-adsb-ultrafeeder/main/downloads/distance.c -o /distance.c && \
-    gcc -static distance.c -o distance -lm -Ofast
+    curl -sSL https://raw.githubusercontent.com/sdr-enthusiasts/docker-adsb-ultrafeeder/main/downloads/distance-in-meters.c -o /distance-in-meters.c && \
+    gcc -static distance-in-meters.c -o distance -lm -Ofast
 
 FROM ghcr.io/sdr-enthusiasts/docker-tar1090:latest
 
diff --git a/downloads/distance.c b/downloads/distance.c
deleted file mode 100644
index d87c2da..0000000
--- a/downloads/distance.c
+++ /dev/null
@@ -1,69 +0,0 @@
-/*
----------------------------------------------------------------------------------------------
-Copyright (C) 2002-2022, Chris Veness
-Adaptations Copyright (C) 2023, John Norrbin (JohnEx)
-Adaptations (C) 2023, Ramon F. Kolb (kx1t)
-
-MIT License:
-
-Permission is hereby granted, free of charge, to any person 
-obtaining a copy of this software and associated documentation
-files (the "Software"), to deal in the Software without 
-restriction, including without limitation the rights to use, 
-copy, modify, merge, publish, distribute, sublicense, and/or 
-sell copies of the Software, and to permit persons to whom the
-Software is furnished to do so, subject to the following 
-conditions:
-
-The above copyright notice and this permission notice shall be
-included in all copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
-OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
-HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
-WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
-ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR
-THE USE OR OTHER DEALINGS IN THE SOFTWARE.
----------------------------------------------------------------------------------------------
-*/
-#include <stdio.h>
-#include <stdlib.h>
-#include <math.h>
-
-#define PI 3.14159265
-
-// https://www.movable-type.co.uk/scripts/latlong.html
-double distance(double lat_a, double lon_a, double lat_b, double lon_b)
-{
-
-    double lat_a_scaled = lat_a * (double)PI / 180.0;
-    double lat_b_scaled = lat_b * (double)PI / 180.0;
-    double lat_delta = (lat_b - lat_a) * (double)PI / 180.0;
-    double lon_delta = (lon_b - lon_a) * (double)PI / 180.0;
-
-    double a = sin(lat_delta / 2.0) * sin(lat_delta / 2.0) + cos(lat_a_scaled) * cos(lat_b_scaled) * sin(lon_delta / 2.0) * sin(lon_delta / 2.0);
-    double c = 2.0 * atan2(sqrt(a), sqrt(1.0 - a));
-
-    return 6372797.56085 * c;
-}
-
-
-int main(int argc, char *argv[])
-{
-    if (argc != 5)
-    {
-        printf("Usage: distance lat1 lon1 lat2 lon2\n");
-        return 1;
-    }
-
-    double lat1 = atof(argv[1]);
-    double lon1 = atof(argv[2]);
-    double lat2 = atof(argv[3]);
-    double lon2 = atof(argv[4]);
-
-    double d = distance(lat1, lon1, lat2, lon2);
-    printf("%f\n", d);
-    return 0;
-}

From c03cbdd73b5326d245c605f1c9dc24e196e8fac6 Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Fri, 24 May 2024 10:59:03 -0400
Subject: [PATCH 13/20] add `gpsd` directive to the `ULTRAFEEDER-CONFIG` param;
 update documentation

---
 README.md                                   | 61 +++++++++++++++++++++
 rootfs/scripts/interpret_ultrafeeder_config |  9 +++
 2 files changed, 70 insertions(+)

diff --git a/README.md b/README.md
index bfc00f8..a53c174 100644
--- a/README.md
+++ b/README.md
@@ -38,6 +38,9 @@
       - [Configuring the Core Temperature graphs](#configuring-the-core-temperature-graphs)
       - [Reducing Disk IO for Graphs1090](#reducing-disk-io-for-graphs1090)
     - [`timelapse1090` Configuration](#timelapse1090-configuration)
+  - [Updating your location with GPSD](#updating-your-location-with-gpsd)
+    - [Basic Installation and Configuration of your GPS hardware and `gpsd` drivers](#basic-installation-and-configuration-of-your-gps-hardware-and-gpsd-drivers)
+    - [Optional parameters regulating the restart of `mlat-client` when the location changes](#optional-parameters-regulating-the-restart-of-mlat-client-when-the-location-changes)
   - [Web Pages](#web-pages)
   - [Paths](#paths)
   - [Display of Metrix with Grafana and Prometheus/InfluxDB](#display-of-metrix-with-grafana-and-prometheusinfluxdb)
@@ -728,6 +731,64 @@ Legacy: **We recommend AGAINST enabling this feature** as it has been replaced w
 | `TIMELAPSE1090_INTERVAL` | Snapshot interval in seconds                                                                                                    | `10`    |
 | `TIMELAPSE1090_HISTORY`  | Time saved in hours                                                                                                             | `24`    |
 
+## Updating your location with GPSD
+
+This feature enables you to deploy Ultrafeeder while you are moving around. It will read your current longitude/latitude/altitude from a GPS unit that is connected to `gpsd` on your host system, and ensure that the map will show your current location. It will also restart any `mlat-client` instances once it detects that you moved from your previous location.
+
+### Basic Installation and Configuration of your GPS hardware and `gpsd` drivers
+
+The simplest way of getting this to work is to acquire a ["VK163" USB GPS "Mouse"](https://a.co/d/0D7Tj0n), similar to the one in the link. You can connect this mouse to any USB port on your machine.
+
+For this to work, you should install and configure GPSD to work on your host machine. The `DEVICES` parameter is probably correct as shown below, but you may want to double-check that data is received on that device (`cat /dev/ttyACM0`) and adjust it if needed:
+
+```bash
+sudo apt update && sudo apt install -y gpsd
+cat < EOM | sudo tee /etc/default/gpsd
+# Devices gpsd should collect to at boot time.
+# They need to be read/writeable, either by user gpsd or the group dialout.
+DEVICES="/dev/ttyACM0"
+# Other options you want to pass to gpsd
+GPSD_OPTIONS="-G"
+# Automatically hot add/remove USB GPS devices via gpsdctl
+USBAUTO="true"
+EOM
+sudo systemctl restart gpsd
+```
+
+Then, you can add the following values to `ultrafeeder` service settings in `docker-compose.yml`:
+
+```yaml
+services:
+...
+  ultrafeeder:
+    ...
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
+    ...
+    environment:
+      ULTRAFEEDER-CONFIG=
+        gpsd,host.docker.internal,2947;
+    ...
+```
+
+Finally, restart the container with `docker compose up -d`
+
+This will:
+
+- install and configure `gpsd` (`/etc/default/gpsd`) so it makes GPS data available on the default TCP port 2947 of your host system
+- configure the ultrafeeder docker container to read GPSD data
+- configure the ultrafeeder container so the hostname `host.docker.internal` always resolves to the IP address of the underlying machine (where `gpsd` is running)
+
+### Optional parameters regulating the restart of `mlat-client` when the location changes
+
+The following parameters are all optional. You don't need to set them unless you want to change the default behavior:
+
+| Environment Variable | Purpose | Default |
+| -------------------- | ------- | ------- |
+| `GPSD_INITIAL_WAIT` | The initial wait period (in seconds) for the GPS data to stabilize once the container detects that GPS data is being provided | `60` (seconds) |
+| `GPSD_MIN_DISTANCE` | Distance (in meters) that your station must move before the `mlat-client`(s) are restarted with the new latitude/longitude/altitude | `20` (meters) |
+| `GPSD_CHECK_INTERVAL` | How often the container checks for updated location information. Please don't make this shorter than 30 seconds to avoid race conditions, which may cause mlat-client to stop feeding some of the aggregators | `30` (seconds) |
+
 ## Web Pages
 
 If you have configured the container as described above, you should be able to browse to the following web pages:
diff --git a/rootfs/scripts/interpret_ultrafeeder_config b/rootfs/scripts/interpret_ultrafeeder_config
index 811783d..ce70123 100755
--- a/rootfs/scripts/interpret_ultrafeeder_config
+++ b/rootfs/scripts/interpret_ultrafeeder_config
@@ -123,6 +123,15 @@ do
             MLATHUB_CONF_ARR+=("--net-connector=${mlathub_str}")
         ;;
 
+        gpsd)
+            # add gpsd_in parameter to $READSB_CONF_ARR
+            readsb_str="${param[1]},${param[2]}"
+            if [[ -n "${param[3]}" ]] && [[ -n "${param[4]}" ]]; then
+                readsb_str="$readsb_str,${param[3]},${param[4]}"
+            fi
+            READSB_CONF_ARR+=("--net-connector=${readsb_str},gpsd_in")
+        ;;
+
         *)
             # Check if there's anything in ${ULTRAFEEDER_NET_CONNECTOR} -- if not, it's a bad config element. If yes, add it as if it were ADSB
             if [[ -z "${ULTRAFEEDER_NET_CONNECTOR}" ]]; then

From 04e7707600b12257ed22802f1c6ea213304467d3 Mon Sep 17 00:00:00 2001
From: kx1t <kx1t@amsat.org>
Date: Fri, 24 May 2024 11:14:33 -0400
Subject: [PATCH 14/20] make GPS-related restarts faster

---
 rootfs/etc/s6-overlay/scripts/mlat-client | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/rootfs/etc/s6-overlay/scripts/mlat-client b/rootfs/etc/s6-overlay/scripts/mlat-client
index 5763e20..1b4b478 100755
--- a/rootfs/etc/s6-overlay/scripts/mlat-client
+++ b/rootfs/etc/s6-overlay/scripts/mlat-client
@@ -265,7 +265,10 @@ do
         if ! kill -0 "${mlat_pid}" >/dev/null 2>&1
         then
             # it exited - let's restart:
-            sleep "${RESTARTTIMER}" & wait $!
+            if [[ ! -f /run/readsb/gpsd.json ]] || [[ "$(jq -r .lat /run/readsb/gpsd.json)" == "null" ]]; then
+                # only sleep for a bit if the restarts aren't caused by GPS movement:
+                sleep "${RESTARTTIMER}" & wait $!
+            fi
             servername="$(awk '{print $4}' <<< "${pid_array[$mlat_pid]}")"
             servername="${servername%%:*}"
 
@@ -287,6 +290,7 @@ do
 
             #shellcheck disable=SC2069,SC2086
             if [[ "${LOGLEVEL}" == "verbose" ]]; then
+                "${s6wrap[@]}" --prepend="$(basename "$0")][${servername}" --args echo "Restarting: ${execstring}"
                 "${s6wrap[@]}" --prepend="$(basename "$0")][${servername}" --args ${execstring} &
             elif [[ "${LOGLEVEL}" == "error" ]]; then
                 "${s6wrap[@]}" --ignore=stdout --prepend="$(basename "$0")][${servername}" --args ${execstring} &

From e1280accdd5d4b47674eb20213005b1c325fec16 Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Sun, 26 May 2024 20:40:46 +0200
Subject: [PATCH 15/20] move gpsd_mlat_restart into mlat-client scripting

add some wait time for receiver to be stationary
---
 .../gpsd_mlat_restart/dependencies.d/startup  |   0
 .../s6-overlay/s6-rc.d/gpsd_mlat_restart/run  |   2 -
 .../s6-overlay/s6-rc.d/gpsd_mlat_restart/type |   1 -
 .../s6-rc.d/user/contents.d/gpsd_mlat_restart |   0
 .../etc/s6-overlay/scripts/gpsd_mlat_restart  |  54 -------
 rootfs/etc/s6-overlay/scripts/mlat-client     | 139 ++++++++++++------
 rootfs/etc/s6-overlay/scripts/readsb          |   8 +
 7 files changed, 106 insertions(+), 98 deletions(-)
 delete mode 100644 rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/dependencies.d/startup
 delete mode 100755 rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/run
 delete mode 100644 rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/type
 delete mode 100644 rootfs/etc/s6-overlay/s6-rc.d/user/contents.d/gpsd_mlat_restart
 delete mode 100755 rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart

diff --git a/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/dependencies.d/startup b/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/dependencies.d/startup
deleted file mode 100644
index e69de29..0000000
diff --git a/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/run b/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/run
deleted file mode 100755
index 8fefd29..0000000
--- a/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/run
+++ /dev/null
@@ -1,2 +0,0 @@
-#!/bin/sh
-exec /etc/s6-overlay/scripts/gpsd_mlat_restart
diff --git a/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/type b/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/type
deleted file mode 100644
index 5883cff..0000000
--- a/rootfs/etc/s6-overlay/s6-rc.d/gpsd_mlat_restart/type
+++ /dev/null
@@ -1 +0,0 @@
-longrun
diff --git a/rootfs/etc/s6-overlay/s6-rc.d/user/contents.d/gpsd_mlat_restart b/rootfs/etc/s6-overlay/s6-rc.d/user/contents.d/gpsd_mlat_restart
deleted file mode 100644
index e69de29..0000000
diff --git a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart b/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
deleted file mode 100755
index 2e8888f..0000000
--- a/rootfs/etc/s6-overlay/scripts/gpsd_mlat_restart
+++ /dev/null
@@ -1,54 +0,0 @@
-#!/command/with-contenv bash
-# shellcheck shell=bash disable=SC2015,SC2016,SC1091,SC2001,SC2154
-
-#---------------------------------------------------------------------------------------------
-# Copyright (C) 2023-2024, Ramon F. Kolb (kx1t) and contributors
-#
-# 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 <https://www.gnu.org/licenses/>.
-#---------------------------------------------------------------------------------------------
-
-source /scripts/common
-
-# Wait until all mlat-client instances have started
-while [[ ! -f /run/.all_mlatclient_instances_have_started ]]; do
-    sleep 5 & wait $!
-done
-rm -f /run/.all_mlatclient_instances_have_started
-
-# Check every 60 secs if GPSD has been enabled
-while [[ ! -f /run/readsb/gpsd.json ]] || [[ "$(jq -r .lat /run/readsb/gpsd.json)" == "null" ]]; do
-    sleep 60 & wait $!
-done
-
-# Now wait a bit to allow GPS to establish itself
-sleep "${GPSD_INITIAL_WAIT:-60}"
-
-# Get initial lat/lon/alt
-lat="${LAT:-${READSB_LAT:-$(jq -r .lat /run/readsb/gpsd.json)}}"
-lon="${LONG:-${READSB_LON:-$(jq -r .lon /run/readsb/gpsd.json)}}"
-
-"${s6wrap[@]}" echo "GPSD is active. Your mlat-client(s) will restart with new coordinates if you move more than ${GPSD_MIN_DISTANCE:-20} meters"
-
-while :; do
-    new_lat="$(jq -r .lat /run/readsb/gpsd.json)"
-    new_lon="$(jq -r .lon /run/readsb/gpsd.json)"
-    distance="$(nice -n 20 distance "$lat" "$lon" "$new_lat" "$new_lon")"
-    if (( ${distance%%.*} > ${GPSD_MIN_DISTANCE:-20} )); then
-        "${s6wrap[@]}" echo "Receiver moved ${distance%%.*} meters - restarting all mlat-clients"
-        # kill the mlat-client instances so they get restarted with the new GPS coords
-        pkill -f "/usr/bin/python3 /usr/bin/mlat-client" >/dev/null 2>&1
-        lat="$new_lat"
-        lon="$new_lon"
-    fi
-    sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
-done
\ No newline at end of file
diff --git a/rootfs/etc/s6-overlay/scripts/mlat-client b/rootfs/etc/s6-overlay/scripts/mlat-client
index 1b4b478..c5788bc 100755
--- a/rootfs/etc/s6-overlay/scripts/mlat-client
+++ b/rootfs/etc/s6-overlay/scripts/mlat-client
@@ -51,18 +51,67 @@ then
     exec sleep infinity
 fi
 
-if [[ -z "$LAT$READSB_LAT" ]] && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_CONFIG" && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
-    "${s6wrap[@]}" --args echo "ERROR: READSB_LAT or LAT must be defined or GPSD must be enabled - MLAT will be disabled."
-    exec sleep infinity
-fi
+function check_gpsd() {
+    if [[ -z "$GPSD" ]] || ! [[ -f /run/readsb/gpsd.json ]]; then
+        return 1
+    fi
+    if new_lat="$(jq -r .lat /run/readsb/gpsd.json)" \
+        && [[ "$new_lat" != "null" ]] \
+        && new_lon="$(jq -r .lon /run/readsb/gpsd.json)" \
+        && [[ "$new_lon" != "null" ]] \
+        && new_alt="$(jq -r .altMSL /run/readsb/gpsd.json)" \
+        && [[ "$new_alt" != "null" ]] \
 
-if [[ -z "$LONG$READSB_LON" ]] && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_CONFIG" && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
-    "${s6wrap[@]}" --args echo "ERROR: READSB_LON or LONG must be defined or GPSD must be enabled - MLAT will be disabled."
-    exec sleep infinity
-fi
-if [[ -z "$ALT$READSB_ALT" ]] && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_CONFIG" && ! grep -qi "gpsd_in" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
-    "${s6wrap[@]}" --args echo "ERROR: READSB_ALT or ALT must be defined or GPSD must be enabled - MLAT will be disabled."
-    exec sleep infinity
+    then
+        # yay, vars are set and not null
+        if ! [[ -f "$LOCATION_PERSIST" ]]; then
+            echo "$new_lat" "$new_lon" "$new_alt" > "$LOCATION_PERSIST"
+        fi
+        return 0
+    else
+        new_lat=""
+        new_lon=""
+        new_alt=""
+        return 1
+    fi
+}
+
+if grep -qs "gpsd" <<< "$ULTRAFEEDER_CONFIG" || grep -qs "gpsd" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
+    GPSD=1
+    LOCATION_PERSIST=/var/globe_history/gpsd_last_location
+    if [[ -f "$LOCATION_PERSIST" ]] && { grep -qs "gpsd" <<< "$ULTRAFEEDER_CONFIG" || grep -qs "gpsd" <<< "$ULTRAFEEDER_NET_CONNECTOR"; }; then
+        read new_lat new_lon new_alt < "$LOCATION_PERSIST"
+        "${s6wrap[@]}" --args echo "Using last known GPSD location for startup: $new_lat,$new_lon (alt: $new_alt)"
+    else
+        # wait for gpsd to continue with startup
+        "${s6wrap[@]}" --args echo "GPSD configured, no location set, no persistent location found, waiting for gpsd to provide location data"
+        while ! check_gpsd; do
+            sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
+        done
+        "${s6wrap[@]}" --args echo "GPSD has provided location data, starting mlat-clients"
+    fi
+    # initialize "old" location for gpsd movement detection
+    old_lat="$new_lat"
+    old_lon="$new_lon"
+
+    # in seconds
+    no_movement_required=19
+    # set no_movement to a number higher than the required time of no movement
+    # this way on startup there is no bogus message printed about starting mlat-clients with a new location
+    no_movement=$(( 2 * no_movement_required ))
+else
+    if [[ -z "$LAT$READSB_LAT" ]]; then
+        "${s6wrap[@]}" --args echo "ERROR: READSB_LAT or LAT must be defined or GPSD must be enabled - MLAT will be disabled."
+        exec sleep infinity
+    fi
+    if [[ -z "$LONG$READSB_LON" ]]; then
+        "${s6wrap[@]}" --args echo "ERROR: READSB_LON or LONG must be defined or GPSD must be enabled - MLAT will be disabled."
+        exec sleep infinity
+    fi
+    if [[ -z "$ALT$READSB_ALT" ]]; then
+        "${s6wrap[@]}" --args echo "ERROR: READSB_ALT or ALT must be defined or GPSD must be enabled - MLAT will be disabled."
+        exec sleep infinity
+    fi
 fi
 
 # MLAT_CONFIG has the following format:
@@ -176,20 +225,6 @@ do
     fi
 
     # add LAT/LON/ALT to instance:
-    # see if we need to use GPS coords:
-    unset new_lat
-    unset new_lon
-    unset new_alt
-    if [[ -f /run/.gpsd_is_active && -f /run/readsb/receiver.json ]]; then
-        new_lat="$(jq -r .lat /run/readsb/receiver.json)"
-        new_lon="$(jq -r .lon /run/readsb/receiver.json)"
-        new_alt="$(jq -r .alt_m_amsl /run/readsb/receiver.json)"
-        if [[ "$new_lat" == "null" ]] || [[ "$new_lon" == "null" ]] || [[ "$new_alt" == "null" ]]; then 
-            unset new_lat
-            unset new_lon
-            unset new_alt
-        fi
-    fi
 
     if [[ -n "${new_lat:-$lat_arg}" ]]; then
         MLAT_PARAM+=(--lat "${new_lat:-$lat_arg}")
@@ -255,11 +290,43 @@ do
 done
 
 sleep 5 & wait $!
-touch /run/.all_mlatclient_instances_have_started
 
 # Now iterate over all MLAT-client instances and check if they are still running:
 while true
 do
+    if check_gpsd; then
+        distance="$(distance "$old_lat" "$old_lon" "$new_lat" "$new_lon")"
+        if (( ${distance%%.*} > ${GPSD_MIN_DISTANCE:-20} )); then
+
+            # kill the mlat-client instances so they get restarted with the new GPS coords
+            if pkill -f "/usr/bin/python3 /usr/bin/mlat-client" >/dev/null 2>&1; then
+                "${s6wrap[@]}" --args echo "Receiver moved ${distance%%.*} meters - Stopping all mlat-clients"
+            else
+                "${s6wrap[@]}" --args echo "Receiver moved ${distance%%.*} meters"
+            fi
+
+            old_lat="$new_lat"
+            old_lon="$new_lon"
+
+            # new location means the receiver has moved, sleep a bit and then check again
+            no_movement=0
+            sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
+            # as the recevier has moved, mlat-clients are not restarted until there has been no movement for some time
+            # thus we continue skipping the mlat-client restart section of the loop
+            continue
+        else
+            # no movement during the checking interval, allow mlat-clients to be restarted
+            (( no_movement += ${GPSD_CHECK_INTERVAL:-30} )) || true
+            if (( no_movement < no_movement_required )); then
+                sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
+                continue
+            elif (( no_movement / ${GPSD_CHECK_INTERVAL:-30} == no_movement_required / ${GPSD_CHECK_INTERVAL:-30} )); then
+                "${s6wrap[@]}" --args echo "Receiver stationary - starting all mlat-clients with new location"
+                echo "$new_lat" "$new_lon" "$new_alt" > "$LOCATION_PERSIST"
+            fi
+        fi
+    fi
+
     for mlat_pid in "${!pid_array[@]}"
     do
         if ! kill -0 "${mlat_pid}" >/dev/null 2>&1
@@ -277,15 +344,10 @@ do
             execstring="$(echo ${MLAT_CMD} ${pid_array[$mlat_pid]} | xargs)"
 
             # If GPSD is active, then replace the lat/lon/alt params with the ones from GPSD
-            if [[ -f /run/readsb/gpsd.json ]] && [[ "$(jq -r .lat /run/readsb/gpsd.json)" != "null" ]]; then
-                new_lat="$(jq -r .lat /run/readsb/gpsd.json)"
-                new_lon="$(jq -r .lon /run/readsb/gpsd.json)"
-                new_alt="$(jq -r .altMSL /run/readsb/gpsd.json)"
-                if [[ "$new_lat" != "null" ]] && [[ "$new_lon" != "null" ]] && [[ "$new_alt" != "null" ]]; then 
-                    execstring="$(sed "s/^\(.*\s\+--lat\s\+\)[0-9.-]\+\(.*\)$/\1${new_lat}\2/g" <<< "$execstring")"
-                    execstring="$(sed "s/^\(.*\s\+--lon\s\+\)[0-9.-]\+\(.*\)$/\1${new_lon}\2/g" <<< "$execstring")"
-                    execstring="$(sed "s/^\(.*\s\+--alt\s\+\)[mft0-9.-]\+\(.*\)$/\1${new_alt}m\2/g" <<< "$execstring")"
-                fi
+            if [[ -n new_lat ]];then
+                execstring="$(sed "s/^\(.*\s\+--lat\s\+\)[0-9.-]\+\(.*\)$/\1${new_lat}\2/g" <<< "$execstring")"
+                execstring="$(sed "s/^\(.*\s\+--lon\s\+\)[0-9.-]\+\(.*\)$/\1${new_lon}\2/g" <<< "$execstring")"
+                execstring="$(sed "s/^\(.*\s\+--alt\s\+\)[mft0-9.-]\+\(.*\)$/\1${new_alt}m\2/g" <<< "$execstring")"
             fi
 
             #shellcheck disable=SC2069,SC2086
@@ -303,10 +365,5 @@ do
         fi
     done
 
-    # If GPSD is running, do more frequent checks than if it's not running
-    if [[ -f /run/readsb/gpsd.json ]] && [[ "$(jq -r .lat /run/readsb/gpsd.json)" != "null" ]]; then
-        sleep 1 & wait $!
-    else
-        sleep 10 & wait $!
-    fi
+    sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
 done
diff --git a/rootfs/etc/s6-overlay/scripts/readsb b/rootfs/etc/s6-overlay/scripts/readsb
index 5c1841c..8536ea6 100755
--- a/rootfs/etc/s6-overlay/scripts/readsb
+++ b/rootfs/etc/s6-overlay/scripts/readsb
@@ -31,6 +31,14 @@ if ! [[ "$LOGLEVEL" =~ ^(verbose|error|none)$ ]]; then
     LOGLEVEL="verbose"
 fi
 
+LOCATION_PERSIST=/var/globe_history/gpsd_last_location
+if [[ -f "$LOCATION_PERSIST" ]] && { grep -qs "gpsd" <<< "$ULTRAFEEDER_CONFIG" || grep -qs "gpsd" <<< "$ULTRAFEEDER_NET_CONNECTOR"; }; then
+    read LAT LON ALT < "$LOCATION_PERSIST"
+    READSB_LAT=""
+    READSB_LON=""
+    READSB_ALT=""
+fi
+
 # Build the readsb command line based on options
 READSB_BIN="/usr/local/bin/readsb"
 

From 342d3fcd75c8b9bb87f6a8510330643447d49dbc Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Sun, 26 May 2024 23:26:12 +0200
Subject: [PATCH 16/20] no_movement_required default / ensure > check interval

---
 rootfs/etc/s6-overlay/scripts/mlat-client | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/rootfs/etc/s6-overlay/scripts/mlat-client b/rootfs/etc/s6-overlay/scripts/mlat-client
index c5788bc..b299078 100755
--- a/rootfs/etc/s6-overlay/scripts/mlat-client
+++ b/rootfs/etc/s6-overlay/scripts/mlat-client
@@ -95,7 +95,10 @@ if grep -qs "gpsd" <<< "$ULTRAFEEDER_CONFIG" || grep -qs "gpsd" <<< "$ULTRAFEEDE
     old_lon="$new_lon"
 
     # in seconds
-    no_movement_required=19
+    no_movement_required=90
+    if (( no_movement_required < "${GPSD_CHECK_INTERVAL:-30}" )); then
+        no_movement_required="${GPSD_CHECK_INTERVAL:-30}"
+    fi
     # set no_movement to a number higher than the required time of no movement
     # this way on startup there is no bogus message printed about starting mlat-clients with a new location
     no_movement=$(( 2 * no_movement_required ))

From 04a95b7c5ea5fa2c8328e082f9c2c173499e9b3a Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Fri, 7 Jun 2024 16:00:27 +0200
Subject: [PATCH 17/20] Dockerfile: move where distance binary is built

---
 Dockerfile | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 52cc723..4a3aa6d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,13 +1,3 @@
-FROM ghcr.io/sdr-enthusiasts/docker-baseimage:base AS build
-
-RUN set -x && \
-    apt-get update -y && \
-    apt-get install -q -o Dpkg::Options::="--force-confnew" -y \
-        gcc && \
-    cd / && \
-    curl -sSL https://raw.githubusercontent.com/sdr-enthusiasts/docker-adsb-ultrafeeder/main/downloads/distance-in-meters.c -o /distance-in-meters.c && \
-    gcc -static distance-in-meters.c -o distance -lm -Ofast
-
 FROM ghcr.io/sdr-enthusiasts/docker-tar1090:latest
 
 LABEL org.opencontainers.image.source = "https://github.com/sdr-enthusiasts/docker-adsb-ultrafeeder"
@@ -53,6 +43,10 @@ RUN TEMP_PACKAGES=() && \
     ln -s /usr/local/bin/mlat-client /usr/bin/mlat-client && \
     popd && \
     rm -rf /git && \
+    # Compile distance binary
+    curl -sSL https://raw.githubusercontent.com/sdr-enthusiasts/docker-adsb-ultrafeeder/main/downloads/distance-in-meters.c -o /distance-in-meters.c && \
+    gcc -static /distance-in-meters.c -o /usr/local/bin/distance -lm -Ofast && \
+    rm -f /distance-in-meters.c && \
     #
     # Clean up and install POST_PACKAGES:
     apt-get remove -q -y "${TEMP_PACKAGES[@]}" && \
@@ -68,7 +62,6 @@ RUN TEMP_PACKAGES=() && \
     echo "alias nano=\"nano -l\"" >> /root/.bashrc
 
 COPY rootfs/ /
-COPY --from=build /distance /usr/local/bin/distance
 
 # Add Container Version
 RUN set -x && \

From 6378d30318d3af2c498ceff70560e880687dc1b5 Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Fri, 7 Jun 2024 18:16:19 +0200
Subject: [PATCH 18/20] update readme for gpsd mlat related vars

enforce limits for gpsd mlat related vars

add readme to change gpsd.socket
---
 README.md                                 | 25 +++++++++++++----
 rootfs/etc/s6-overlay/scripts/mlat-client | 33 +++++++++++++++++------
 2 files changed, 45 insertions(+), 13 deletions(-)

diff --git a/README.md b/README.md
index a53c174..5273cfc 100644
--- a/README.md
+++ b/README.md
@@ -752,7 +752,22 @@ GPSD_OPTIONS="-G"
 # Automatically hot add/remove USB GPS devices via gpsdctl
 USBAUTO="true"
 EOM
-sudo systemctl restart gpsd
+cat < EOM | sudo tee /lib/systemd/system/gpsd.socket
+[Unit]
+Description=GPS (Global Positioning System) Daemon Sockets
+
+[Socket]
+ListenStream=/run/gpsd.sock
+ListenStream=[::]:2947
+ListenStream=0.0.0.0:2947
+SocketMode=0600
+BindIPv6Only=yes
+
+[Install]
+WantedBy=sockets.target
+EOM
+sudo systemctl daemon-reload
+sudo systemctl restart gpsd gpsd.socket
 ```
 
 Then, you can add the following values to `ultrafeeder` service settings in `docker-compose.yml`:
@@ -781,13 +796,13 @@ This will:
 
 ### Optional parameters regulating the restart of `mlat-client` when the location changes
 
-The following parameters are all optional. You don't need to set them unless you want to change the default behavior:
+The following parameters are all optional and are subject to change. You don't need to set them unless you want to change the default behavior:
 
 | Environment Variable | Purpose | Default |
 | -------------------- | ------- | ------- |
-| `GPSD_INITIAL_WAIT` | The initial wait period (in seconds) for the GPS data to stabilize once the container detects that GPS data is being provided | `60` (seconds) |
-| `GPSD_MIN_DISTANCE` | Distance (in meters) that your station must move before the `mlat-client`(s) are restarted with the new latitude/longitude/altitude | `20` (meters) |
-| `GPSD_CHECK_INTERVAL` | How often the container checks for updated location information. Please don't make this shorter than 30 seconds to avoid race conditions, which may cause mlat-client to stop feeding some of the aggregators | `30` (seconds) |
+| `GPSD_MIN_DISTANCE` | Distance (in meters) that your station must move before it's considered moving (maximum 40 meters) | `20` (meters) |
+| `GPSD_MLAT_WAIT` | The wait period (in seconds) your station must be stationary before mlat is started (minimum 90 seconds) | `90` (seconds) |
+| `GPSD_CHECK_INTERVAL` | How often the container checks for updated location information. (minimum 5 seconds) | `30` (seconds) |
 
 ## Web Pages
 
diff --git a/rootfs/etc/s6-overlay/scripts/mlat-client b/rootfs/etc/s6-overlay/scripts/mlat-client
index b299078..9ec731f 100755
--- a/rootfs/etc/s6-overlay/scripts/mlat-client
+++ b/rootfs/etc/s6-overlay/scripts/mlat-client
@@ -52,7 +52,7 @@ then
 fi
 
 function check_gpsd() {
-    if [[ -z "$GPSD" ]] || ! [[ -f /run/readsb/gpsd.json ]]; then
+    if (( GPSD == 0 )) || ! [[ -f /run/readsb/gpsd.json ]]; then
         return 1
     fi
     if new_lat="$(jq -r .lat /run/readsb/gpsd.json)" \
@@ -64,9 +64,6 @@ function check_gpsd() {
 
     then
         # yay, vars are set and not null
-        if ! [[ -f "$LOCATION_PERSIST" ]]; then
-            echo "$new_lat" "$new_lon" "$new_alt" > "$LOCATION_PERSIST"
-        fi
         return 0
     else
         new_lat=""
@@ -76,6 +73,7 @@ function check_gpsd() {
     fi
 }
 
+GPSD=0
 if grep -qs "gpsd" <<< "$ULTRAFEEDER_CONFIG" || grep -qs "gpsd" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
     GPSD=1
     LOCATION_PERSIST=/var/globe_history/gpsd_last_location
@@ -88,16 +86,32 @@ if grep -qs "gpsd" <<< "$ULTRAFEEDER_CONFIG" || grep -qs "gpsd" <<< "$ULTRAFEEDE
         while ! check_gpsd; do
             sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
         done
-        "${s6wrap[@]}" --args echo "GPSD has provided location data, starting mlat-clients"
+        "${s6wrap[@]}" --args echo "GPSD has provided location data"
     fi
     # initialize "old" location for gpsd movement detection
     old_lat="$new_lat"
     old_lon="$new_lon"
 
+    GPSD_MIN_DISTANCE="${GPSD_MIN_DISTANCE:-20}"
+    # enforce gpsd min distance is no larger than 40m
+    if (( GPSD_MIN_DISTANCE > 40 )); then
+        GPSD_MIN_DISTANCE=40
+    fi
+
+    GPSD_CHECK_INTERVAL="${GPSD_CHECK_INTERVAL:-30}"
+    if (( GPSD_CHECK_INTERVAL < 5 )); then
+        GPSD_CHECK_INTERVAL=5
+    fi
+
     # in seconds
-    no_movement_required=90
-    if (( no_movement_required < "${GPSD_CHECK_INTERVAL:-30}" )); then
-        no_movement_required="${GPSD_CHECK_INTERVAL:-30}"
+    no_movement_required=${GPSD_MLAT_WAIT:-90}
+    # enforce it to be longer than the checking interval for implementation reasons
+    if (( no_movement_required < GPSD_CHECK_INTERVAL )); then
+        no_movement_required="${GPSD_CHECK_INTERVAL}"
+    fi
+    # enforce 90 second minimum
+    if (( no_movement_required < 90 )); then
+        no_movement_required=90
     fi
     # set no_movement to a number higher than the required time of no movement
     # this way on startup there is no bogus message printed about starting mlat-clients with a new location
@@ -299,6 +313,9 @@ while true
 do
     if check_gpsd; then
         distance="$(distance "$old_lat" "$old_lon" "$new_lat" "$new_lon")"
+        if ! [[ -f "$LOCATION_PERSIST" ]]; then
+            echo "$new_lat" "$new_lon" "$new_alt" > "$LOCATION_PERSIST"
+        fi
         if (( ${distance%%.*} > ${GPSD_MIN_DISTANCE:-20} )); then
 
             # kill the mlat-client instances so they get restarted with the new GPS coords

From 372600dfb5a1e92fa5e586562fdef39a0b29552f Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Fri, 7 Jun 2024 18:30:25 +0200
Subject: [PATCH 19/20] fix mlat-client auto restart when gpsd inactive

---
 rootfs/etc/s6-overlay/scripts/mlat-client | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rootfs/etc/s6-overlay/scripts/mlat-client b/rootfs/etc/s6-overlay/scripts/mlat-client
index 9ec731f..b13fc82 100755
--- a/rootfs/etc/s6-overlay/scripts/mlat-client
+++ b/rootfs/etc/s6-overlay/scripts/mlat-client
@@ -364,7 +364,7 @@ do
             execstring="$(echo ${MLAT_CMD} ${pid_array[$mlat_pid]} | xargs)"
 
             # If GPSD is active, then replace the lat/lon/alt params with the ones from GPSD
-            if [[ -n new_lat ]];then
+            if (( GPSD == 1 )); then
                 execstring="$(sed "s/^\(.*\s\+--lat\s\+\)[0-9.-]\+\(.*\)$/\1${new_lat}\2/g" <<< "$execstring")"
                 execstring="$(sed "s/^\(.*\s\+--lon\s\+\)[0-9.-]\+\(.*\)$/\1${new_lon}\2/g" <<< "$execstring")"
                 execstring="$(sed "s/^\(.*\s\+--alt\s\+\)[mft0-9.-]\+\(.*\)$/\1${new_alt}m\2/g" <<< "$execstring")"

From 0b10463093b12e590652612003ccf1cceea1d694 Mon Sep 17 00:00:00 2001
From: Matthias Wirth <matthias.wirth@gmail.com>
Date: Fri, 7 Jun 2024 19:28:16 +0200
Subject: [PATCH 20/20] don't immediately start mlat clients when GPSD is
 configured

---
 rootfs/etc/s6-overlay/scripts/mlat-client | 46 +++++++++++++++--------
 1 file changed, 31 insertions(+), 15 deletions(-)

diff --git a/rootfs/etc/s6-overlay/scripts/mlat-client b/rootfs/etc/s6-overlay/scripts/mlat-client
index b13fc82..09eb8ae 100755
--- a/rootfs/etc/s6-overlay/scripts/mlat-client
+++ b/rootfs/etc/s6-overlay/scripts/mlat-client
@@ -77,20 +77,20 @@ GPSD=0
 if grep -qs "gpsd" <<< "$ULTRAFEEDER_CONFIG" || grep -qs "gpsd" <<< "$ULTRAFEEDER_NET_CONNECTOR"; then
     GPSD=1
     LOCATION_PERSIST=/var/globe_history/gpsd_last_location
-    if [[ -f "$LOCATION_PERSIST" ]] && { grep -qs "gpsd" <<< "$ULTRAFEEDER_CONFIG" || grep -qs "gpsd" <<< "$ULTRAFEEDER_NET_CONNECTOR"; }; then
+    if [[ -f "$LOCATION_PERSIST" ]]; then
         read new_lat new_lon new_alt < "$LOCATION_PERSIST"
-        "${s6wrap[@]}" --args echo "Using last known GPSD location for startup: $new_lat,$new_lon (alt: $new_alt)"
-    else
-        # wait for gpsd to continue with startup
-        "${s6wrap[@]}" --args echo "GPSD configured, no location set, no persistent location found, waiting for gpsd to provide location data"
-        while ! check_gpsd; do
-            sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
-        done
-        "${s6wrap[@]}" --args echo "GPSD has provided location data"
     fi
     # initialize "old" location for gpsd movement detection
-    old_lat="$new_lat"
-    old_lon="$new_lon"
+    # use zero island as starting point if location persist does not exit
+    old_lat=${new_lat:-0}
+    old_lon=${new_lon:-0}
+
+    # wait for gpsd to continue with startup
+    "${s6wrap[@]}" --args echo "GPSD configured, waiting for gpsd to provide location data"
+    while ! check_gpsd; do
+        sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
+    done
+    "${s6wrap[@]}" --args echo "GPSD has provided location data"
 
     GPSD_MIN_DISTANCE="${GPSD_MIN_DISTANCE:-20}"
     # enforce gpsd min distance is no larger than 40m
@@ -284,6 +284,12 @@ do
     # shellcheck disable=SC2048,SC2086
     execstring="$(echo ${MLAT_CMD} ${MLAT_PARAM[*]} | xargs)"
 
+    if (( GPSD == 1 )); then
+        # when GPSD is active, just write the pid array, mlat-client will be started by the gpsd checking logic later
+        # use a long random PID so that it's detected as "not running"
+        pid_array["${RANDOM}${RANDOM}${RANDOM}"]="${MLAT_PARAM[*]}"
+        continue
+    fi
 
     # stagger by 15 second so they don't all start at the same time
     sleep "${MLAT_STARTUP_STAGGER:-15}" & wait $!
@@ -311,20 +317,28 @@ sleep 5 & wait $!
 # Now iterate over all MLAT-client instances and check if they are still running:
 while true
 do
-    if check_gpsd; then
+    if (( GPSD == 1 )); then
+        if ! check_gpsd; then
+            # don't do mlat client restarts if GPSD is configured but not providing a position
+            sleep "${GPSD_CHECK_INTERVAL}" & wait $!
+            continue
+        fi
+
         distance="$(distance "$old_lat" "$old_lon" "$new_lat" "$new_lon")"
         if ! [[ -f "$LOCATION_PERSIST" ]]; then
             echo "$new_lat" "$new_lon" "$new_alt" > "$LOCATION_PERSIST"
         fi
         if (( ${distance%%.*} > ${GPSD_MIN_DISTANCE:-20} )); then
 
+            msg="Receiver moved ${distance%%.*} meters"
+
             # kill the mlat-client instances so they get restarted with the new GPS coords
             if pkill -f "/usr/bin/python3 /usr/bin/mlat-client" >/dev/null 2>&1; then
-                "${s6wrap[@]}" --args echo "Receiver moved ${distance%%.*} meters - Stopping all mlat-clients"
-            else
-                "${s6wrap[@]}" --args echo "Receiver moved ${distance%%.*} meters"
+                msg+=" - Stopping all mlat-clients"
             fi
 
+            "${s6wrap[@]}" --args echo "${msg}"
+
             old_lat="$new_lat"
             old_lon="$new_lon"
 
@@ -338,6 +352,8 @@ do
             # no movement during the checking interval, allow mlat-clients to be restarted
             (( no_movement += ${GPSD_CHECK_INTERVAL:-30} )) || true
             if (( no_movement < no_movement_required )); then
+                msg="Receiver moved less than ${GPSD_MIN_DISTANCE} meters, $(( no_movement_required - no_movement )) seconds remaining before starting mlat-clients"
+                "${s6wrap[@]}" --args echo "${msg}"
                 sleep "${GPSD_CHECK_INTERVAL:-30}" & wait $!
                 continue
             elif (( no_movement / ${GPSD_CHECK_INTERVAL:-30} == no_movement_required / ${GPSD_CHECK_INTERVAL:-30} )); then