diff --git a/overlay/etc/udev/rules.d/99-et-sdr.rules b/overlay/etc/udev/rules.d/99-et-sdr.rules
new file mode 100644
index 0000000..e32cdfd
--- /dev/null
+++ b/overlay/etc/udev/rules.d/99-et-sdr.rules
@@ -0,0 +1,15 @@
+# Author   : Gaston Gonzalez
+# Date     : 7 June 2025
+# Purpose  : udev rules for supported SDRs
+#
+# Supported Devices
+# 1. RTL-SDR Blog v2
+#
+# Preconditions:
+# 1. SDR connected via USB cable
+#
+# Postconditions:
+# 1. /dev/et-sdr created
+
+KERNEL=="swradio0", \
+   GROUP="dialout", MODE="0660", SYMLINK+="et-sdr"
diff --git a/overlay/opt/emcomm-tools/bin/et-aircraft b/overlay/opt/emcomm-tools/bin/et-aircraft
index f5a9ee9..75234f4 100755
--- a/overlay/opt/emcomm-tools/bin/et-aircraft
+++ b/overlay/opt/emcomm-tools/bin/et-aircraft
@@ -2,21 +2,21 @@
 #
 # Author  : Gaston Gonzalez
 # Date    : 4 June 2025
-# Update  : 5 June 2025
+# Update  : 7 June 2025
 # Purpose : Wrapper script around dump1090
 #
 # Preconditions:
-# 1. RTL-SDR is connected and detected
+# 1. RTL-SDR v2 is connected and detected
 #
 # Postconditions:
 # 1. dump1099 is launched
 # 2. A map is launched
 
-# TODO: Increse size of aircraft
-# TODO: Research why RTL-SDR v4 does not work
-# TODO: Check for RTL-SDR device
 # TODO: Add a systemd user service to start dump1090
 # TODO: Use icon and add to launcher
+# TODO: Increse size of aircraft
+# TODO: Research why RTL-SDR v4 does not work
+# TODO: Test RTL-SDR v3 
 # TODO: Use local new ETC offline map engine
 
 source /opt/emcomm-tools/bin/et-common
@@ -24,6 +24,8 @@ source /opt/emcomm-tools/bin/et-common
 DUMP1090_CONF_DIR="${HOME}/.local/share/emcomm-tools/dump1090"
 DUMP1090_MAP_HTML="${DUMP1090_CONF_DIR}/gmap.html"
 
+exit-if-no-sdr
+
 if [[ ! -e ${DUMP1090_MAP_HTML} ]]; then
   et-log "Map HTML not found: ${DUMP1090_MAP_HTML}"
   notify-user "Map HTML not found: ${DUMP1090_MAP_HTML}"
@@ -54,7 +56,7 @@ fi
 CMD="dump1090 --net --net-http-port 1090"
 et-log "Starting dump1090 in ${DUMP1090_CONF_DIR} with: ${CMD}"
 
-${CMD}
+${CMD} 
 
 if [[ $? -ne 0 ]]; then
   notify-user "RTL-SDR not detected. Please connect it and retry."
diff --git a/overlay/opt/emcomm-tools/bin/et-common b/overlay/opt/emcomm-tools/bin/et-common
index d14f2f9..5ebdee5 100755
--- a/overlay/opt/emcomm-tools/bin/et-common
+++ b/overlay/opt/emcomm-tools/bin/et-common
@@ -1,9 +1,15 @@
 #!/bin/bash
 # Author  : Gaston Gonzalez
 # Date    : 1 February 2025
-# Updated : 5 June 2025
+# Updated : 7 June 2025
 # Purpose : Common environment variables and functions
 
+# Standardized device paths for supported hardware
+export ET_DEVICE_AUDIO="/dev/et-audio"
+export ET_DEVICE_CAT="/dev/et-cat"
+export ET_DEVICE_GPS="/dev/et-gps"
+export ET_DEVICE_SDR="/dev/et-sdr"
+
 export ESC="\x1B"
 export RED="${ESC}[1;31m"
 export BLUE="${ESC}[1;34m"
@@ -22,3 +28,10 @@ show-err-dialog() {
 notify-user() {
   notify-send -t 5000 --app-name="EmComm Tools" "$1"
 }
+
+exit-if-no-sdr() {
+  if [[ ! -e ${ET_DEVICE_SDR} ]]; then
+    et-log "No ${ET_DEVICE_SDR} detected."
+    exit 1
+  fi
+}