From e53f2466b497458c5089455e9735945702a9952c Mon Sep 17 00:00:00 2001
From: Clyde McQueen <clyde@mcqueen.net>
Date: Tue, 18 Jul 2023 13:19:38 -0700
Subject: [PATCH] Ignore DISTANCE_SENSOR msgs with low signal_quality

---
 libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.cpp | 9 +++++----
 libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.h   | 1 +
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.cpp b/libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.cpp
index 5e52a9a2223bc8..16da6d5f5f2299 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.cpp
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.cpp
@@ -27,13 +27,14 @@ void AP_RangeFinder_MAVLink::handle_msg(const mavlink_message_t &msg)
     mavlink_distance_sensor_t packet;
     mavlink_msg_distance_sensor_decode(&msg, &packet);
 
-    // only accept distances for the configured orentation
+    // only accept distances for the configured orientation
     if (packet.orientation == orientation()) {
         state.last_reading_ms = AP_HAL::millis();
         distance_cm = packet.current_distance;
         _max_distance_cm = packet.max_distance;
         _min_distance_cm = packet.min_distance;
         sensor_type = (MAV_DISTANCE_SENSOR)packet.type;
+        signal_quality = packet.signal_quality;
     }
 }
 
@@ -66,9 +67,9 @@ int16_t AP_RangeFinder_MAVLink::min_distance_cm() const
 */
 void AP_RangeFinder_MAVLink::update(void)
 {
-    //Time out on incoming data; if we don't get new
-    //data in 500ms, dump it
-    if (AP_HAL::millis() - state.last_reading_ms > AP_RANGEFINDER_MAVLINK_TIMEOUT_MS) {
+    // time out on incoming data; if we don't get new data in 500ms, dump it
+    // ignore readings where signal_quality is below cutoff
+    if (AP_HAL::millis() - state.last_reading_ms > AP_RANGEFINDER_MAVLINK_TIMEOUT_MS || (signal_quality > 0 && signal_quality < 90)) {
         set_status(RangeFinder::Status::NoData);
         state.distance_m = 0.0f;
     } else {
diff --git a/libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.h b/libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.h
index b38c6fcc494750..4012d87a0be435 100644
--- a/libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.h
+++ b/libraries/AP_RangeFinder/AP_RangeFinder_MAVLink.h
@@ -43,6 +43,7 @@ class AP_RangeFinder_MAVLink : public AP_RangeFinder_Backend
     uint16_t distance_cm;
     uint16_t _max_distance_cm;
     uint16_t _min_distance_cm;
+    uint8_t signal_quality;
 
     // start a reading
     static bool start_reading(void);