Ford: filter out close high coverage range radar points (#1415)

* no functional change, but later

* check correct radar configuration

* add comments

* temp

* clean up

opendbc/car/ford/radar_interface.py

@@ -13,6 +13,7 @@
 DELPHI_MRR_RADAR_MSG_COUNT = 64
 
 DELPHI_MRR_RADAR_RANGE_COVERAGE = {0: 42, 1: 164, 2: 45, 3: 175}  # scan index to detection range (m)
+MIN_LONG_RANGE_DIST = 30  # meters
 
 
 def _create_delphi_esr_radar_can_parser(CP) -> CANParser:
@@ -138,9 +139,13 @@ def _update_delphi_mrr(self):
 
       valid = bool(msg[f"CAN_DET_VALID_LEVEL_{ii:02d}"])
 
+      # Long range measurement mode is more sensitive and can detect the road surface
+      dist = msg[f"CAN_DET_RANGE_{ii:02d}"]  # m [0|255.984]
+      if scanIndex in (1, 3) and dist < MIN_LONG_RANGE_DIST:
+        valid = False
+
       if valid:
         azimuth = msg[f"CAN_DET_AZIMUTH_{ii:02d}"]              # rad [-3.1416|3.13964]
-        dist = msg[f"CAN_DET_RANGE_{ii:02d}"]                   # m [0|255.984]
         distRate = msg[f"CAN_DET_RANGE_RATE_{ii:02d}"]          # m/s [-128|127.984]
         dRel = cos(azimuth) * dist                              # m from front of car
         yRel = -sin(azimuth) * dist                             # in car frame's y axis, left is positive