From 967a3e9558ad171a7f9ed83b7886cd6796871892 Mon Sep 17 00:00:00 2001
From: Oliver Jowett <oliver@mutability.co.uk>
Date: Wed, 11 Feb 2015 12:10:40 +0000
Subject: [PATCH] If maxRange is >= 360NM, don't do receiver-centered local CPR
 at all.

---
 track.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/track.c b/track.c
index ae7f66f..7751885 100644
--- a/track.c
+++ b/track.c
@@ -198,8 +198,12 @@ static int doLocalCPR(struct aircraft *a, int fflag, int surface, uint64_t now)
         // ambiguity. (e.g. if we receive a position report
         // at 200NM distance, this may resolve to a position
         // at (200-360) = 160NM in the wrong direction)
-        if (Modes.maxRange > 1852*180)
+
+        if (Modes.maxRange > 1852*180) {
             range_limit = (1852*360) - Modes.maxRange;
+            if (range_limit <= 0)
+                return (-1); // Can't do receiver-centered checks at all
+        }
     } else {
         // No local reference, give up
         return (-1);