From ee41c2b3cccb7fce3e9dbf04a0465a4a96a69491 Mon Sep 17 00:00:00 2001
From: Lars Lindqvist <lars.lindqvist@yandex.ru>
Date: Mon, 15 Aug 2016 12:53:08 +0200
Subject: [PATCH] Adjust bitmask for 13-bit altitude codes with q bit.

Replaced the 14-bit 0x3F80 with 13-bit 0x1F80. (The 14-bit mask
would have produced correct results as long as the input is 13 bit.)
---
 python/altitude.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/python/altitude.py b/python/altitude.py
index 1824194..3519642 100755
--- a/python/altitude.py
+++ b/python/altitude.py
@@ -48,7 +48,7 @@ def decode_alt(alt, bit13):
 			#in this representation, the altitude bits are as follows:
 			# 12 11 10 9 8 7 (6) 5 (4) 3 2 1 0
 			# so bits 6 and 4 are the M and Q bits, respectively.
-			tmp1 = (alt & 0x3F80) >> 2
+			tmp1 = (alt & 0x1F80) >> 2
 			tmp2 = (alt & 0x0020) >> 1
 		else:
 			tmp1 = (alt & 0x1FE0) >> 1