jketterl/openwebrx
1
0
Fork 0
mirror of https://github.com/jketterl/openwebrx.git synced 2026-01-05 08:10:12 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity

implement gray decoder

Browse source
This commit is contained in:
Jakob Ketterl 2023-08-28 22:35:34 +02:00
parent 94ee444be7
commit 9d2b626e6f
1 changed files with 12 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

15
owrx/adsb/modes.py
View file

@ -194,9 +194,8 @@ class ModeSParser(PickleModule):
altitude = ((input[5] & 0b11111110) << 3) | ((input[6] & 0b11110000) >> 4)
if q:
message["altitude"] = altitude * 25 - 1000
else:
# TODO: it's gray encoded
message["altitude"] = altitude * 100
elif altitude > 0:
message["altitude"] = self._grayDecode(altitude) * 100
elif type == 19:
# airborne velocity
@ -374,3 +373,13 @@ class ModeSParser(PickleModule):
except StopIteration:
# we don't have both CPR records. better luck next time.
pass
def _grayDecode(self, input: int):
l = input.bit_length()
previous_bit = 0
output = 0
for i in reversed(range(0, l)):
bit = (previous_bit ^ ((input >> i) & 1))
output |= bit << i
previous_bit = bit
return output