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Decoder recognizes supersonic velocity subtype

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If the aircraft velocity message indicates a supersonic subtype
(2 or 4), multiply the derived velocity by four. This is in accordance
with Table A-2-9[a, b] in the "Technical Provisions for Mode-S Services
and Extended Squitter"
This commit is contained in:
Alexander Hirsch
2019-06-05 16:11:50 -07:00
parent 6159691c3d
commit 4a6d3334a7
1 changed files with 6 additions and 0 deletions
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pyModeS/decoder/bds/bds09.py
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@@ -59,9 +59,13 @@ def airborne_velocity(msg, rtn_sources=False):
if subtype in (1, 2): if subtype in (1, 2):
v_ew_sign = -1 if mb[13]=='1' else 1 v_ew_sign = -1 if mb[13]=='1' else 1
v_ew = common.bin2int(mb[14:24]) - 1 # east-west velocity v_ew = common.bin2int(mb[14:24]) - 1 # east-west velocity
if subtype == 2: # Supersonic
v_ew *= 4
v_ns_sign = -1 if mb[24]=='1' else 1 v_ns_sign = -1 if mb[24]=='1' else 1
v_ns = common.bin2int(mb[25:35]) - 1 # north-south velocity v_ns = common.bin2int(mb[25:35]) - 1 # north-south velocity
if subtype == 2: # Supersonic
v_ns *= 4
v_we = v_ew_sign * v_ew v_we = v_ew_sign * v_ew
v_sn = v_ns_sign * v_ns v_sn = v_ns_sign * v_ns
@@ -88,6 +92,8 @@ def airborne_velocity(msg, rtn_sources=False):
spd = common.bin2int(mb[25:35]) spd = common.bin2int(mb[25:35])
spd = None if spd==0 else spd-1 spd = None if spd==0 else spd-1
if subtype == 4: # Supersonic
spd *= 4
if mb[24]=='0': if mb[24]=='0':
tag = 'IAS' tag = 'IAS'