Flyer350
0eb2d1f6a2
Fix the Mode A decoder. The ZERO is already part of the binary data inside the message and does not need to be added. See ED-102A, 2.2.3.2.7.8.1.2 b. Starting with ―ME‖ bit 12, the code sequence shall be C1, A1, C2, A2, C4, A4, ZERO, B1, D1, B2, D2, B4, D4.
84 lines
2.2 KiB
Python
84 lines
2.2 KiB
Python
# ------------------------------------------
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# BDS 6,1
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# ADS-B TC=28
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# Aircraft Airborne status
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# ------------------------------------------
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from pyModeS import common
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def is_emergency(msg: str) -> bool:
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"""Check if the aircraft is reporting an emergency.
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Non-emergencies are either a subtype of zero (no information) or
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subtype of one and a value of zero (no emergency).
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Subtype = 2 indicates an ACAS RA broadcast, look in BDS 3,0
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:param msg: 28 bytes hexadecimal message string
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:return: if the aircraft has declared an emergency
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"""
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if common.typecode(msg) != 28:
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raise RuntimeError("%s: Not an airborne status message, expecting TC=28" % msg)
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mb = common.hex2bin(msg)[32:]
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subtype = common.bin2int(mb[5:8])
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if subtype == 2:
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raise RuntimeError("%s: Emergency message is ACAS-RA, not implemented")
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emergency_state = common.bin2int(mb[8:11])
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if subtype == 1 and emergency_state == 1:
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return True
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else:
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return False
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def emergency_state(msg: str) -> int:
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"""Decode aircraft emergency state.
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Value Meaning
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----- -----------------------
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0 No emergency
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1 General emergency
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2 Lifeguard/Medical
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3 Minimum fuel
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4 No communications
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5 Unlawful communications
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6-7 Reserved
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:param msg: 28 bytes hexadecimal message string
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:return: emergency state
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"""
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mb = common.hex2bin(msg)[32:]
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subtype = common.bin2int(mb[5:8])
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if subtype == 2:
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raise RuntimeError("%s: Emergency message is ACAS-RA, not implemented")
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emergency_state = common.bin2int(mb[8:11])
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return emergency_state
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def emergency_squawk(msg: str) -> str:
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"""Decode squawk code.
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Emergency value 1: squawk 7700.
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Emergency value 4: squawk 7600.
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Emergency value 5: squawk 7500.
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:param msg: 28 bytes hexadecimal message string
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:return: aircraft squawk code
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"""
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if common.typecode(msg) != 28:
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raise RuntimeError("%s: Not an airborne status message, expecting TC=28" % msg)
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msgbin = common.hex2bin(msg)
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# construct the 13 bits Mode A ID code
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idcode = msgbin[43:56]
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squawk = common.squawk(idcode)
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return squawk
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