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[43:49] + "0" + msgbin[49:55]
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squawk = common.squawk(idcode)
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return squawk
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