def airborne_position(msg0, msg1, t0, t1):
"""Decode airborn position from a pair of even and odd position message
Args:
msg0 (string): even message (28 bytes hexadecimal string)
msg1 (string): odd message (28 bytes hexadecimal string)
t0 (int): timestamps for the even message
t1 (int): timestamps for the odd message
Returns:
(float, float): (latitude, longitude) of the aircraft
"""
msgbin0 = util.hex2bin(msg0)
msgbin1 = util.hex2bin(msg1)
# 131072 is 2^17, since CPR lat and lon are 17 bits each.
cprlat_even = util.bin2int(msgbin0[54:71]) / 131072.0
cprlon_even = util.bin2int(msgbin0[71:88]) / 131072.0
cprlat_odd = util.bin2int(msgbin1[54:71]) / 131072.0
cprlon_odd = util.bin2int(msgbin1[71:88]) / 131072.0
air_d_lat_even = 360.0 / 60
air_d_lat_odd = 360.0 / 59
# compute latitude index 'j'
j = util.floor(59 * cprlat_even - 60 * cprlat_odd + 0.5)
lat_even = float(air_d_lat_even * (j % 60 + cprlat_even))
lat_odd = float(air_d_lat_odd * (j % 59 + cprlat_odd))
if lat_even >= 270:
lat_even = lat_even - 360
if lat_odd >= 270:
lat_odd = lat_odd - 360
# check if both are in the same latidude zone, exit if not
if _cprNL(lat_even) != _cprNL(lat_odd):
return None
# compute ni, longitude index m, and longitude
if (t0 > t1):
lat = lat_even
nl = _cprNL(lat)
ni = max(_cprNL(lat) - 0, 1)
m = util.floor(cprlon_even * (nl - 1) - cprlon_odd * nl + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_even)
else:
lat = lat_odd
nl = _cprNL(lat)
ni = max(_cprNL(lat) - 1, 1)
m = util.floor(cprlon_even * (nl - 1) - cprlon_odd * nl + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_odd)
if lon > 180:
lon = lon - 360
return round(lat, 5), round(lon, 5)
def callsign(msg):
"""Aircraft callsign
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
string: callsign
"""
if typecode(msg) < 1 or typecode(msg) > 4:
raise RuntimeError("%s: Not a identification message" % msg)
chars = '#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_###############0123456789######'
msgbin = util.hex2bin(msg)
csbin = msgbin[40:96]
cs = ''
cs += chars[util.bin2int(csbin[0:6])]
cs += chars[util.bin2int(csbin[6:12])]
cs += chars[util.bin2int(csbin[12:18])]
cs += chars[util.bin2int(csbin[18:24])]
cs += chars[util.bin2int(csbin[24:30])]
cs += chars[util.bin2int(csbin[30:36])]
cs += chars[util.bin2int(csbin[36:42])]
cs += chars[util.bin2int(csbin[42:48])]
# clean string, remove spaces and marks, if any.
# cs = cs.replace('_', '')
cs = cs.replace('#', '')
return cs
def callsign(msg):
"""Aircraft callsign
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
string: callsign
"""
if typecode(msg) < 1 or typecode(msg) > 4:
raise RuntimeError("%s: Not a identification message" % msg)
chars = '#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_###############0123456789######'
msgbin = util.hex2bin(msg)
csbin = msgbin[40:96]
cs = ''
cs += chars[util.bin2int(csbin[0:6])]
cs += chars[util.bin2int(csbin[6:12])]
cs += chars[util.bin2int(csbin[12:18])]
cs += chars[util.bin2int(csbin[18:24])]
cs += chars[util.bin2int(csbin[24:30])]
cs += chars[util.bin2int(csbin[30:36])]
cs += chars[util.bin2int(csbin[36:42])]
cs += chars[util.bin2int(csbin[42:48])]
# clean string, remove spaces and marks, if any.
# cs = cs.replace('_', '')
cs = cs.replace('#', '')
return cs
def _generateRandomID(
self,
c1 = constants.CRYPTO_CHALLENGE_C1,
c2 = constants.CRYPTO_CHALLENGE_C2):
"""Generates the NodeID by solving two cryptographic puzzles."""
# Solve the static cryptographic puzzle.
rsaKey = None
p = 0x1 # non-zero value
pub = None
randomStream = Crypto.Random.new().read
while not util.hasNZeroBitPrefix(p, c1):
rsaKey = Crypto.PublicKey.RSA.generate(constants.RSA_BITS, randomStream)
pub = str(rsaKey.n) + str(rsaKey.e)
p = util.hsh2int(Crypto.Hash.SHA.new(Crypto.Hash.SHA.new(pub).digest()))
# created correct NodeID
self.rsaKey = rsaKey
nodeID = Crypto.Hash.SHA.new(pub)
# Solve the dynamic cryptographic puzzle.
p, x = 0x1, None
while not util.hasNZeroBitPrefix(p, c2):
x = util.bin2int(util.generateRandomString(constants.ID_LENGTH))
# This is madness!
p = util.hsh2int(
Crypto.Hash.SHA.new(
util.int2bin(
(util.hsh2int(nodeID) ^ x))))
# Found a correct value of X and nodeID
self.x = x
return nodeID.digest()
def typecode(msg):
"""Type code of ADS-B message
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: type code number
"""
msgbin = util.hex2bin(msg)
return util.bin2int(msgbin[32:37])
def typecode(msg):
"""Type code of ADS-B message
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: type code number
"""
msgbin = util.hex2bin(msg)
return util.bin2int(msgbin[32:37])
def _verifyID(self, nodeID, x):
'''Verifies if a user's ID has been generated using the '''
p1 = util.hsh2int(Crypto.Hash.SHA.new(nodeID))
p2 = util.hsh2int(Crypto.Hash.SHA.new(
util.int2bin((util.bin2int(nodeID) ^ x))))
# check preceeding c_i bits in P1 and P2 using sharesXPrefices.
return (
util.hasNZeroBitPrefix(p1, constants.CRYPTO_CHALLENGE_C1) and
util.hasNZeroBitPrefix(p2, constants.CRYPTO_CHALLENGE_C2))
def pbaro(msg):
"""Barometric pressure setting
Args:
msg (String): 28 bytes hexadecimal message (BDS40) string
Returns:
float: pressure in millibar
"""
d = util.hex2bin(data(msg))
p = util.bin2int(d[27:39]) * 0.1 + 800 # millibar
return p
def gs(msg):
"""Aircraft ground speed
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
int: ground speed in knots
"""
d = util.hex2bin(data(msg))
spd = util.bin2int(d[24:34]) * 2 # kts
return spd
def alt_fms(msg):
"""Selected altitude, FMS
Args:
msg (String): 28 bytes hexadecimal message (BDS40) string
Returns:
int: altitude in feet
"""
d = util.hex2bin(data(msg))
alt = util.bin2int(d[14:26]) * 16 # ft
return alt
def alt_fms(msg):
"""Selected altitude, FMS
Args:
msg (String): 28 bytes hexadecimal message (BDS40) string
Returns:
int: altitude in feet
"""
d = util.hex2bin(data(msg))
alt = util.bin2int(d[14:26]) * 16 # ft
return alt
def gs(msg):
"""Aircraft ground speed
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
int: ground speed in knots
"""
d = util.hex2bin(data(msg))
spd = util.bin2int(d[24:34]) * 2 # kts
return spd
def mach(msg):
"""Aircraft MACH number
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
float: MACH number
"""
d = util.hex2bin(data(msg))
mach = util.bin2int(d[24:34]) * 2.048 / 512.0
return round(mach, 3)
def ias(msg):
"""Indicated airspeed
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
int: indicated airspeed in knots
"""
d = util.hex2bin(data(msg))
ias = util.bin2int(d[13:23]) # kts
return ias
def mach(msg):
"""Aircraft MACH number
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
float: MACH number
"""
d = util.hex2bin(data(msg))
mach = util.bin2int(d[24:34]) * 2.048 / 512.0
return round(mach, 3)
def pbaro(msg):
"""Barometric pressure setting
Args:
msg (String): 28 bytes hexadecimal message (BDS40) string
Returns:
float: pressure in millibar
"""
d = util.hex2bin(data(msg))
p = util.bin2int(d[27:39]) * 0.1 + 800 # millibar
return p
def ias(msg):
"""Indicated airspeed
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
int: indicated airspeed in knots
"""
d = util.hex2bin(data(msg))
ias = util.bin2int(d[13:23]) # kts
return ias
def tas(msg):
"""Aircraft true airspeed
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
int: true airspeed in knots
"""
d = util.hex2bin(data(msg))
spd = util.bin2int(d[46:56]) * 2 # kts
return spd
def tas(msg):
"""Aircraft true airspeed
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
int: true airspeed in knots
"""
d = util.hex2bin(data(msg))
spd = util.bin2int(d[46:56]) * 2 # kts
return spd
def velocity(msg):
"""Calculate the speed, heading, and vertical rate
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
(int, float, int, string): speed (kt), heading (degree),
rate of climb/descend (ft/min), and speed type
('GS' for ground speed, 'AS' for airspeed)
"""
if typecode(msg) != 19:
raise RuntimeError("%s: Not a airborne velocity message" % msg)
msgbin = util.hex2bin(msg)
subtype = util.bin2int(msgbin[37:40])
if subtype in (1, 2):
v_ew_sign = util.bin2int(msgbin[45])
v_ew = util.bin2int(msgbin[46:56]) - 1 # east-west velocity
v_ns_sign = util.bin2int(msgbin[56])
v_ns = util.bin2int(msgbin[57:67]) - 1 # north-south velocity
v_we = -1*v_ew if v_ew_sign else v_ew
v_sn = -1*v_ns if v_ns_sign else v_ns
spd = math.sqrt(v_sn*v_sn + v_we*v_we) # unit in kts
hdg = math.atan2(v_we, v_sn)
hdg = math.degrees(hdg) # convert to degrees
hdg = hdg if hdg >= 0 else hdg + 360 # no negative val
tag = 'GS'
else:
hdg = util.bin2int(msgbin[46:56]) / 1024.0 * 360.0
spd = util.bin2int(msgbin[57:67])
tag = 'AS'
vr_sign = util.bin2int(msgbin[68])
vr = util.bin2int(msgbin[68:77]) # vertical rate
rocd = -1*vr if vr_sign else vr # rate of climb/descend
return int(spd), round(hdg, 1), int(rocd), tag
def surface_velocity(msg):
"""Decode surface velocity from from a surface position message
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
(int, float, int, string): speed (kt), heading (degree),
rate of climb/descend (ft/min), and speed type
('GS' for ground speed, 'AS' for airspeed)
"""
if typecode(msg) < 5 or typecode(msg) > 8:
raise RuntimeError("%s: Not a surface message, expecting 5<TC<8" % msg)
msgbin = util.hex2bin(msg)
# heading
hdg_status = int(msgbin[44])
if hdg_status == 1:
hdg = util.bin2int(msgbin[45:52]) * 360.0 / 128.0
hdg = round(hdg, 1)
else:
hdg = None
# ground movment / speed
mov = util.bin2int(msgbin[37:44])
if mov == 0 or mov > 124:
spd = None
elif mov == 1:
spd = 0
elif mov == 124:
spd = 175
else:
movs = [2, 9, 13, 39, 94, 109, 124]
kts = [0.125, 1, 2, 15, 70, 100, 175]
i = next(m[0] for m in enumerate(movs) if m[1] > mov)
step = (kts[i] - kts[i - 1]) * 1.0 / (movs[i] - movs[i - 1])
spd = kts[i - 1] + (mov - movs[i - 1]) * step
spd = round(spd, 2)
return spd, hdg, 0, 'GS'
def velocity(msg):
"""Calculate the speed, heading, and vertical rate
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
(int, float, int, string): speed (kt), heading (degree),
rate of climb/descend (ft/min), and speed type
('GS' for ground speed, 'AS' for airspeed)
"""
if typecode(msg) != 19:
raise RuntimeError("%s: Not a airborne velocity message" % msg)
msgbin = util.hex2bin(msg)
subtype = util.bin2int(msgbin[37:40])
if subtype in (1, 2):
v_ew_sign = util.bin2int(msgbin[45])
v_ew = util.bin2int(msgbin[46:56]) - 1 # east-west velocity
v_ns_sign = util.bin2int(msgbin[56])
v_ns = util.bin2int(msgbin[57:67]) - 1 # north-south velocity
v_we = -1 * v_ew if v_ew_sign else v_ew
v_sn = -1 * v_ns if v_ns_sign else v_ns
spd = math.sqrt(v_sn * v_sn + v_we * v_we) # unit in kts
hdg = math.atan2(v_we, v_sn)
hdg = math.degrees(hdg) # convert to degrees
hdg = hdg if hdg >= 0 else hdg + 360 # no negative val
tag = 'GS'
else:
hdg = util.bin2int(msgbin[46:56]) / 1024.0 * 360.0
spd = util.bin2int(msgbin[57:67])
tag = 'AS'
vr_sign = util.bin2int(msgbin[68])
vr = util.bin2int(msgbin[68:77]) # vertical rate
rocd = -1 * vr if vr_sign else vr # rate of climb/descend
return int(spd), round(hdg, 1), int(rocd), tag
def track(msg):
"""True track angle
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
float: angle in degrees to true north (from 0 to 360)
"""
d = util.hex2bin(data(msg))
sign = int(d[12]) # 1 -> west
value = util.bin2int(d[13:23]) * 90 / 512.0 # degree
angle = 360 - value if sign else value
return round(angle, 1)
def baro_vr(msg):
"""Vertical rate from barometric measurement
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
int: vertical rate in feet/minutes
"""
d = util.hex2bin(data(msg))
sign = d[35] # 1 -> minus
value = util.bin2int(d[36:45]) * 32 # feet/min
roc = -1 * value if sign else value
return roc
def cprlon(msg):
"""CPR encoded longitude
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: encoded longitude
"""
if typecode(msg) < 5 or typecode(msg) > 18:
raise RuntimeError("%s: Not a position message" % msg)
msgbin = util.hex2bin(msg)
return util.bin2int(msgbin[71:88])
def category(msg):
"""Aircraft category number
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: category number
"""
if typecode(msg) < 1 or typecode(msg) > 4:
raise RuntimeError("%s: Not a identification message" % msg)
msgbin = util.hex2bin(msg)
return util.bin2int(msgbin[5:8])
def heading(msg):
"""Megnetic heading of aircraft
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
float: heading in degrees to megnetic north (from 0 to 360)
"""
d = util.hex2bin(data(msg))
sign = int(d[1]) # 1 -> west
value = util.bin2int(d[2:12]) * 90 / 512.0 # degree
hdg = 360 - value if sign else value
return round(hdg, 1)
def rtrack(msg):
"""Track angle rate
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
float: angle rate in degrees/second
"""
d = util.hex2bin(data(msg))
sign = int(d[35]) # 1 -> minus
value = util.bin2int(d[36:45]) * 8 / 256.0 # degree / sec
angle = -1 * value if sign else value
return round(angle, 3)
def ins_vr(msg):
"""Vertical rate messured by onbard equiments (IRS, AHRS)
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
int: vertical rate in feet/minutes
"""
d = util.hex2bin(data(msg))
sign = d[46] # 1 -> minus
value = util.bin2int(d[47:56]) * 32 # feet/min
roc = -1 * value if sign else value
return roc
def rtrack(msg):
"""Track angle rate
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
float: angle rate in degrees/second
"""
d = util.hex2bin(data(msg))
sign = int(d[35]) # 1 -> minus
value = util.bin2int(d[36:45]) * 8 / 256.0 # degree / sec
angle = -1 * value if sign else value
return round(angle, 3)
def track(msg):
"""True track angle
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
float: angle in degrees to true north (from 0 to 360)
"""
d = util.hex2bin(data(msg))
sign = int(d[12]) # 1 -> west
value = util.bin2int(d[13:23]) * 90 / 512.0 # degree
angle = 360 - value if sign else value
return round(angle, 1)
def category(msg):
"""Aircraft category number
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: category number
"""
if typecode(msg) < 1 or typecode(msg) > 4:
raise RuntimeError("%s: Not a identification message" % msg)
msgbin = util.hex2bin(msg)
return util.bin2int(msgbin[5:8])
def baro_vr(msg):
"""Vertical rate from barometric measurement
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
int: vertical rate in feet/minutes
"""
d = util.hex2bin(data(msg))
sign = d[35] # 1 -> minus
value = util.bin2int(d[36:45]) * 32 # feet/min
roc = -1*value if sign else value
return roc
def heading(msg):
"""Megnetic heading of aircraft
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
float: heading in degrees to megnetic north (from 0 to 360)
"""
d = util.hex2bin(data(msg))
sign = int(d[1]) # 1 -> west
value = util.bin2int(d[2:12]) * 90 / 512.0 # degree
hdg = 360 - value if sign else value
return round(hdg, 1)
def ins_vr(msg):
"""Vertical rate messured by onbard equiments (IRS, AHRS)
Args:
msg (String): 28 bytes hexadecimal message (BDS60) string
Returns:
int: vertical rate in feet/minutes
"""
d = util.hex2bin(data(msg))
sign = d[46] # 1 -> minus
value = util.bin2int(d[47:56]) * 32 # feet/min
roc = -1*value if sign else value
return roc
def isBDS20(msg):
"""Check if a message is likely to be BDS code 2,0
Args:
msg (String): 28 bytes hexadecimal message string
Returns:
bool: True or False
"""
# status bit 1, 14, and 27
d = util.hex2bin(data(msg))
result = True
if util.bin2int(d[0:4]) != 2 or util.bin2int(d[4:8]) != 0:
result &= False
cs = callsign(msg)
if '#' in cs:
result &= False
return result
def cprlon(msg):
"""CPR encoded longitude
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: encoded longitude
"""
if typecode(msg) < 5 or typecode(msg) > 18:
raise RuntimeError("%s: Not a position message" % msg)
msgbin = util.hex2bin(msg)
return util.bin2int(msgbin[71:88])
def isBDS20(msg):
"""Check if a message is likely to be BDS code 2,0
Args:
msg (String): 28 bytes hexadecimal message string
Returns:
bool: True or False
"""
# status bit 1, 14, and 27
d = util.hex2bin(data(msg))
result = True
if util.bin2int(d[0:4]) != 2 or util.bin2int(d[4:8]) != 0:
result &= False
cs = callsign(msg)
if '#' in cs:
result &= False
return result
def roll(msg):
"""Aircraft roll angle
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
float: angle in degrees,
negative->left wing down, positive->right wing down
"""
d = util.hex2bin(data(msg))
sign = int(d[1]) # 1 -> left wing down
value = util.bin2int(d[2:11]) * 45 / 256.0 # degree
angle = -1 * value if sign else value
return round(angle, 1)
def roll(msg):
"""Aircraft roll angle
Args:
msg (String): 28 bytes hexadecimal message (BDS50) string
Returns:
float: angle in degrees,
negative->left wing down, positive->right wing down
"""
d = util.hex2bin(data(msg))
sign = int(d[1]) # 1 -> left wing down
value = util.bin2int(d[2:11]) * 45 / 256.0 # degree
angle = -1 * value if sign else value
return round(angle, 1)
def checkbits(data, sb, msb, lsb):
"""Check if the status bit and field bits are consistency. This Function
is used for checking BDS code versions.
"""
# status bit, most significant bit, least significant bit
status = int(data[sb - 1])
value = util.bin2int(data[msb - 1:lsb])
if not status:
if value != 0:
return False
return True
def checkbits(data, sb, msb, lsb):
"""Check if the status bit and field bits are consistency. This Function
is used for checking BDS code versions.
"""
# status bit, most significant bit, least significant bit
status = int(data[sb-1])
value = util.bin2int(data[msb-1:lsb])
if not status:
if value != 0:
return False
return True
def surface_position_with_ref(msg, lat_ref, lon_ref):
"""Decode surface position with only one message,
knowing reference nearby location, such as previously calculated location,
ground station, or airport location, etc. The reference position shall
be with in 45NM of the true position.
Args:
msg (string): even message (28 bytes hexadecimal string)
lat_ref: previous known latitude
lon_ref: previous known longitude
Returns:
(float, float): (latitude, longitude) of the aircraft
"""
i = oe_flag(msg)
d_lat = 90.0 / 59 if i else 90.0 / 60
msgbin = util.hex2bin(msg)
cprlat = util.bin2int(msgbin[54:71]) / 131072.0
cprlon = util.bin2int(msgbin[71:88]) / 131072.0
j = util.floor(lat_ref / d_lat) \
+ util.floor(0.5 + ((lat_ref % d_lat) / d_lat) - cprlat)
lat = d_lat * (j + cprlat)
ni = _cprNL(lat) - i
if ni > 0:
d_lon = 90.0 / ni
else:
d_lon = 90.0
m = util.floor(lon_ref / d_lon) \
+ util.floor(0.5 + ((lon_ref % d_lon) / d_lon) - cprlon)
lon = d_lon * (m + cprlon)
return round(lat, 5), round(lon, 5)
def isBDS40(msg):
"""Check if a message is likely to be BDS code 4,0
Args:
msg (String): 28 bytes hexadecimal message string
Returns:
bool: True or False
"""
# status bit 1, 14, and 27
d = util.hex2bin(data(msg))
result = True
result = result & checkbits(d, 1, 2, 13) \
& checkbits(d, 14, 15, 26) & checkbits(d, 27, 28, 39)
# bits 40-47 and 52-53 shall all be zero
if util.bin2int(d[39:47]) != 0:
result &= False
if util.bin2int(d[51:53]) != 0:
result &= False
return result
def isBDS40(msg):
"""Check if a message is likely to be BDS code 4,0
Args:
msg (String): 28 bytes hexadecimal message string
Returns:
bool: True or False
"""
# status bit 1, 14, and 27
d = util.hex2bin(data(msg))
result = True
result = result & checkbits(d, 1, 2, 13) \
& checkbits(d, 14, 15, 26) & checkbits(d, 27, 28, 39)
# bits 40-47 and 52-53 shall all be zero
if util.bin2int(d[39:47]) != 0:
result &= False
if util.bin2int(d[51:53]) != 0:
result &= False
return result
def icao(msg):
"""Calculate the ICAO address from an Mode-S message
with DF4, DF5, DF20, DF21
Args:
msg (String): 28 bytes hexadecimal message string
Returns:
String: ICAO address in 6 bytes hexadecimal string
"""
if df(msg) not in (4, 5, 20, 21):
# raise RuntimeError("Message DF must be in (4, 5, 20, 21)")
return None
c0 = util.bin2int(crc(msg, encode=True))
c1 = util.hex2int(msg[-6:])
icao = '%06X' % (c0 ^ c1)
return icao
def icao(msg):
"""Calculate the ICAO address from an Mode-S message
with DF4, DF5, DF20, DF21
Args:
msg (String): 28 bytes hexadecimal message string
Returns:
String: ICAO address in 6 bytes hexadecimal string
"""
if df(msg) not in (4, 5, 20, 21):
# raise RuntimeError("Message DF must be in (4, 5, 20, 21)")
return None
c0 = util.bin2int(crc(msg, encode=True))
c1 = util.hex2int(msg[-6:])
icao = '%06X' % (c0 ^ c1)
return icao
def altitude(msg):
"""Decode aircraft altitude
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: altitude in feet
"""
if typecode(msg) < 9 or typecode(msg) > 18:
raise RuntimeError("%s: Not a position message" % msg)
msgbin = util.hex2bin(msg)
q = msgbin[47]
if q:
n = util.bin2int(msgbin[40:47]+msgbin[48:52])
alt = n * 25 - 1000
return alt
else:
return None
def altitude(msg):
"""Decode aircraft altitude
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: altitude in feet
"""
if typecode(msg) < 9 or typecode(msg) > 18:
raise RuntimeError("%s: Not a position message" % msg)
msgbin = util.hex2bin(msg)
q = msgbin[47]
if q:
n = util.bin2int(msgbin[40:47] + msgbin[48:52])
alt = n * 25 - 1000
return alt
else:
return None
def nic(msg):
"""Calculate NIC, navigation integrity category
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: NIC number (from 0 to 11), -1 if not applicable
"""
if typecode(msg) < 9 or typecode(msg) > 18:
raise RuntimeError(
"%s: Not a airborne position message, expecting 8<TC<19" % msg)
msgbin = util.hex2bin(msg)
tc = typecode(msg)
nic_sup_b = util.bin2int(msgbin[39])
if tc in [0, 18, 22]:
nic = 0
elif tc == 17:
nic = 1
elif tc == 16:
if nic_sup_b:
nic = 3
else:
nic = 2
elif tc == 15:
nic = 4
elif tc == 14:
nic = 5
elif tc == 13:
nic = 6
elif tc == 12:
nic = 7
elif tc == 11:
if nic_sup_b:
nic = 9
else:
nic = 8
elif tc in [10, 21]:
nic = 10
elif tc in [9, 20]:
nic = 11
else:
nic = -1
return nic
def nic(msg):
"""Calculate NIC, navigation integrity category
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: NIC number (from 0 to 11), -1 if not applicable
"""
if typecode(msg) < 9 or typecode(msg) > 18:
raise RuntimeError("%s: Not a airborne position message" % msg)
msgbin = util.hex2bin(msg)
tc = typecode(msg)
nic_sup_b = util.bin2int(msgbin[39])
if tc in [0, 18, 22]:
nic = 0
elif tc == 17:
nic = 1
elif tc == 16:
if nic_sup_b:
nic = 3
else:
nic = 2
elif tc == 15:
nic = 4
elif tc == 14:
nic = 5
elif tc == 13:
nic = 6
elif tc == 12:
nic = 7
elif tc == 11:
if nic_sup_b:
nic = 9
else:
nic = 8
elif tc in [10, 21]:
nic = 10
elif tc in [9, 20]:
nic = 11
else:
nic = -1
return nic
def callsign(msg):
"""Aircraft callsign
Args:
msg (String): 28 bytes hexadecimal message (BDS40) string
Returns:
string: callsign, max. 8 chars
"""
chars = '#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_###############0123456789######'
d = util.hex2bin(data(msg))
cs = ''
cs += chars[util.bin2int(d[8:14])]
cs += chars[util.bin2int(d[14:20])]
cs += chars[util.bin2int(d[20:26])]
cs += chars[util.bin2int(d[26:32])]
cs += chars[util.bin2int(d[32:38])]
cs += chars[util.bin2int(d[38:44])]
cs += chars[util.bin2int(d[44:50])]
cs += chars[util.bin2int(d[50:56])]
return cs
def altitude_diff(msg):
"""Decode the differece between GNSS and barometric altitude
Args:
msg (string): 28 bytes hexadecimal message string, TC=19
Returns:
int: Altitude difference in ft. Negative value indicates GNSS altitude
below barometric altitude.
"""
if typecode(msg) != 19:
raise RuntimeError("incorrect message types, expecting TC=19")
msgbin = util.hex2bin(msg)
sign = -1 if int(msgbin[80]) else 1
value = util.bin2int(msgbin[81:88])
if value == 0 or value == 127:
return None
else:
return sign * (value - 1) * 25 # in ft.
def callsign(msg):
"""Aircraft callsign
Args:
msg (String): 28 bytes hexadecimal message (BDS40) string
Returns:
string: callsign, max. 8 chars
"""
chars = '#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_###############0123456789######'
d = util.hex2bin(data(msg))
cs = ''
cs += chars[util.bin2int(d[8:14])]
cs += chars[util.bin2int(d[14:20])]
cs += chars[util.bin2int(d[20:26])]
cs += chars[util.bin2int(d[26:32])]
cs += chars[util.bin2int(d[32:38])]
cs += chars[util.bin2int(d[38:44])]
cs += chars[util.bin2int(d[44:50])]
cs += chars[util.bin2int(d[50:56])]
return cs
def position(msg0, msg1, t0, t1):
"""Decode position from the combination of even and odd position message
131072 is 2^17, since CPR lat and lon are 17 bits each.
Args:
msg0 (string): even message (28 bytes hexadecimal string)
msg1 (string): odd message (28 bytes hexadecimal string)
t0 (int): timestamps for the even message
t1 (int): timestamps for the odd message
Returns:
(float, float): (latitude, longitude) of the aircraft
"""
if typecode(msg0) < 5 or typecode(msg0) > 18:
raise RuntimeError("%s: Not a position message" % msg0)
if typecode(msg1) < 5 or typecode(msg1) > 18:
raise RuntimeError("%s: Not a position message" % msg1)
msgbin0 = util.hex2bin(msg0)
msgbin1 = util.hex2bin(msg1)
cprlat_even = util.bin2int(msgbin0[54:71]) / 131072.0
cprlon_even = util.bin2int(msgbin0[71:88]) / 131072.0
cprlat_odd = util.bin2int(msgbin1[54:71]) / 131072.0
cprlon_odd = util.bin2int(msgbin1[71:88]) / 131072.0
air_d_lat_even = 360.0 / 60
air_d_lat_odd = 360.0 / 59
# compute latitude index 'j'
j = int(math.floor(59 * cprlat_even - 60 * cprlat_odd + 0.5))
lat_even = float(air_d_lat_even * (j % 60 + cprlat_even))
lat_odd = float(air_d_lat_odd * (j % 59 + cprlat_odd))
if lat_even >= 270:
lat_even = lat_even - 360
if lat_odd >= 270:
lat_odd = lat_odd - 360
# check if both are in the same latidude zone, exit if not
if _cprNL(lat_even) != _cprNL(lat_odd):
return None
# compute ni, longitude index m, and longitude
if (t0 > t1):
ni = _cprN(lat_even, 0)
m = math.floor(cprlon_even * (_cprNL(lat_even)-1) -
cprlon_odd * _cprNL(lat_even) + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_even)
lat = lat_even
else:
ni = _cprN(lat_odd, 1)
m = math.floor(cprlon_even * (_cprNL(lat_odd)-1) -
cprlon_odd * _cprNL(lat_odd) + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_odd)
lat = lat_odd
if lon > 180:
lon = lon - 360
return round(lat, 5), round(lon, 5)
def surface_position(msg0, msg1, t0, t1, lat_ref, lon_ref):
"""Decode surface position from a pair of even and odd position message,
the lat/lon of receiver must be provided to yield the correct solution.
Args:
msg0 (string): even message (28 bytes hexadecimal string)
msg1 (string): odd message (28 bytes hexadecimal string)
t0 (int): timestamps for the even message
t1 (int): timestamps for the odd message
lat_ref (float): latitude of the receiver
lon_ref (float): longitude of the receiver
Returns:
(float, float): (latitude, longitude) of the aircraft
"""
msgbin0 = util.hex2bin(msg0)
msgbin1 = util.hex2bin(msg1)
# 131072 is 2^17, since CPR lat and lon are 17 bits each.
cprlat_even = util.bin2int(msgbin0[54:71]) / 131072.0
cprlon_even = util.bin2int(msgbin0[71:88]) / 131072.0
cprlat_odd = util.bin2int(msgbin1[54:71]) / 131072.0
cprlon_odd = util.bin2int(msgbin1[71:88]) / 131072.0
air_d_lat_even = 90.0 / 60
air_d_lat_odd = 90.0 / 59
# compute latitude index 'j'
j = util.floor(59 * cprlat_even - 60 * cprlat_odd + 0.5)
# solution for north hemisphere
lat_even_n = float(air_d_lat_even * (j % 60 + cprlat_even))
lat_odd_n = float(air_d_lat_odd * (j % 59 + cprlat_odd))
# solution for north hemisphere
lat_even_s = lat_even_n - 90.0
lat_odd_s = lat_odd_n - 90.0
# chose which solution corrispondes to receiver location
lat_even = lat_even_n if lat_ref > 0 else lat_even_s
lat_odd = lat_odd_n if lat_ref > 0 else lat_odd_s
# check if both are in the same latidude zone, rare but possible
if _cprNL(lat_even) != _cprNL(lat_odd):
return None
# compute ni, longitude index m, and longitude
if (t0 > t1):
lat = lat_even
nl = _cprNL(lat_even)
ni = max(_cprNL(lat_even) - 0, 1)
m = util.floor(cprlon_even * (nl - 1) - cprlon_odd * nl + 0.5)
lon = (90.0 / ni) * (m % ni + cprlon_even)
else:
lat = lat_odd
nl = _cprNL(lat_odd)
ni = max(_cprNL(lat_odd) - 1, 1)
m = util.floor(cprlon_even * (nl - 1) - cprlon_odd * nl + 0.5)
lon = (90.0 / ni) * (m % ni + cprlon_odd)
# four possible longitude solutions
lons = [lon, lon + 90.0, lon + 180.0, lon + 270.0]
# the closest solution to receiver is the correct one
dls = [abs(lon_ref - l) for l in lons]
imin = min(range(4), key=dls.__getitem__)
lon = lons[imin]
return round(lat, 5), round(lon, 5)
def position(msg0, msg1, t0, t1):
"""Decode position from the combination of even and odd position message
131072 is 2^17, since CPR lat and lon are 17 bits each.
Args:
msg0 (string): even message (28 bytes hexadecimal string)
msg1 (string): odd message (28 bytes hexadecimal string)
t0 (int): timestamps for the even message
t1 (int): timestamps for the odd message
Returns:
(float, float): (latitude, longitude) of the aircraft
"""
if typecode(msg0) < 5 or typecode(msg0) > 18:
raise RuntimeError("%s: Not a position message" % msg0)
if typecode(msg1) < 5 or typecode(msg1) > 18:
raise RuntimeError("%s: Not a position message" % msg1)
msgbin0 = util.hex2bin(msg0)
msgbin1 = util.hex2bin(msg1)
cprlat_even = util.bin2int(msgbin0[54:71]) / 131072.0
cprlon_even = util.bin2int(msgbin0[71:88]) / 131072.0
cprlat_odd = util.bin2int(msgbin1[54:71]) / 131072.0
cprlon_odd = util.bin2int(msgbin1[71:88]) / 131072.0
air_d_lat_even = 360.0 / 60
air_d_lat_odd = 360.0 / 59
# compute latitude index 'j'
j = int(math.floor(59 * cprlat_even - 60 * cprlat_odd + 0.5))
lat_even = float(air_d_lat_even * (j % 60 + cprlat_even))
lat_odd = float(air_d_lat_odd * (j % 59 + cprlat_odd))
if lat_even >= 270:
lat_even = lat_even - 360
if lat_odd >= 270:
lat_odd = lat_odd - 360
# check if both are in the same latidude zone, exit if not
if _cprNL(lat_even) != _cprNL(lat_odd):
return None
# compute ni, longitude index m, and longitude
if (t0 > t1):
ni = _cprN(lat_even, 0)
m = math.floor(cprlon_even * (_cprNL(lat_even) - 1) -
cprlon_odd * _cprNL(lat_even) + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_even)
lat = lat_even
else:
ni = _cprN(lat_odd, 1)
m = math.floor(cprlon_even * (_cprNL(lat_odd) - 1) -
cprlon_odd * _cprNL(lat_odd) + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_odd)
lat = lat_odd
if lon > 180:
lon = lon - 360
return round(lat, 5), round(lon, 5)
