add bds05

This commit is contained in:
Xavier Olive 2019-10-29 11:41:00 +01:00
parent eb675d5ca3
commit d48caed7e6
5 changed files with 224 additions and 9 deletions

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# Copyright (C) 2018 Junzi Sun (TU Delft)
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# ------------------------------------------
# BDS 0,5
# ADS-B TC=9-18
# Airborn position
# ------------------------------------------
# cython: language_level=3
cimport cython
from .. cimport common
from libc.math cimport NAN as nan, round as c_round
@cython.cdivision(True)
def airborne_position(bytes msg0 not None, bytes msg1 not None, long t0, long 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
"""
cdef bytearray mb0 = common.hex2bin(msg0)[32:]
cdef bytearray mb1 = common.hex2bin(msg1)[32:]
cdef unsigned char oe0 = common.char_to_int(mb0[21])
cdef unsigned char oe1 = common.char_to_int(mb1[21])
if oe0 == 0 and oe1 == 1:
pass
elif oe0 == 1 and oe1 == 0:
mb0, mb1 = mb1, mb0
t0, t1 = t1, t0
else:
raise RuntimeError("Both even and odd CPR frames are required.")
# 131072 is 2^17, since CPR lat and lon are 17 bits each.
cdef double cprlat_even = common.bin2int(mb0[22:39]) / 131072.0
cdef double cprlon_even = common.bin2int(mb0[39:56]) / 131072.0
cdef double cprlat_odd = common.bin2int(mb1[22:39]) / 131072.0
cdef double cprlon_odd = common.bin2int(mb1[39:56]) / 131072.0
cdef double air_d_lat_even = 360.0 / 60
cdef double air_d_lat_odd = 360.0 / 59
# compute latitude index 'j'
cdef long j = common.floor(59 * cprlat_even - 60 * cprlat_odd + 0.5)
cdef double lat_even = (air_d_lat_even * (j % 60 + cprlat_even))
cdef double lat_odd = (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 common.cprNL(lat_even) != common.cprNL(lat_odd):
return nan
cdef int nl, ni, m
cdef double lat, lon
# compute ni, longitude index m, and longitude
if t0 > t1:
lat = lat_even
nl = common.cprNL(lat)
# ni = max(common.cprNL(lat) - 0, 1)
ni = common.cprNL(lat)
if ni < 1:
ni = 1
m = common.floor(cprlon_even * (nl - 1) - cprlon_odd * nl + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_even)
else:
lat = lat_odd
nl = common.cprNL(lat)
# ni = max(common.cprNL(lat) - 1, 1)
ni = common.cprNL(lat) - 1
if ni < 1:
ni = 1
m = common.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)
@cython.cdivision(True)
def airborne_position_with_ref(bytes msg not None, double lat_ref, double lon_ref):
"""Decode airborne 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 180NM 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
"""
cdef bytearray mb = common.hex2bin(msg)[32:]
cdef double cprlat = common.bin2int(mb[22:39]) / 131072.0
cdef double cprlon = common.bin2int(mb[39:56]) / 131072.0
cdef unsigned char i = common.char_to_int(mb[21])
cdef double d_lat = 360.0 / 59 if i else 360.0 / 60
cdef long j = common.floor(lat_ref / d_lat) + common.floor(
0.5 + ((lat_ref % d_lat) / d_lat) - cprlat
)
cdef double lat = d_lat * (j + cprlat)
cdef double d_lon, lon
cdef int ni = common.cprNL(lat) - i
if ni > 0:
d_lon = 360.0 / ni
else:
d_lon = 360.0
cdef int m = common.floor(lon_ref / d_lon) + common.floor(
0.5 + ((lon_ref % d_lon) / d_lon) - cprlon
)
lon = d_lon * (m + cprlon)
return round(lat, 5), round(lon, 5)
cpdef double altitude(bytes msg):
"""Decode aircraft altitude
Args:
msg (string): 28 bytes hexadecimal message string
Returns:
int: altitude in feet
"""
cdef int tc = common.typecode(msg)
if tc < 9 or tc == 19 or tc > 22:
raise RuntimeError("%s: Not a airborn position message" % msg)
cdef bytearray mb = common.hex2bin(msg)[32:]
cdef unsigned char q
cdef int n
cdef double alt
if tc < 19:
# barometric altitude
q = mb[15]
if q:
n = common.bin2int(mb[8:15] + mb[16:20])
alt = n * 25 - 1000
else:
alt = nan
else:
# GNSS altitude, meters -> feet
alt = common.bin2int(mb[8:20]) * 3.28084
return alt

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# cython: language_level=3
cdef int char_to_int(unsigned char binstr)
cdef unsigned char int_to_char(unsigned char i)
cpdef bytearray hex2bin(bytes hexstr)
cpdef long bin2int(bytearray binstr)
cpdef long hex2int(bytearray binstr)
cpdef unsigned char df(bytes msg)
cpdef long crc(bytes msg, bint encode=*)
cpdef long floor(double x)
cpdef str icao(bytes msg)
cpdef bint is_icao_assigned(bytes icao)
cpdef int typecode(bytes msg)
cpdef int cprNL(double lat)
cpdef str idcode(bytes msg)
cpdef int altcode(bytes msg)
cdef bytes data(bytes msg)
cpdef bint allzeros(bytes msg)

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@ -1,4 +1,3 @@
# cython: language_level=3
cimport cython
@ -143,14 +142,14 @@ cpdef long crc(bytes msg, bint encode=False):
cpdef int floor(float x):
cpdef long floor(double x):
"""Mode-S floor function.
Defined as the greatest integer value k, such that k <= x
For example: floor(3.6) = 3 and floor(-3.6) = -4
"""
return <int> c_floor(x)
return <long> c_floor(x)
cpdef str icao(bytes msg):
"""Calculate the ICAO address from an Mode-S message.
@ -228,7 +227,7 @@ cpdef int typecode(bytes msg):
return bin2int(tcbin[0:5])
@cython.cdivision(True)
cpdef int cprNL(int lat):
cpdef int cprNL(double lat):
"""NL() function in CPR decoding."""
if lat == 0:
@ -241,9 +240,9 @@ cpdef int cprNL(int lat):
return 1
cdef int nz = 15
cdef float a = 1 - cos(pi / (2 * nz))
cdef float b = cos(pi / 180.0 * fabs(lat)) ** 2
cdef float nl = 2 * pi / (acos(1 - a / b))
cdef double a = 1 - cos(pi / (2 * nz))
cdef double b = cos(pi / 180.0 * fabs(lat)) ** 2
cdef double nl = 2 * pi / (acos(1 - a / b))
NL = floor(nl)
return NL
@ -359,7 +358,7 @@ cpdef int altcode(bytes msg):
cdef int gray2alt(bytearray codestr):
cpdef int gray2alt(bytearray codestr):
cdef bytearray gc500 = codestr[:8]
cdef int n500 = gray2int(gc500)

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@ -20,7 +20,8 @@ from setuptools.extension import Extension
from Cython.Build import cythonize
extensions = [
Extension("pyModeS.c_decoder.common", ["pyModeS/c_decoder/common.pyx"])
Extension("pyModeS.c_decoder.common", ["pyModeS/c_decoder/common.pyx"]),
Extension("pyModeS.c_decoder.bds.bds05", ["pyModeS/c_decoder/bds/bds05.pyx"]),
]