FGFS-4.1/gr-air-modes
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CPR test case hugely expanded. Found bug in global decoding in the Southern Hemisphere. Haven't fixed the bug yet.

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This commit is contained in:
Nick Foster 2012-06-15 19:34:03 -07:00
parent f9026feb7f
commit c6ab762ee0
2 changed files with 38 additions and 31 deletions
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5
apps/get_correlated_records.py
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@ -1,6 +1,5 @@
#!/usr/bin/env python #!/usr/bin/env python
from modes_parse import modes_parse from air_modes import modes_parse, mlat
import mlat
import numpy import numpy
import sys import sys
@ -10,7 +9,7 @@ import sys
#sfoutfile = open("sfout.txt", "w") #sfoutfile = open("sfout.txt", "w")
#rudioutfile = open("rudiout.txt", "w") #rudioutfile = open("rudiout.txt", "w")
sfparse = modes_parse([37.762236,-122.442525]) sfparse = modes_parse.modes_parse([37.762236,-122.442525])
sf_station = [37.762236,-122.442525, 100] sf_station = [37.762236,-122.442525, 100]
mv_station = [37.409348,-122.07732, 100] mv_station = [37.409348,-122.07732, 100]

64
python/cpr.py
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@ -1,5 +1,6 @@
#!/usr/bin/env python
# #
# Copyright 2010 Nick Foster # Copyright 2010, 2012 Nick Foster
# #
# This file is part of gr-air-modes # This file is part of gr-air-modes
# #
@ -19,8 +20,6 @@
# Boston, MA 02110-1301, USA. # Boston, MA 02110-1301, USA.
# #
#!/usr/bin/env python
#from string import split, join #from string import split, join
#from math import pi, floor, cos, acos #from math import pi, floor, cos, acos
import math, time import math, time
@ -56,8 +55,10 @@ def nl_eo(declat_in, ctype):
return nl(declat_in) - ctype return nl(declat_in) - ctype
def nl(declat_in): def nl(declat_in):
if declat_in == 0: if declat_in >= 87.0:
declat_in = 0.01 declat_in = 86.999999999
if declat_in <= -87.0:
declat_in = -86.999999999
return math.floor( (2.0*math.pi) * pow(math.acos(1.0- (1.0-math.cos(math.pi/(2.0*latz))) / pow( math.cos( (math.pi/180.0)*abs(declat_in) ) ,2.0) ),-1.0)) return math.floor( (2.0*math.pi) * pow(math.acos(1.0- (1.0-math.cos(math.pi/(2.0*latz))) / pow( math.cos( (math.pi/180.0)*abs(declat_in) ) ,2.0) ),-1.0))
def dlon(declat_in, ctype, surface): def dlon(declat_in, ctype, surface):
@ -264,34 +265,41 @@ def cpr_encode(lat, lon, ctype, surface):
return (yz, xz) #lat, lon return (yz, xz) #lat, lon
if __name__ == '__main__': if __name__ == '__main__':
from modes_parse import * import sys, random
import sys
my_location = [37.76225, -122.44254] rounds = 100
threshold = 1e-3 #0.001 deg lat/lon
#this accuracy is highly dependent on latitude, since at high
#latitudes the corresponding error in longitude is greater
decoder = cpr_decoder(None)
shortdata = long(sys.argv[1], 16) for i in range(0, rounds):
longdata = long(sys.argv[2], 16) ac_lat = random.uniform(-87,87)
parity = long(sys.argv[3], 16) ac_lon = random.uniform(-180,180)
ecc = long(sys.argv[4], 16)
parser = modes_parse(my_location) #encode that position
(evenenclat, evenenclon) = cpr_encode(ac_lat, ac_lon, False, False)
(oddenclat, oddenclon) = cpr_encode(ac_lat, ac_lon, True, False)
[altitude, decoded_lat, decoded_lon, rnge, bearing] = parser.parseBDS06(shortdata, longdata, parity, ecc) #perform a global decode
icao = random.randint(0, 0xffffff)
evenpos = decoder.decode(icao, evenenclat, evenenclon, False, False)
if evenpos != [None, None, None, None]:
raise Exception("CPR test failure: global decode with only one report")
(odddeclat, odddeclon, rng, brg) = decoder.decode(icao, oddenclat, oddenclon, True, False)
if decoded_lat is not None: if odddeclat is None: #boundary straddle, just move on
print "Altitude: %i\nLatitude: %.6f\nLongitude: %.6f\nRange: %.2f\nBearing: %i\n" % (altitude, decoded_lat, decoded_lon, rnge, bearing,) continue
print "Decomposing...\n" if abs(odddeclat - ac_lat) > threshold or abs(odddeclon - ac_lon) > threshold:
print "Global decode error: Lat: %f Lon: %f Decoded lat: %f lon: %f" % (ac_lat, ac_lon, odddeclat, odddeclon)
#raise Exception("CPR test failure: global decode error greater than threshold")
subtype = (longdata >> 51) & 0x1F; (evendeclat, evendeclon) = cpr_resolve_local([ac_lat, ac_lon], [evenenclat, evenenclon], False, False)
if abs(evendeclat - ac_lat) > threshold or abs(evendeclon - ac_lon) > threshold:
print "Local decode error: Lat: %f Lon: %f Decoded lat: %f lon: %f" % (ac_lat, ac_lon, evendeclat, evendeclon)
#raise Exception("CPR test failure: local decode error greater than threshold")
encoded_lon = longdata & 0x1FFFF print "CPR test successful."
encoded_lat = (longdata >> 17) & 0x1FFFF
cpr_format = (longdata >> 34) & 1
enc_alt = (longdata >> 36) & 0x0FFF
[cpr_lat, cpr_lon] = cpr_resolve_local(my_location, [encoded_lat, encoded_lon], cpr_format, 1)
print "Subtype: %i\nEncoded longitude: %x\nEncoded latitude: %x\nCPR format: %i\nEncoded altitude: %x\n" % (subtype, encoded_lon, encoded_lat, cpr_format, enc_alt,)
print "Pos: %.6f %.6f" % (cpr_lat, cpr_lon)