ืืขืื ืืืืจ. ืืืกืืึธืืข ืึทืืขืืขื ืืืืก ืืคึผืืืช ืึทืืึธื ืืืืขืื ื ืึธืืขืจ ืืขืืขื ืึทืืืขืง ืงืจืืืื ืึธืืขืจ ืคืจืขื ืื ืืืืฃ ืึท ืคืืึทื ืืขืืืืื ื ืื ืคืจืื Flightradar24 ืืื ืกื. ืืึธืก ืืื ืึท ืืืืขืจ ืืึทืงืืืขื ืืืขื ืฆื ืฉืคึผืืจ ืื ืฉืืขืืข ืคืื โโืื ืขืจืงืจืึทืคื ืืื ืคืึทืงืืืฉ ืฆืืื.
ะ ืืขืจ ืคึผืจืื ืฆืืคึผ ืคืื ืึธืคึผืขืจืึทืฆืืข ืคืื โโืึทืืึท ืึทื ืึธื ืืืื ืืื ืกื ืืื ืืืกืงืจืืืื. ืืืฆื ืืืจ ืืืขืื ืืืื ืืืืึทืืขืจ ืืื ืืขืคึฟืื ืขื ืืืืก ืืืึธืก ืืึทืื ืืขื ืขื ืืจืึทื ืกืืืืืขื ืืื ืืืงืืืขื ืคืื ืื ืขืจืงืจืึทืคื ืฆื ืื ืจืืกืืืืื ื ืกืืึทื ืฆืืข, ืืื ืืขืงืึธืืข ืขืก ืืื ืืื ืคึผืืืืึธื.
ืืขืฉืืืืข
ืงืืืจ, ืขืจืงืจืึทืคื ืืึทืื ืืขื ืขื ื ืืฉื ืฉืขืจื ืคึฟืึทืจ ืืืืขืจื ืฆื ืืขื ืืืืฃ ืืืืขืจ ืกืืึทืจืืคืึธื ืขืก. ืื ืกืืกืืขื ืืืขืจื ืื ืืขืจืืคื ADS-B (ืืืืืืืืืืฉืข ืืคืืขื ืืืืข ืกืขืจืืืืืืึทื ืก โ ืืจืึธืืงืึทืกื), ืืื ืืืขืจื ืืขื ืืฆื ืฆื ืืืืืืืืืืฉ ืืืืขืจืฉืืงื ืืื ืคืืจืืืฆืืข ืืืืขืจ ืื ืขืจืืคืืื ืฆืื ืงืื ืืจืื ืฆืขื ืืขืจ - ืืืจ ืืืืขื ืืืคืืฆืืจ, ืงืืืจืืื ืึทืืขืก, ืจืืืืื ื, ืืืืงืืึทื, ืืืื ืืื ืื ืืขืจืข ืืึทืื ืืขื ืขื ืืจืึทื ืกืืืืืขื. ืืื ืึทืืขืจ, ืืืืืขืจ ืื ืึทืืืืขื ื ืคืื ืึทืืึท ืกืืกืืขืืขื, ืื ืืืกืคึผืึทืืฉืขืจ ืงืขื ื ืึธืจ ืืขื ืึท ืคึผืื ืงื ืืืืฃ ืื ืจืึทืืึทืจ. ืืืก ืืื ื ืืฉื ืืขืืืขื ืืขื ืื ืืืขื ืขืก ืืขื ืขื ืืขืืืขื ืฆืืคืื ืขืจืืคืืื ืขื.
ืืขืงื ืืงืื, ADS-B ืืืฉืืืื ืคืื ืึท ืขืจืงืจืึทืคื ืืจืึทื ืกืืืืขืจ ืืืึธืก ืคึผืืจืืึทืืืงืื ืกืขื ืื ืคึผืึทืงืืฅ ืืื ืืื ืคึฟืึธืจืืึทืฆืืข ืืื ืึท ืคืขืจืื ืืืื ืึธืคืืงืืึทื ืคืื 1090 ืืื (ืขืก ืืขื ืขื ืื ืืขืจืข ืืึธืืขืก, ืึธืืขืจ ืืื ืืขื ืขื ื ืืฉื ืึทืืื ืืฉืืงืึทืืืข ืคึฟืึทืจ ืืื ืื, ืืืืึทื ืื ืงืึธืืึธืจืืึทื ืึทืฅ ืืขื ืขื ืืจืึทื ืกืืืืืขื ืืืืื ืืึธ). ืคืื ืงืืจืก, ืืื ืึทืืืฉืึทื ืฆื ืื ืืจืึทื ืกืืืืขืจ, ืขืก ืืื ืืืื ืึท ืืคื ืขืืขืจ ืขืจืืขืฅ ืืื ืื ืึทืขืจืึธืคึผืึธืจื, ืึธืืขืจ ืคึฟืึทืจ ืืื ืื, ืืื ื ืืฆืขืจืก, ืืื ืืืขืจ ืืืืืขื ืข ืืคื ืขืืขืจ ืืื ืคืื ืืื ืืขืจืขืก.
ืืืจื ืืขื ืืืขื, ืคึฟืึทืจ ืคืึทืจืืืืึทื, ืืขืจ ืขืจืฉืืขืจ ืึทืืึท ืกืืกืืขื, ืึทืืจื ืึทืื ืจืึทืืึทืจืืึธืงืก, ืืืืืื ื ืคึฟืึทืจ ืคึผืจืึธืกื ื ืืฆืขืจืก, ืืจืืืก ืืื 2007 ืืื ืงืึธืกืื ืืืขืื $ 900, ืืื ืึท ืึทืืึธื ืขืืขื ื ืฆื ื ืขืฅ ืืึทืืื ืื ืืก ืงืึธืก ืืืขืื $ 250 ืคึผืขืจ ืืึธืจ.
ืชืืืืืช ืคืื ืื ืขืจืฉืืข ืจืืกืืฉ ืึธืื ืขืจื ืงืขื ืขื ืืืื ืืืืขื ืขื ืืืืฃ ืืขื ืคืึธืจืื . ืืืฆื ืึทื RTL-SDR ืจืืกืืืืขืจื ืืึธืื ืืืขืจื ืืึทืกืืืืื ืื ืืืฆื, ืึท ืขื ืืขื ืืืื ืงืขื ืขื ืืืื ืคืืจืืืืื ืคึฟืึทืจ $ 30, ืืขืจ ืืืขืื ืืขื ืืื ืืขืืืขื ืืื . ืืืจ ืืืขืื ืืืื ืฆื ืื ืคึผืจืึธืืึธืงืึธื ืืื - ืืึธืืืจ ืืขื ืืื ืขืก ืึทืจืืขื.
ืกืืื ืึทื ืึธืคึผืืจืึธื
ืขืจืฉืืขืจ, ืืขืจ ืกืืื ืึทื ืืืื ืืืื ืจืขืงืึธืจืืขื. ืืขืจ ืืื ืฆืขืจ ืกืืื ืึทื ืืื ืึท ืืขืืืืขืจ ืคืื ืืืืื 120 ืืืงืจืึธืกืขืงืึธื ืืก, ืึทืืื ืฆื ืงืึทืืคืขืจืืึทืืื ืืืกืึทืกืขืืืึทื ืืืึทื ืงืึทืืคึผืึธืื ืึทื ืฅ, ืึท SDR ืืคื ืขืืขืจ ืืื ืึท ืืืกืืขืจืื ื ืงืืจืก ืคืื ืืืึท ืืื ืืกืืขืจ 5 ืืื ืืื ืืืืืืจืึทืืึทื.
ื ืึธื ืจืขืงืึธืจืืื ื, ืืืจ ืืึทืงืืืขื ืึท ืืืึทืื ืืขืงืข ืืื ืึท ืืืกืืขืจืื ื ืงืืจืก ืคืื 5000000 ืกืึทืืคึผืึทืื / ืกืขืง, 30 ืกืขืงืื ืืขืก ืคืื ืึทืืึท ืึท ืจืขืงืึธืจืืื ื "ืืืขืื" ืืืขืื 500 ืื. ืคืื ืงืืจืก, ืขืก ืืื ืึทืจืืืกืืขืืืึธืจืคื ืฆื ืืขืจื ืฆื ืขืก ืืื ืึท ืืขืืืข ืฉืคึผืืืขืจ - ืื ืืขืงืข ืึผืืื ืงืืื ืืขืืื ื, ืึธืืขืจ ืึท ืืืืึทื ืืืืืฉืึทืืืืื ืจืึทืืืึธ ืกืืื ืึทื - ืืึธืก ืืื ืืื ืืืืืืืืืจื Defined Radio ืึทืจืืขื.
ืืืจ ืืืขืื ืขืคึฟืขื ืขื ืืื ืคึผืจืึธืฆืขืก ืื ืืขืงืข ื ืืฆื Python. ืืขื ืข ืืืืก ืืืืื ืฆื ืขืงืกืคึผืขืจืืืขื ื ืืืืฃ ืืืืขืจ ืืืืื ืงืขื ืขื ืืจืืคืงืืคืืข ืึท ืืืึทืฉืคึผืื ืจืขืงืึธืจืืื ื .
ืืึธืืืจ ืืจืืคืงืืคืืข ืื ืืขืงืข ืืื ืืขื ืืืึธืก ืืื ืื.
from scipy.io import wavfile
import matplotlib.pyplot as plt
import numpy as np
fs, data = wavfile.read("adsb_20190311_191728Z_1090000kHz_RF.wav")
data = data.astype(float)
I, Q = data[:, 0], data[:, 1]
A = np.sqrt(I*I + Q*Q)
plt.plot(A)
plt.show()
ืจืขืืืืืึทื: ืืืจ ืืขื ืงืืึธืจ "ืืืคึผืึทืืกืื" ืงืขืื ืืขื ืืื ืืขืจืืจืื ื ืคืื ืจืึทืฉ.
ืืขืืขืจ "ืืืคึผืึทืืก" ืืื ืึท ืกืืื ืึทื, ืื ืกืืจืืงืืืจ ืคืื ืืืึธืก ืืื ืงืืืจ ืงืขื ืืืง ืืืื ืืืจ ืคืึทืจืืจืขืกืขืจื ืื ืืึทืืืึธืืข ืืืืฃ ืื ืืจืึทืคืืง.
ืืื ืืืจ ืงืขื ืขื ืืขื, ืื ืืืื ืืื ืืึทื ืฅ ืงืึธื ืกืืกืืขื ื ืืื ืืืึธืก ืืื ืืขืืขืื ืืื ืื ืืึทืฉืจืืึทืืื ื ืืืืื. ืืืจ ืงืขื ืขื ืึธื ืืืืื ืคึผืจืึทืกืขืกืื ื ืื ืืึทืื.
ืืืงืึธืืืื ื
ืขืจืฉืืขืจ, ืืืจ ืืึทืจืคึฟื ืฆื ืืึทืงืืืขื ืึท ืืืกื ืืืึทื. ืืขืจ ืกืืื ืึทื ืืื ืืื ืงืึธืืขื ืืื ืืึทื ืืฉืขืกืืขืจ ืงืึธืืืจืื ื:
ืขืก ืืื ืืจืื ื ืฆื ืืึทืงืืืขื ืคืึทืงืืืฉ "0" ืืื "1" ืคึฟืื ืื ืืืจืื ืืืืืง ืืื ื ืืืึทืื.
bits_str = ""
for p in range(8):
pos = start_data + bit_len*p
p1, p2 = A[pos: pos + bit_len/2], A[pos + bit_len/2: pos + bit_len]
avg1, avg2 = np.average(p1), np.average(p2)
if avg1 < avg2:
bits_str += "0"
elif avg1 > avg2:
bits_str += "1"
ืื ืกืืจืืงืืืจ ืคืื ืื ืกืืื ืึทื ืืื ืืื ืืื ืืืื:
ืืื ืก ืงืืง ืืื ืื ืคืขืืืขืจ ืืื ืืขืจ ืืขืืึทื.
DF (ืืึทืื ืืื ืง ืคึฟืึธืจืืึทื, 5 ืืืื) - ืืืคืืื ื ืื ืึธื ืืึธื ืืืคึผ. ืขืก ืืขื ืขื ืขืืืขืืข ืืืืคึผืก:
()
ืืืจ ืืขื ืขื ืืืืื ืืื ืืขืจืขืกืืจื ืืื ืื DF17 ืืืคึผ, ืืืืึทื ืขืก ืึผืืื ืื ืงืึธืืึธืจืืึทื ืึทืฅ ืคืื ืื ืขืจืงืจืึทืคื.
ืืงืึทืึธ (24 ืืืฅ) - ืื ืืื ืืขืจื ืึทืฆืืึธื ืึทืืข ืืื ืฆืืง ืงืึธื ืคืื ืื ืขืจืงืจืึทืคื. ืืืจ ืงืขื ืขื ืงืึธื ืืจืึธืืืจื ืื ืขืจืงืจืึทืคื ืืืจื ืืืึทื ืงืึธื (ืฆืื ืืึทืืืืขืจื ืืึธื ืืขืจ ืืืืจ ืืืืคืืขืืขืจื ืฆื ืืขืจืืืึทื ืืืงื ืื ืืึทืืึทืืืืก, ืึธืืขืจ ืขืก ืืื ื ืึธื ืืึทืืืึทืืืง). ืคึฟืึทืจ ืืืึทืฉืคึผืื, ืคึฟืึทืจ ืื ืงืึธื 3c5ee2 ืืืจ ืืึธืื ืื ืคืืืืขื ืืข ืืื ืคึฟืึธืจืืึทืฆืืข:
ืจืขืืึทืืืจื: ืืื ืื ืืึทืฉืจืืึทืืื ื ืคืื ืื ICAO ืงืึธื ืืื ืืขืืขืื ืืื ืืขืจ ืืขืืึทื, ืืื ืจืขืงืึธืืขื ืืืจื ืึทื ืืขื ืข ืืืืก ืืขื ืขื ืืื ืืขืจืขืกืืจื ืืืืขื ืขื ืขืก.
ืืึทืืข (56 ืึธืืขืจ 112 ืืืฅ) - ืื ืคืึทืงืืืฉ ืืึทืื ืืืึธืก ืืืจ ืืืขืื ืืขืงืึธืืข. ืืขืจ ืขืจืฉืืขืจ 5 ืืืื ืคืื ืืึทืื ืืขื ืขื ืื ืคืขืื ืืืคึผ ืงืึธืื ืืื ืื ืกืืืืืคึผืข ืคืื โโืื ืกืืึธืจื ืืึทืื (ื ืื ืฆื ืืืื ืฆืขืืืฉื ืืื DF). ืขืก ืืขื ืขื ืึท ืืืกื ืคืื ืื ืืืืคึผืก:
()
ืืื ืก ืงืืง ืืืึท ืขืืืขืืข ืืืืฉืคืืื ืคืื ืคึผืึทืงืึทืืืฉืึทื.
ืขืจืงืจืึทืคื ืืขืืืืืืึทืฆืืข
ืืืื ืขืจื ืืืืฉืคึผืื:
00100 011 000101 010111 000111 110111 110001 111000
ืืึทืื ืคืขืืืขืจ:
+------+------+------+------+------+------+------+------+------+------+
| TC,5 | EC,3 | C1,6 | C2,6 | C3,6 | C4,6 | C5,6 | C6,6 | C7,6 | C8,6 |
+------+------+------+------+------+------+------+------+------+------+
TC = 00100b = 4, ืืขืืขืจ ืืึทืจืึทืงืืขืจ C1-C8 ืึผืืื ืงืึธืืื ืงืึธืจืึทืกืคึผืึทื ืืื ื ืฆื ืื ืืืกืื ืืื ืื ืฉืืจืืงื:
#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_##############0123456789######
ื ืึธื ืืืงืึธืืืึทื ืื ืฉืืจืืงื, ืขืก ืืื ืืจืื ื ืฆื ืืึทืงืืืขื ืื ืขืจืงืจืึทืคื ืงืึธื: EWG7184
symbols = "#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_###############0123456789######"
code_str = ""
for p in range(8):
c = int(bits_str[8 + 6*p:8 + 6*(p + 1)], 2)
code_str += symbols[c]
print("Aircraft Identification:", code_str.replace('#', ''))
ืขืจืืึธืจื ืฉืืขืืข
ืืืื ืึทืืฅ ืืื ืคึผืฉืื ืืื ืื ื ืึธืืขื, ืืื ืื ืงืึธืืึธืจืืึทื ืึทืฅ ืขืก ืืื ืืขืจ ืงืึธืืคึผืืืฆืืจื. ืืื ืืขื ืขื ืืจืึทื ืกืืืืืขื ืืื 2x, ืืึธืื ืข ืืื ืืคืืื ืจืึธืืขื. ืคืขืื ืงืึธื ืืง = 01011ื = 11.
ื ืืืืฉืคึผืื ืคืื ืืคืืื ืืื ืืึธืื ืข ืคึผืึทืงืืฅ:
01011 000 000101110110 00 10111000111001000 10000110101111001
01011 000 000110010000 01 10010011110000110 10000011110001000
ืืขืจ ืืขืืฉืื ืคืื ืื ืงืึธืืึธืจืืึทื ืึทืฅ ืืื ื ืขืื ืึธืจื ืืืื ืึท ืืึทื ืฅ ืืจืืงื ืคืึธืจืืืืข:
()
ืืื ืืื ื ืืฉื ืึท GIS ืืืืืข, ืึทืืื ืืื ืืึธื ื ืื ืืืืกื ืืื ืขืก ืงืืื ืคืื. ืืืขืจ ืืืืืกื, ืฉืจืืื ืืื ืื ืืึทืืขืจืงืื ืืขื.
ืืืื ืืื ืืขืจืขืื ื ืืื ืกืืืคึผืืขืจ - ืืืคึผืขื ืืื ื ืืืืฃ ืื ืกืคึผืขืฆืืคืืฉ ืืืกื, ืขืก ืงืขื ืขื ืืืื ืจืขืคึผืจืืืขื ืืื ืืื ืึท ืงืืืคื ืคืื 25 ืึธืืขืจ 100 ืคึฟืืก.
ืึทืืจืืึธืจื ืข ืืืขืืึธืกืืื
ืคึผืึทืงืึทื ืืื TC = 19. ืื ืืฉืืงืึทืืืข ืืึทื ืืึธ ืืื ืึทื ืื ืืืืงืืึทื ืงืขื ืขื ืืืื ืืืืืข ืคึผืื ืืืขื, ืจืขืืึทืืืื ืฆื ืืขืจ ืขืจื (ืืจืึธืื ื ืกืคึผืื), ืืื ืืืคื, ืืขืืืกืื ืืืจื ืื ืขืจืงืจืึทืคื ืกืขื ืกืขืจ (ืึทืืจืกืคึผืขื). ืคืืืข ืคืึทืจืฉืืืขื ืข ืคืขืืืขืจ ืืขื ืขื ืืืื ืืืจืืืขืืื ืืขื:
()
ืกืึธืฃ
ืืื ืืืจ ืงืขื ืขื ืืขื, ืึทืืก-ื ืืขืื ืึธืืึธืืืข ืืื ืืขืืืืจื ืึท ืืฉืืงืึทืืืข ืกืืืืืืึธืืกืึทืก, ืืืขื ืึท ื ืึธืจืืึทื ืืื ื ืืฆืืง ื ืื ืืืืื ืคึฟืึทืจ ืคึผืจืึธืคืขืกืกืืึธื ืึทืืก, ืึธืืขืจ ืืืื ืคึฟืึทืจ ืคึผืจืึธืกื ื ืืฆืขืจืก. ืืืขืจ ืคืื ืงืืจืก, ืื ืฉืืืกื ืจืึธืืข ืืื ืืขื ืืื ืืขืืืขื ืคึผืืืึทืขื ืืืจื ืื ืืฉืืคึผืขืจ ืืขืื ืึธืืึธืืืข ืคืื โโืืืืืืึทื SDR ืจืึทืกืืืืขืจื, ืืืึธืก ืึทืืึทืื ืื ืืืื ืฆื ืืืฉ "ืคึฟืึทืจ ืึท ืคึผืขื ื" ืืึทืงืืืขื ืกืืื ืึทืื ืืื ืึท ืึธืคืืงืืึทื ืืขืืขืจ ืึท ืืืืึทืืขืจืฅ.
ืืื ืืขืจ ื ืึธืจืืึทื ืืื, ืคืื ืงืืจืก, ืคืื ืืขืจ. ืื ืืื ืืขืจืขืกืืจื ืงืขื ืขื ืืขื ืื PDF ืืืืฃ ืืขื ืืืึทื ืึธืืขืจ ืืึทืืืื ืฉืืื ืืขืจืืื ื ืืืืื .
ืขืก ืืื ืึทื ืืืืงืื ืึทื ืึทืืข ืคืื โโโโืื ืืืืื ืืืขื ืืืื ื ืืฆืืง ืคึฟืึทืจ ืคืืืข, ืึธืืขืจ ืืื ืืื ืืกืืขืจ ืืขืจ ืืขื ืขืจืึทื ืืขืืึทื ืง ืคืื ืืื ืขืก ืึทืจืืขื, ืืื ืืึธืคึฟื, ืืืืืื.
ืืืจื ืืขื ืืืขื, ืึท ืคืึทืจืืืง ืคึผืืืืึธื ืืืงืึธืืืขืจ ืืื ืฉืืื ืืืืืกืฅ, ืืืจ ืงืขื ืขื ืืขืจื ืขื ืขืก . ืืื ืึธืื ืขืจื ืคืื SDR ืจืืกืืืืขืจื ืงืขื ืขื ืึทืกืขืืืึทื ืืื ืืืืคื ืึท ืคืึทืจืืืง ืึทืืก-ื ืืืงืึธืืืขืจ , ืืึธืก ืืื ืืืกืงืึทืกื ืืื ืืขืจ ืืขืืึทื ืืื .
ืืขืจ ืืงืืจ ืงืึธื ืคืื ืื ืคึผืึทืจืกืขืจ ืืืกืงืจืืืื ืืื ืืขื ืึทืจืืืงื ืืื ืืขืืขืื ืืื ืืขืจ ืื ืฉื ืืึทืื. ืืึธืก ืืื ืึท ืคึผืจืึธืืข ืืืืฉืคึผืื ืืืึธืก ืืื ื ืืฉื ืคืึทืจืืืื ืฆื ืืืื ืคึผืจืึธืืืงืฆืืข, ืึธืืขืจ ืขืคึผืขืก ืึทืจืืขื ืืื ืขืก, ืืื ืืื ืงืขื ืขื ืคึผืึทืจืก ืื ืืขืงืข ืจืขืงืึธืจืืขื ืืืืื.
ืืงืืจ ืงืึธื (Python)
from __future__ import print_function
from scipy.io import wavfile
from scipy import signal
import matplotlib.pyplot as plt
import numpy as np
import math
import sys
def parse_message(data, start, bit_len):
max_len = bit_len*128
A = data[start:start + max_len]
A = signal.resample(A, 10*max_len)
bits = np.zeros(10*max_len)
bit_len *= 10
start_data = bit_len*8
# Parse first 8 bits
bits_str = ""
for p in range(8):
pos = start_data + bit_len*p
p1, p2 = A[pos: pos + bit_len/2], A[pos + bit_len/2: pos + bit_len]
avg1, avg2 = np.average(p1), np.average(p2)
if avg1 < avg2:
bits_str += "0"
elif avg1 > avg2:
bits_str += "1"
df = int(bits_str[0:5], 2)
# Aircraft address (db - https://junzis.com/adb/?q=3b1c5c )
bits_str = ""
for p in range(8, 32):
pos = start_data + bit_len * p
p1, p2 = A[pos: pos + bit_len / 2], A[pos + bit_len / 2: pos + bit_len]
avg1, avg2 = np.average(p1), np.average(p2)
if avg1 < avg2:
bits_str += "0"
elif avg1 > avg2:
bits_str += "1"
# print "Aircraft address:", bits_str, hex(int(bits_str, 2))
address = hex(int(bits_str, 2))
# Filter specific aircraft (optional)
# if address != "0x3c5ee2":
# return
if df == 16 or df == 17 or df == 18 or df == 19 or df == 20 or df == 21:
# print "Pos:", start, "DF:", msg_type
# Data (56bit)
bits_str = ""
for p in range(32, 88):
pos = start_data + bit_len*p
p1, p2 = A[pos: pos + bit_len/2], A[pos + bit_len/2: pos + bit_len]
avg1, avg2 = np.average(p1), np.average(p2)
if avg1 < avg2:
bits_str += "0"
# bits[pos + bit_len / 2] = 50
elif avg1 > avg2:
bits_str += "1"
# http://www.lll.lu/~edward/edward/adsb/DecodingADSBposition.html
# print "Data:"
# print bits_str[:8], bits_str[8:20], bits_str[20:22], bits_str[22:22+17], bits_str[39:39+17]
# Type Code:
tc, ec = int(bits_str[:5], 2), int(bits_str[5:8], 2)
# print("DF:", df, "TC:", tc)
# 1 - 4 Aircraft identification
# 5 - 8 Surface position
# 9 - 18 Airborne position (w/ Baro Altitude)
# 19 Airborne velocities
if tc >= 1 and tc <= 4: # and (df == 17 or df == 18):
print("Aircraft address:", address)
print("Data:")
print(bits_str[:8], bits_str[8:14], bits_str[14:20], bits_str[20:26], bits_str[26:32], bits_str[32:38], bits_str[38:44])
symbols = "#ABCDEFGHIJKLMNOPQRSTUVWXYZ#####_###############0123456789######"
code_str = ""
for p in range(8):
c = int(bits_str[8 + 6*p:8 + 6*(p + 1)], 2)
code_str += symbols[c]
print("Aircraft Identification:", code_str.replace('#', ''))
print()
if tc == 11:
print("Aircraft address:", address)
print("Data: (11)")
print(bits_str[:8], bits_str[8:20], bits_str[20:22], bits_str[22:22+17], bits_str[39:39+17])
# Bit 22 contains the F flag which indicates which CPR format is used (odd or even)
# First frame has F flag = 0 so is even and the second frame has F flag = 1 so odd
# f = bits_str[21:22]
# print("F:", int(f, 2))
# Altitude
alt1b = bits_str[8:20]
if alt1b[-5] == '1':
bits = alt1b[:-5] + alt1b[-4:]
n = int(bits, 2)
alt_ft = n*25 - 1000
print("Alt (ft)", alt_ft)
# lat_dec = int(bits_str[22:22+17], 2)
# lon_dec = int(bits_str[39:39+17], 2)
# print("Lat/Lon:", lat_dec, lon_dec)
# http://airmetar.main.jp/radio/ADS-B%20Decoding%20Guide.pdf
print()
if tc == 19:
print("Aircraft address:", address)
print("Data:")
# print(bits_str)
print(bits_str[:5], bits_str[5:8], bits_str[8:10], bits_str[10:13], bits_str[13] ,bits_str[14:24], bits_str[24], bits_str[25:35], bits_str[35:36], bits_str[36:65])
subtype = int(bits_str[5:8], 2)
# https://mode-s.org/decode/adsb/airborne-velocity.html
spd, hdg, rocd = -1, -1, -1
if subtype == 1 or subtype == 2:
print("Velocity Subtype 1: Ground speed")
v_ew_sign = int(bits_str[13], 2)
v_ew = int(bits_str[14:24], 2) - 1 # east-west velocity
v_ns_sign = int(bits_str[24], 2)
v_ns = int(bits_str[25:35], 2) - 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
if subtype == 3:
print("Subtype Subtype 3: Airspeed")
hdg = int(bits_str[14:24], 2)/1024.0*360.0
spd = int(bits_str[25:35], 2)
vr_sign = int(bits_str[36], 2)
vr = int(bits_str[36:45], 2)
rocd = -1*vr if vr_sign else vr # rate of climb/descend
print("Speed (kts):", spd, "Rate:", rocd, "Heading:", hdg)
print()
# print()
def calc_coordinates():
def _cprN(lat, is_odd):
nl = _cprNL(lat) - is_odd
return nl if nl > 1 else 1
def _cprNL(lat):
try:
nz = 15
a = 1 - math.cos(math.pi / (2 * nz))
b = math.cos(math.pi / 180.0 * abs(lat)) ** 2
nl = 2 * math.pi / (math.acos(1 - a/b))
return int(math.floor(nl))
except:
# happens when latitude is +/-90 degree
return 1
def floor_(x):
return int(math.floor(x))
lat1b, lon1b, alt1b = "10111000111010011", "10000110111111000", "000101111001"
lat2b, lon2b, alt2b = "10010011101011100", "10000011000011011", "000101110111"
lat1, lon1, alt1 = int(lat1b, 2), int(lon1b, 2), int(alt1b, 2)
lat2, lon2, alt2 = int(lat2b, 2), int(lon2b, 2), int(alt2b, 2)
# 131072 is 2^17, since CPR lat and lon are 17 bits each
cprlat_even, cprlon_even = lat1/131072.0, lon1/131072.0
cprlat_odd, cprlon_odd = lat2/131072.0, lon2/131072.0
print(cprlat_even, cprlon_even)
j = floor_(59*cprlat_even - 60*cprlat_odd)
print(j)
air_d_lat_even = 360.0 / 60
air_d_lat_odd = 360.0 / 59
# Lat
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
# Lon
ni = _cprN(lat_even, 0)
m = floor_(cprlon_even * (_cprNL(lat_even)-1) - cprlon_odd * _cprNL(lat_even) + 0.5)
lon = (360.0 / ni) * (m % ni + cprlon_even)
print("Lat", lat_even, "Lon", lon)
# Altitude
# Q-bit (bit 48) indicates whether the altitude is encoded in multiples of 25 or 100 ft (0: 100 ft, 1: 25 ft)
# The value can represent altitudes from -1000 to +50175 ft.
if alt1b[-5] == '1':
bits = alt1b[:-5] + alt1b[-4:]
n = int(bits, 2)
alt_ft = n*25 - 1000
print("Alt (ft)", alt_ft)
fs, data = wavfile.read("adsb_20190311_191728Z_1090000kHz_RF.wav")
T = 1/fs
print("Sample rate %f MS/s" % (fs / 1e6))
print("Cnt samples %d" % len(data))
print("Duration: %f s" % (T * len(data)))
data = data.astype(float)
cnt = data.shape[0]
# Processing only part on file (faster):
# cnt = 10000000
# data = data[:cnt]
print("Processing I/Q...")
I, Q = data[:, 0], data[:, 1]
A = np.sqrt(I*I + Q*Q)
bits = np.zeros(cnt)
# To see scope without any processing, uncomment
# plt.plot(A)
# plt.show()
# sys.exit(0)
print("Extracting signals...")
pos = 0
avg = 200
msg_start = 0
# Find beginning of each signal
while pos < cnt - 16*1024:
# P1 - message start
while pos < cnt - 16*1024:
if A[pos] < avg and A[pos+1] > avg and pos - msg_start > 1000:
msg_start = pos
bits[pos] = 100
pos += 4
break
pos += 1
start1, start2, start3, start4 = msg_start, 0, 0, 0
# P2
while pos < cnt - 16*1024:
if A[pos] < avg and A[pos+1] > avg:
start2 = pos
bits[pos] = 90
pos += 1
break
pos += 1
# P3
while pos < cnt - 16*1024:
if A[pos] < avg and A[pos+1] > avg:
start3 = pos
bits[pos] = 80
pos += 1
break
pos += 1
# P4
while pos < cnt - 16*1024:
if A[pos] < avg and A[pos+1] > avg:
start4 = pos
bits[pos] = 70
pos += 1
break
pos += 1
sig_diff = start4 - start1
if 20 < sig_diff < 25:
bits[msg_start] = 500
bit_len = int((start4 - start1) / 4.5)
# print(pos, start1, start4, ' - ', bit_len)
# start = start1 + 8*bit_len
parse_message(A, msg_start, bit_len)
pos += 450
# For debugging: check signal start
# plt.plot(A)
# plt.plot(bits)
# plt.show()
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