Ndewo Habr. Eleghị anya, onye ọ bụla hụtụrụla ma ọ bụ hụ na ndị ikwu ma ọ bụ ndị enyi nọ n'ụgbọelu ejirila ọrụ Flightradar24 n'efu. Nke a bụ ụzọ dị mma iji soro ọnọdụ ụgbọ elu ahụ ozugbo.
В A kọwara ụkpụrụ ọrụ nke ọrụ ịntanetị dị otú ahụ. Ugbu a, anyị ga-aga n'ihu ma chọpụta ihe data a na-eziga na natara site na ụgbọ elu gaa na ọdụ nnata ma depụta ya n'onwe anyị site na iji Python.
История
N'ụzọ doro anya, a naghị ebufe data ụgbọ elu maka ndị ọrụ ịhụ na ekwentị ha. A na-akpọ usoro a ADS-B (Automatic dabere onyunyo-mgbasa ozi), na-eji na-akpaghị aka na-ebufe ozi gbasara ụgbọ elu na ebe njikwa - njirimara ya, nhazi, ntụziaka, ọsọ, elu na data ndị ọzọ. Na mbụ, tupu ọbịbịa nke usoro ndị dị otú ahụ, onye na-ezipụ ozi nwere ike ịhụ naanị otu isi na radar. Nke a ezughịkwa mgbe enwere ọtụtụ ụgbọ elu.
Teknụzụ, ADS-B nwere onye na-ebugharị na ụgbọ elu nke na-eziga ngwugwu ozi kwa oge n'ogo dị elu nke 1090 MHz (enwere ụdịdị ndị ọzọ, mana anyị enweghị mmasị na ha, ebe ọ bụ na a na-ebunye nhazi naanị ebe a). N'ezie, na mgbakwunye na onye na-ebugharị, e nwekwara onye na-anata ebe n'ọdụ ụgbọ elu, ma maka anyị, dị ka ndị ọrụ, onye na-anata onwe anyị na-adọrọ mmasị.
Site n'ụzọ, maka ntụnyere, usoro mbụ dị otú ahụ, Airnav Radarbox, nke e mere maka ndị ọrụ nkịtị, pụtara na 2007, na-efu ihe dị ka $900; ndenye aha na ọrụ netwọk na-efu $ 250 ọzọ kwa afọ.
Enwere ike ịgụ nyocha nke ndị nwe Russia mbụ na forum . Ugbu a ndị na-anata RTL-SDR adịla ebe niile, enwere ike ikpokọta ngwaọrụ yiri ya maka $30; ihe gbasara nke a dị na . Ka anyị gaa n'ihu na protocol n'onwe ya - ka anyị hụ ka o si arụ ọrụ.
Ịnata akara
Nke mbụ, ọ dị mkpa ka edekọ mgbaàmà ahụ. Mgbama ahụ dum nwere ogologo oge nke naanị 120 microseconds, yabụ iji kesaa ihe ndị mejupụtara ya nke ọma, onye na-anata SDR nwere oge nlele nke opekata mpe 5 MHz bụ ihe na-achọsi ike.
Mgbe ndekọ, anyị na-enweta a WAV faịlụ na a sample ọnụego nke 5000000 samples / sk; 30 sekọnd nke ndekọ dị otú ahụ "na-atụ" banyere 500MB. Iji ihe ọkpụkpọ mgbasa ozi na-ege ya ntị, n'ezie, abaghị uru - faịlụ ahụ enweghị ụda, mana akara redio digitized ozugbo - otu a ka Software Defined Radio si arụ ọrụ.
Anyị ga-emepe ma hazie faịlụ ahụ site na iji Python. Ndị chọrọ ịnwale n'onwe ha nwere ike budata ndekọ ndekọ ihe atụ .
Ka anyị budata faịlụ ahụ wee hụ ihe dị n'ime.
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()
Nsonaazụ: anyị na-ahụ "pulses" doro anya megide mkpọtụ ndabere.
Onye ọ bụla "pulse" bụ ihe mgbaàmà, usoro nke a na-ahụ anya nke ọma ma ọ bụrụ na ị na-abawanye mkpebi na eserese ahụ.
Dị ka ị na-ahụ, foto a dabara nke ọma na ihe e nyere na nkọwa dị n'elu. Ị nwere ike ịmalite nhazi data.
Ịmepụta koodu
Nke mbụ, ịkwesịrị ịnweta ntakịrị iyi. A na-etinye akara ngosi ahụ n'onwe ya site na iji koodu Manchester:
Site na ọkwa dị iche na nibbles ọ dị mfe ịnweta ezigbo "0" na "1".
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"
Ọdịdị nke mgbaàmà n'onwe ya bụ nke a:
Ka anyị leba anya n'ubi ahụ n'ụzọ zuru ezu.
DF (Downlink Format, 5 bits) - na-ekpebi ụdị ozi. Enwere ọtụtụ ụdị:
()
Anyị nwere mmasị na ụdị DF17, n'ihi na ... Ọ bụ nke a nwere nhazi nke ụgbọ elu.
ICAO (24 bits) - koodu pụrụ iche nke mba ụwa. Ị nwere ike ịlele ụgbọ elu site na koodu ya (n'ụzọ dị mwute, onye edemede akwụsịla imelite nchekwa data, ma ọ ka dị mkpa). Dịka ọmụmaatụ, maka koodu 3c5ee2 anyị nwere ozi ndị a:
Dezie: in Enyere nkọwa nke koodu ICAO n'ụzọ zuru ezu; Ana m akwado ka ndị nwere mmasị gụọ ya.
data (56 ma ọ bụ 112 ibe n'ibe) - ezigbo data anyị ga-achọpụta. Nke mbụ 5 bit nke data bụ ubi Codedị Koodu, nwere subtype nke data a na-echekwa (ka DF ghara mgbagwoju anya). Enwere ole na ole n'ime ụdị ndị a:
()
Ka anyị lee ihe atụ ole na ole nke ngwugwu.
njirimara ụgbọ elu
Ọmụmaatụ n'ụdị ọnụọgụ abụọ:
00100 011 000101 010111 000111 110111 110001 111000
Ebe data:
+------+------+------+------+------+------+------+------+------+------+
| TC,5 | EC,3 | C1,6 | C2,6 | C3,6 | C4,6 | C5,6 | C6,6 | C7,6 | C8,6 |
+------+------+------+------+------+------+------+------+------+------+
TC = 00100b = 4, agwa ọ bụla C1-C8 nwere koodu kwekọrọ na indices na ahịrị:
#ABCDEFGHIJKLMNOPQRSTUVWXYZ#######################0123456789#####
Site na imezi eriri ahụ, ọ dị mfe ịnweta koodu ụgbọ elu: 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('#', ''))
Ọnọdụ ikuku
Ọ bụrụ na aha ahụ dị mfe, mgbe ahụ, nhazi ndị ọzọ dị mgbagwoju anya. A na-ebunye ha n'ụdị nke 2, ọbụna na okpokolo agba na-adịghị mma. Koodu mpaghara TC = 01011b = 11.
Ọmụmaatụ nke ngwungwu ọbụna na ndị na-adịghị mma:
01011 000 000101110110 00 10111000111001000 10000110101111001
01011 000 000110010000 01 10010011110000110 10000011110001000
Mgbakọ nke nhazi n'onwe ya na-eme dịka usoro aghụghọ siri dị:
()
Abụghị m ọkachamara GIS, yabụ na amaghị m ebe o si abịa. Onye maara, dee na nkọwa.
A na-ewere ịdị elu dị mfe - dabere na ntakịrị ntakịrị, enwere ike ịnọchite anya ya dị ka otutu nke 25 ma ọ bụ 100 ụkwụ.
Ọsọ ikuku
Ngwugwu ya na TC=19. Ihe na-adọrọ mmasị ebe a bụ na ọsọ nwere ike ịbụ nke ziri ezi, n'ihe gbasara ala (Ground Speed), ma ọ bụ ikuku, nke ihe mmetụta ụgbọ elu (Airspeed) tụrụ atụ. A na-ekesakwa ọtụtụ mpaghara dị iche iche:
()
nkwubi
Dị ka ị pụrụ ịhụ, ADS-B technology aghọwo ihe na-akpali symbiosis, mgbe ọkọlọtọ bara uru ọ bụghị nanị na ndị ọkachamara, kamakwa ndị ọrụ nkịtị. Mana n'ezie, ọrụ dị mkpa na nke a bụ teknụzụ dị ọnụ ala nke ndị na-anata SDR dijitalụ, nke na-enye ohere ka ngwaọrụ ahụ nweta akara n'ụzọ nkịtị na ugboro ugboro karịa gigahertz “maka pennies.”
Na ọkọlọtọ n'onwe ya, n'ezie, e nwere ọtụtụ ihe ndị ọzọ. Ndị nwere mmasị nwere ike ịlele PDF na ibe ma ọ bụ gaa na nke a kpọtụrụ aha n'elu .
O yighị ka ihe niile a dị n'elu ga-aba uru nye ọtụtụ ndị, ma ọ dịkarịa ala, echiche izugbe nke otú o si arụ ọrụ, m na-atụ anya, na-anọgide.
Site n'ụzọ, ihe ndozi emebere na Python adịlarị, ị nwere ike ịmụ ya . Ndị nwe ndị na-anata SDR nwere ike ịgbakọta ma malite ihe ndozi ADS-B emebere , A tụlere nke a n'ụzọ zuru ezu na .
Enyere koodu isi mmalite nke parser nke akọwara n'isiokwu a n'okpuru ịkpụ. Nke a bụ ihe atụ nnwale nke na-adịghị eme ka ọ bụ mmepụta, mana ụfọdụ ihe na-arụ ọrụ na ya, enwere ike iji ya mee ka faịlụ ahụ dekọọ n'elu.
Koodu isi mmalite (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()
Enwere m olileanya na mmadụ nwere mmasị, daalụ maka nlebara anya gị.
isi: www.habr.com