Talofa Habr. Masalo o tagata uma na feiloai pe vaʻavaʻai i aiga poʻo uo i luga o se vaalele na faʻaaogaina le auaunaga Flightradar24 e leai se totogi. O se auala faigofie tele lea e siaki ai le tulaga o le vaalele i le taimi moni.
В Na fa'amatalaina le fa'aogaina o sea auaunaga i luga ole laiga. O le a tatou agai i luma ma fuafua po o le a le faʻamatalaga o loʻo lafoina ma maua mai le vaalele i le nofoaga e maua ai ma faʻavasegaina i tatou lava e faʻaaoga ai le Python.
История
E manino lava, e le tuʻuina atu faʻamatalaga vaalele mo tagata faʻaoga e vaʻai i luga o latou telefoni. O le faiga e taʻua o le ADS-B (Automatic dependent surveillance-broadcast), ma e faʻaaogaina e otometi ai ona tuʻuina atu faʻamatalaga e uiga i le vaalele i le nofoaga tutotonu - o lona faʻamatalaga, faʻamaopoopo, faʻatonuga, saoasaoa, maualuga ma isi faʻamatalaga e tuʻuina atu. I le taimi muamua, aʻo leʻi oʻo mai ia faiga, na mafai e le avefeʻau ona vaʻaia se mea i luga o le radar. Sa le toe lava lea ina ua tele naua vaalele.
Faʻapitoa, ADS-B o loʻo i ai se faʻasalalauga i luga o se vaalele e auina atu i lea taimi ma lea taimi faʻamatalaga o faʻamatalaga i se maualuga maualuga o le 1090 MHz (o loʻo i ai isi auala, ae matou te le fiafia tele ia i latou, talu ai o faʻasalalauga e faʻasalalau naʻo iinei). Ioe, i le faaopoopo atu i le transmitter, o loʻo i ai foi se tagata e taliaina i se mea i le malaevaalele, ae mo i matou, i le avea ai ma tagata faʻaoga, o la matou lava tagata e taliaina e manaia.
I le ala, mo le faʻatusatusaga, o le faiga muamua, Airnav Radarbox, na fuafuaina mo tagata faʻaoga masani, na faʻaalia i le 2007, ma e tusa ma le $ 900; o le saofaga i auaunaga tau fesoʻotaʻiga e tau ai le isi $ 250 i le tausaga.
Fa'amatalaga o na tagata Rusia muamua e mafai ona faitau i luga o le fono . O lea la ua maua lautele RTL-SDR receivers, o se masini faapena e mafai ona faʻapotopotoina mo le $30; sili atu e uiga i lenei mea i totonu. . Sei o tatou agai i luma i le protocol lava ia - sei o tatou vaai pe faapefea ona aoga.
Mauaina o faailoilo
Muamua, e manaʻomia ona faʻamaumau le faailo. O le faʻailoga atoa e naʻo le 120 microseconds le umi, ina ia faʻamalieina le faʻamavaeina o ona vaega, e manaʻomia se SDR receiver ma se faʻataʻitaʻiga masani o le itiiti ifo i le 5 MHz.
A maeʻa ona puʻeina, matou te mauaina se faila WAV ma se fua faatatau o le 5000000 faʻataʻitaʻiga / sec; 30 sekone o sea faʻamaumauga "mamafa" e uiga i le 500MB. O le fa'alogo i ai ma se tagata fa'asalalau, ioe, e leai se aoga - o le faila e leai se leo, ae o se fa'ailoga fa'akomepiuta sa'o - o le auala tonu lea e galue ai Software Defined Radio.
Matou te tatalaina ma faʻagasolo le faila e faʻaaoga ai le Python. O i latou e manana'o e fa'ata'ita'i i latou lava e mafai ona la'uina mai se fa'ata'ita'iga fa'amaumauga .
Se'i tatou la'u mai le faila ma va'ai po'o a mea o lo'o i totonu.
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()
I'uga: matou te va'aia ni "pu'i" fa'asaga i le pisa i tua.
O "pulse" taʻitasi o se faʻailoga, o le fausaga o loʻo faʻaalia manino pe afai e te faʻateleina le iuga i luga o le kalafi.
E pei ona e vaʻaia, o le ata e fetaui lelei ma mea o loʻo tuʻuina atu i le faʻamatalaga i luga. E mafai ona e amata fa'agasolo fa'amaumauga.
Filifiliga
Muamua, e manaʻomia ona e maua sina tafe. O le faʻailoga lava ia e faʻaogaina e faʻaoga ai Manchester encoding:
Mai le eseesega tulaga i nibbles e faigofie ona maua moni "0" ma le "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"
O le fausaga o le faailo lava ia e faapea:
Se'i o tatou va'ai atili i fanua.
DF (Downlink Format, 5 bits) - fuafua le ituaiga o feʻau. E tele ituaiga:
()
Matou te fiafia i le ituaiga DF17, aua ... O le mea lea o loʻo i ai faʻasalalauga o le vaalele.
ICAO (24 bits) - tulafono fa'avaomalo tulaga ese o le va'alele. E mafai ona e siaki le vaalele i lona code (Ae paga lea, ua taofia e le tusitala le faʻafouina o le database, ae o loʻo talafeagai pea). Mo se faʻataʻitaʻiga, mo le code 3c5ee2 matou te maua faʻamatalaga nei:
Fa'atonu: i O le faʻamatalaga o le ICAO code o loʻo tuʻuina atu i nisi auiliiliga; Ou te fautuaina i latou e fiafia e faitau i ai.
faʻamatalaga (56 poʻo 112 bits) - o faʻamatalaga moni o le a matou faʻavasegaina. O le 5 bits muamua o faʻamaumauga o le fanua Ituaiga Code, o loʻo i ai le subtype o faʻamaumauga o loʻo teuina (aua le fenumiai ma le DF). E tele naua ituaiga nei:
()
Se'i o tatou va'ai i nai fa'ata'ita'iga o afifi.
Fa'ailoga va'alele
Faataitaiga ile faiga binary:
00100 011 000101 010111 000111 110111 110001 111000
Fa'amaumauga:
+------+------+------+------+------+------+------+------+------+------+
| TC,5 | EC,3 | C1,6 | C2,6 | C3,6 | C4,6 | C5,6 | C6,6 | C7,6 | C8,6 |
+------+------+------+------+------+------+------+------+------+------+
TC = 00100b = 4, o uiga ta'itasi C1-C8 o lo'o iai fa'ailoga e fetaui ma fa'ailoga i le laina:
#ABCDEFGHIJKLMNOPQRSTUVWXYZ######_################0123456789######
E ala i le fa'avasegaina o le manoa, e faigofie ona maua le va'alele code: 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('#', ''))
Tulaga i luga ole ea
Afai e faigofie le igoa, ona sili atu lea ona lavelave faamaopoopo. O loʻo tuʻuina atu i latou i foliga o 2, tutusa ma faʻailoga faʻapitoa. Fa'ailoga fanua TC = 01011b = 11.
Fa'ata'ita'iga o taga e tutusa ma fa'ailoga e ese:
01011 000 000101110110 00 10111000111001000 10000110101111001
01011 000 000110010000 01 10010011110000110 10000011110001000
O le faʻatulagaina o faʻamaopoopo lava ia e tupu e tusa ai ma se faiga faʻapitoa:
()
E le o aʻu o se tagata tomai faapitoa i le GIS, o lea ou te le iloa po o fea e sau ai. O ai na te iloa, tusi i faʻamatalaga.
O le maualuga e manatu e sili atu ona faigofie - e faʻatatau i le vaega faʻapitoa, e mafai ona faʻatusalia a le o le tele o le 25 pe 100 futu.
Savili Va'alele
Paketi ma le TC=19. O le mea manaia iinei o le saoasaoa e mafai ona saʻo, faʻatatau i le eleele (Ground Speed), poʻo le ea, fuaina e se vaʻalele (Airspeed). Le tele o vaega eseese o loʻo tuʻuina atu foi:
()
iʻuga
E pei ona mafai ona e vaʻaia, o le tekinolosi ADS-B ua avea ma se faʻataʻitaʻiga manaia, pe a aoga se faʻataʻitaʻiga e le gata i polofesa, ae faʻapea foʻi i tagata masani. Ae o le mea moni, o se matafaioi taua i lenei mea na faia e le tekinolosi taugofie o numera SDR receivers, lea e mafai ai e le masini ona maua moni faailoilo i luga o le gigahertz "mo pene."
I le tulaga lava ia, ioe, e tele atu isi mea. O i latou e fiafia e mafai ona matamata i le PDF i luga o le itulau pe asiasi i le ua uma ona taʻua i luga .
E foliga mai o mea uma o loʻo i luga o le a aoga i le toʻatele, ae o le manatu lautele o le auala e galue ai, ou te faʻamoemoe, e tumau.
I le auala, ua uma ona i ai se decoder saunia i le Python, e mafai ona e suʻesuʻeina . Ma e mafai e tagata e ona SDR receivers ona faʻapipiʻi ma faʻalauiloa se faʻasalalauga ADS-B ua saunia , lea na talanoaina atili auiliili i .
O le code source o le parser o loʻo faʻamatalaina i le tusiga o loʻo tuʻuina atu i lalo ifo o le tipi. O se faʻataʻitaʻiga faʻataʻitaʻiga lea e le faʻafoliga o se gaosiga, ae o nisi mea o loʻo galue i totonu, ma e mafai ona faʻaaogaina e faʻasalalau le faila o loʻo faʻamauina i luga.
Fa'ailoga puna (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()
Ou te faʻamoemoe sa i ai se tasi na fiafia, faʻafetai mo lou faʻalogo.
puna: www.habr.com