The Python ADS-B/Mode-S Decoder

If you find this project useful for your research, please cite our work (bibtex format):

@article{sun2019pymodes,
    author={J. {Sun} and H. {V\^u} and J. {Ellerbroek} and J. M. {Hoekstra}},
    journal={IEEE Transactions on Intelligent Transportation Systems},
    title={pyModeS: Decoding Mode-S Surveillance Data for Open Air Transportation Research},
    year={2019},
    doi={10.1109/TITS.2019.2914770},
    ISSN={1524-9050},
}

Introduction

PyModeS is a Python library designed to decode Mode-S (including ADS-B) message. Message with following Downlink Formats (DF) are supported:

DF17 / DF18: Automatic Dependent Surveillance - Broadcast (ADS-B)

TC=1-4 / BDS 0,8: Aircraft identification and category
TC=5-8 / BDS 0,6: Surface position
TC=9-18 / BDS 0,5: Airborne position
TC=19 / BDS 0,9: Airborne velocity
TC=28 / BDS 6,1: Airborne status [to be implemented]
TC=29 / BDS 6,2: Target state and status information [to be implemented]
TC=31 / BDS 6,5: Aircraft operational status [to be implemented]

DF20 / DF21: Mode-S Comm-B replies

BDS 1,0: Data link capability report
BDS 1,7: Common usage GICB capability report
BDS 2,0: Aircraft identification
BDS 3,0: ACAS active resolution advisory
BDS 4,0: Selected vertical intention
BDS 4,4: Meteorological routine air report (experimental)
BDS 4,5: Meteorological hazard report (experimental)
BDS 5,0: Track and turn report
BDS 6,0: Heading and speed report

DF4 / DF20: Altitude code

DF5 / DF21: Identity code (squawk code)

Resources

Checkout and contribute to this open-source project at: https://github.com/junzis/pyModeS

Detailed manual on Mode-S decoding is published at: https://mode-s.org/decode.

API documentation of pyModeS is at: http://pymodes.readthedocs.io

Install

To install latest version from the GitHub:

pip install git+https://github.com/junzis/pyModeS

To install the stable version (2.0) from pip:

pip install pyModeS

Live view traffic (modeslive)

Supports Mode-S Beast and AVR raw stream

modeslive --server [server_address] --port [tcp_port] --rawtype [beast,avr,skysense] --latlon [lat] [lon]  --dumpto [folder]

Arguments:
  -h, --help           show this help message and exit
  --server SERVER      server address or IP
  --port PORT          raw data port
  --rawtype RAWTYPE    beast, avr or skysense
  --latlon LAT LON     receiver position
  --show-uncertainty   display uncertaint values, default off
  --dumpto             folder to dump decoded output

If you have a RTL-SDR receiver or Mode-S Beast, use modesmixer2 (http://xdeco.org/?page_id=48) to create raw beast TCP stream:

$ modesmixer2 --inSeriel port[:speed[:flow_control]] --outServer beast:[tcp_port]

Example screenshot:

Use the library

import pyModeS as pms

Common functions

pms.df(msg)                 # Downlink Format
pms.icao(msg)               # Infer the ICAO address from the message
pms.crc(msg, encode=False)  # Perform CRC or generate parity bit

pms.hex2bin(str)      # Convert hexadecimal string to binary string
pms.bin2int(str)      # Convert binary string to integer
pms.hex2int(str)      # Convert hexadecimal string to integer
pms.gray2int(str)     # Convert grey code to interger

Core functions for ADS-B decoding

pms.adsb.icao(msg)
pms.adsb.typecode(msg)

# Typecode 1-4
pms.adsb.callsign(msg)

# Typecode 5-8 (surface), 9-18 (airborne, barometric height), and 9-18 (airborne, GNSS height)
pms.adsb.position(msg_even, msg_odd, t_even, t_odd, lat_ref=None, lon_ref=None)
pms.adsb.airborne_position(msg_even, msg_odd, t_even, t_odd)
pms.adsb.surface_position(msg_even, msg_odd, t_even, t_odd, lat_ref, lon_ref)

pms.adsb.position_with_ref(msg, lat_ref, lon_ref)
pms.adsb.airborne_position_with_ref(msg, lat_ref, lon_ref)
pms.adsb.surface_position_with_ref(msg, lat_ref, lon_ref)

pms.adsb.altitude(msg)

# Typecode: 19
pms.adsb.velocity(msg)          # Handles both surface & airborne messages
pms.adsb.speed_heading(msg)     # Handles both surface & airborne messages
pms.adsb.surface_velocity(msg)
pms.adsb.airborne_velocity(msg)

Note: When you have a fix position of the aircraft, it is convenient to use position_with_ref() method to decode with only one position message (either odd or even). This works with both airborne and surface position messages. But the reference position shall be with in 180NM (airborne) or 45NM (surface) of the true position.

Decode altitude replies in DF4 / DF20

pms.common.altcode(msg)   # Downlink format must be 4 or 20

Decode identity replies in DF5 / DF21

pms.common.idcode(msg)   # Downlink format must be 5 or 21

Common Mode-S functions

pms.icao(msg)           # Infer the ICAO address from the message
pms.bds.infer(msg)      # Infer the Modes-S BDS register

# Check if BDS is 5,0 or 6,0, give reference speed, track, altitude (from ADS-B)
pms.bds.is50or60(msg, spd_ref, trk_ref, alt_ref)

# Check each BDS explicitly
pms.bds.bds10.is10(msg)
pms.bds.bds17.is17(msg)
pms.bds.bds20.is20(msg)
pms.bds.bds30.is30(msg)
pms.bds.bds40.is40(msg)
pms.bds.bds44.is44(msg)
pms.bds.bds50.is50(msg)
pms.bds.bds60.is60(msg)

Mode-S Elementary Surveillance (ELS)

pms.commb.ovc10(msg)      # Overlay capability, BDS 1,0
pms.commb.cap17(msg)      # GICB capability, BDS 1,7
pms.commb.cs20(msg)       # Callsign, BDS 2,0

Mode-S Enhanced Surveillance (EHS)

# BDS 4,0
pms.commb.alt40mcp(msg)   # MCP/FCU selected altitude (ft)
pms.commb.alt40fms(msg)   # FMS selected altitude (ft)
pms.commb.p40baro(msg)    # Barometric pressure (mb)

# BDS 5,0
pms.commb.roll50(msg)     # Roll angle (deg)
pms.commb.trk50(msg)      # True track angle (deg)
pms.commb.gs50(msg)       # Ground speed (kt)
pms.commb.rtrk50(msg)     # Track angle rate (deg/sec)
pms.commb.tas50(msg)      # True airspeed (kt)

# BDS 6,0
pms.commb.hdg60(msg)      # Magnetic heading (deg)
pms.commb.ias60(msg)      # Indicated airspeed (kt)
pms.commb.mach60(msg)     # Mach number (-)
pms.commb.vr60baro(msg)   # Barometric altitude rate (ft/min)
pms.commb.vr60ins(msg)    # Inertial vertical speed (ft/min)

Meteorological routine air report (MRAR) [Experimental]

# BDS 4,4
pms.commb.wind44(msg)     # Wind speed (kt) and direction (true) (deg)
pms.commb.temp44(msg)     # Static air temperature (C)
pms.commb.p44(msg)        # Average static pressure (hPa)
pms.commb.hum44(msg)      # Humidity (%)

Meteorological hazard air report (MHR) [Experimental]

# BDS 4,5
pms.commb.turb45(msg)     # Turbulence level (0-3)
pms.commb.ws45(msg)       # Wind shear level (0-3)
pms.commb.mb45(msg)       # Microburst level (0-3)
pms.commb.ic45(msg)       # Icing level (0-3)
pms.commb.wv45(msg)       # Wake vortex level (0-3)
pms.commb.temp45(msg)     # Static air temperature (C)
pms.commb.p45(msg)        # Average static pressure (hPa)
pms.commb.rh45(msg)       # Radio height (ft)

Customize the streaming module

The TCP client module from pyModeS can be re-used to stream and process Mode-S data as your like. You need to re-implement the handle_messages() function from the BaseClient class to write your own logic to handle the messages.

Here is an example:

from pyModeS.extra.tcpclient import BaseClient

# define your custom class by extending the BaseClient
#   - implement your handle_messages() methods
class ADSBClient(BaseClient):
    def __init__(self, host, port, rawtype):
        super(ModesClient, self).__init__(host, port, rawtype)

    def handle_messages(self, messages):
        for msg, ts in messages:
            if len(msg) < 28:           # wrong data length
                continue

            df = pms.df(msg)

            if df != 17:                # not ADSB
                continue

            if '1' in pms.crc(msg):     # CRC fail
                continue

            icao = pms.adsb.icao(msg)
            tc = pms.adsb.typecode(msg)

            # TODO: write you magic code here
            print ts, icao, tc, msg

# run new client, change the host, port, and rawtype if needed
client = ADSBClient(host='127.0.0.1', port=30334, rawtype='beast')
client.run()

Unit test

To perform unit tests. First install tox through pip, Then, run the following commands:

$ tox

DetectedStorm/pyModeS