The Python Mode-S Decoder (2.0-dev)

Python library for Mode-S message decoding. Support Downlink Formats (DF) are:

Automatic Dependent Surveillance - Broadcast (ADS-B) (DF 17/18)

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]

Mode-S Comm-B replies (DF 20 / 21)

BDS 1,0: Data link capability report
BDS 1,7: Common usage GICB capability report
BDS 2,0: Aircraft identification
BDS 2,1: Aircraft and airline registration markings
BDS 3,0: ACAS active resolution advisory
BDS 4,0: Selected vertical intention
BDS 4,4: Meteorological routine air report
BDS 5,0: Track and turn report
BDS 5,3: Air-referenced state vector
BDS 6,0: Heading and speed report

DF4 / DF20: Altitude code

DF4 / DF21: Identity code (squawk)

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

New features in v2.0

New structure of the libraries
ADS-B and Comm-B data streaming
Active aircraft viewing (terminal curses)
Improved BDS identification
Optimizing decoding speed

Source code

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

API documentation at: http://pymodes.readthedocs.io [To be updated]

Install

To install latest development version (dev-2.0) from the GitHub:

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

Live view traffic (pmslive)

Supports Mode-S Beast and AVR raw stream

pmslive --server [server_address] --port [tcp_port] --rawtype [beast_or_avr] --latlon [lat] [lon]

Arguments:
  -h, --help         show this help message and exit
  --server SERVER    server address or IP
  --port PORT        raw data port
  --rawtype RAWTYPE  beast or avr
  --latlon LAT LON   receiver position

Example screen shot:

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 code

# check if BDS is 5,0 or 6,0, give reference spd, trk, alt (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)

# for BDS code 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)

# for BDS code 5,0
pms.commb.roll50(msg)     # roll angle (deg)
pms.commb.trk50(msg)      # 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)

# for BDS code 6,0
pms.commb.hdg60(msg)      # 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]

# for BDS code 4,4
pms.commb.wind44(msg, rev=False)  # wind speed (kt) and heading (deg)
pms.commb.temp44(msg, rev=False)  # temperature (C)
pms.commb.p44(msg, rev=False)     # pressure (hPa)
pms.commb.hum44(msg, rev=False)   # humidity (%)

Developement

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

$ tox

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