aeroevan / pyModeS

A Python Mode-S Decoder for ADS-B (DF17) and EHS (DF20/21)

A Python Mode-S Decoder

Python library for Mode-S message decoding. Two seprate methods are develop to decode the following messages:

• Automatic Dependent Surveillance - Broadcast (ADS-B) (DF17)
  • aircraft infomation that cotains: icao address, position, altitude, velocity (ground speed), and callsign, etc.
• Mode-S Enhanced Surveillance (EHS) (DF20 and DF21)
  • additional information in response to SSR interogation, such as: true airspeed, indicated airspeed, mach number, track angle, heading, and roll angle, etc.

A detailed manuel on Mode-S decoding is published by the author, at: http://adsb-decode-guide.readthedocs.org

Source code

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

Install

Checkout source code, or install using pip:

pip install pyModeS

Usage

import pyModeS as pms

Common function for Mode-S message:

pms.df(msg)                 # Downlink Format
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

Core functions for ADS-B decoding:

pms.adsb.icao(msg)
pms.adsb.callsign(msg)
pms.adsb.position(msg_odd, msg_even, t_odd, t_even)
pms.adsb.altitude(msg)
pms.adsb.velocity(msg)
pms.adsb.speed_heading(msg)

Core functions for EHS decoding:

pms.ehs.icao(msg)       # icao address
pms.ehs.BDS(msg)        # Comm-B Data Selector Version

# for BDS version 2,0
pms.ehs.callsign(msg)   # Aircraft callsign

# for BDS version 4,0
pms.ehs.alt_mcp(msg)    # MCP/FCU selected altitude (ft)
pms.ehs.alt_fms(msg)    # FMS selected altitude (ft)
pms.ehs.alt_pbaro(msg)  # Barometric pressure (mb)

# for BDS version 5,0
pms.ehs.roll(msg)       # roll angle (deg)
pms.ehs.track(msg)      # track angle (deg)
pms.ehs.gs(msg)         # ground speed (kt)
pms.ehs.rtrack(msg)     # track angle rate (deg/sec)
pms.ehs.tas(msg)        # true airspeed (kt)

# for BDS version 6,0
pms.ehs.heading(msg)    # heading (deg)
pms.ehs.ias(msg)        # indicated airspeed (kt)
pms.ehs.mach(msg)       # MACH number
pms.ehs.baro_vr(msg)    # barometric altitude rate (ft/min)
pms.ehs.ins_vr(msg)     # inertial vertical speed (ft/min)

Some helper functions:

pms.df(msg)             # downlink format of a Mode-S message
pms.hex2bin(msg)        # convert hexadecimal string to binary string
pms.hex2int(msg)        # convert hexadecimal string to integer
pms.bin2int(msg)        # convert binary string to integer