taquitos / gdl90

GDL 90 decode/encode tools and libraries

GDL 90 Decoder and Encoder

This package is a set of tools and libraries for decoding and encoding the GDL 90 protocol used for ADS-B in transmissions. The focus of this package is on a client application within an aircraft that is receiving a data stream from an ADS-B hardware device. Any sending tools are meant to simulate the hardware device for a listening client application.

Unless otherwise stated in the included files, the files within this package are subject to the following copyright and license.

Copyright (c) 2016 Eric Dey

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Package Overview

The package requires Python 2.6 or 2.7 and makes use of the Python Standard Library for all functions except where noted. The primary tool components are:

• gdl90_receiver.py -- receives a live or recorded data stream from ADS-B hardware
• gld90_recorder.py -- records the raw data stream from ADS-B hardware to file
• gld90_sender.py -- sends a previously recorded data stream to network

The gdl90 subdirectory contains the libraries for decoding and encoding the GDL 90 and UAT messages.

Receiver

The receiver can be used decode a live data stream or process a recorded GLD 90 file. The output is a line-by-line decoding of the individual message types, including the optional UAT messages, or a compact text record format that allows for automated processing.

$ ./gdl90_receiver.py --help
Usage: gdl90_receiver.py {requiredOptions} [otherOptions]

GDL-90 Receiver is a data receiver and decoder.

Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  -v, --verbose         Verbose reporting on STDERR

  Optional:
    -p NUM, --port=NUM  receive port (default=43211)
    -s BYTES, --maxsize=BYTES
                        maximum packet size (default=9000)
    -r PACKETS, --reportcount=PACKETS
                        report after receiving this many packets (default=100)
    -i FILE, --inputfile=FILE
                        read from input file instead of network
    --date=YYYY-MM-DD   UTC starting date for data (default=now)
    --plotflight        output plotflight format
    --uat               output UAT messages

The decoding library makes use of a non-standard MSG101 from the SkyRadar hardware for time-of-day (hh:mm) since the MSG00 timestamp is not usable as defined in the GDL 90 protocol. Since seconds information is not available when using the SkyRadar hardware, the decoding library self-corrects its internal estimation of the number of seconds past the minute as messages are received.

Example usage:

$ ./gdl90_receiver.py -i skyradar.20121028.001 --plotflight > ../KML/PlotFlight/skyradar.track.20121028.001.txt

Recorder

The recorder captures the raw data stream from an ADS-B device and saves it to a file. It is designed to be run within a device like the RaspberryPi attached to a wifi network within an aircraft. The raw files are later downloaded and processed by the gdl90_receiver.py program.

The recorder has a dependency on the netifaces package for Python. This can be installed on your target system with the command:

sudo pip install netifaces

When running the recorder in a head-less device like the RPi, this should be run as root with the ability to automatically start and restart. An /etc/inittab entry such as this accomplishes these needs:

#Run GDL90 recorder
fdr1:23:respawn:/usr/bin/python /root/gdl90_recorder.py --slowexit

The --slowexit option should be used when running from inittab in order to prevent init from disabling respawns at boot time when the wifi network is still initializing. Until a valid network interface exists, the recorder will exit and needs to be restarted.

$ ./gdl90_recorder.py --help
Usage: gdl90_recorder.py {requiredOptions} [otherOptions]

GDL-90 Recorder is a data receiver.

Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  -v, --verbose         Verbose reporting on STDERR
  --slowexit            Delay error exit for 15 seconds

  Optional:
    --interface=name    receive interface name (default=)
    -p NUM, --port=NUM  receive port (default=43211)
    -s BYTES, --maxsize=BYTES
                        maximum packet size (default=1500)
    --dataflush=SECS    seconds between data file flush (default=10)
    --logprefix=PATH    path prefix for log file names
                        (default=/root/skyradar)
    --rebroadcast=name  rebroadcast interface (default=off)

Sender

The sender is useful for replaying a previously recorded data stream from an ADS-B hardware device. This can be used for testing an application or the decoder library.

$ ./gdl90_sender.py --help
Usage: gdl90_sender.py {requiredOptions} [otherOptions]

GDL-90 Sender transmits data to the network.

Options:
  --version             show program's version number and exit
  -h, --help            show this help message and exit
  -v, --verbose         Verbose reporting on STDERR
  -f FILE, --file=FILE  input file (default=STDIN)

  Optional:
    -d IP, --dest=IP    destination IP (default=255.255.255.255)
    -p NUM, --port=NUM  destination port (default=43211)
    -s BYTES, --size=BYTES
                        packet size (default=50)
    --delay=MSEC        time between packets (default=10)