NJORD

NJORD is a Python application designed to augment a GNSS data stream based on known WiFi AP (Access Point) locations. This application is intended for use in a buoy setup to improve GNSS accuracy using WiFi APs. Initial GNSS information is obtained from the AirlinkOS API.

Features

• Updates GNSS state based on known WiFi AP locations.
• Falls back to using the AirlinkOS API for GNSS state if no known APs are available.
• Supports configuration updates from a local file or a remote URL.
• Provides options to send GNSS data via UDP, TCP, or to standard output.

Installation

Ensure you have Python 3.x installed on your system. You can install the required dependencies using pip:

pip install -r requirements.txt

Usage

You can run the NJORD application using the command line. Below are the available options:

usage: njord.py [-h] [-a AOSURL] [-c CONFIG] [-C CONFIG_URL] [-g] [-U UDPPORT]
                [-s] [-t TCPPORT] [-T TCPHOST] [-u USERNAME] [-p PASSWORD]
                [-v] [-B BEACON] [-M {taip_pv,nmea_rmc,all}] [-i UPDATE]
                [-m MSG_TYPE PROTOCOL PORT HOST]
                [-z MSG_TYPE PROTOCOL PORT HOST ALIAS] [-b MSG_TYPE PORT]
                [-Z MSG_TYPE PORT ALIAS] [-n NUM_WIFI_SCAN]
                [-W WIFI_SCAN_DELAY] [-d HDOP_EXCELLENT_THRESHOLD]
                [-D HDOP_POOR_THRESHOLD]

NJORD - A buoy to augment a GNSS data stream based on known Wifi AP locations.

options:
  -h, --help            show this help message and exit
  -a AOSURL, --aosurl AOSURL
                        Base URL for AOS API, defaults to
                        "https://192.168.1.1", if a file path is provided,
                        tries to read the file as a proxy API.
  -c CONFIG, --config CONFIG
                        File path for local config file.
  -C CONFIG_URL, --config_url CONFIG_URL
                        URL to acquire net config files.
  -g, --gateway         Sets the AOS API URL to the network\'s gateway.
                        Overrides --aosurl.
  -U UDPPORT, --udpport UDPPORT
                        UDP port to send GNSS broadcast messages
  -s, --stdout          Prints TAIP messages to Standard Output
  -t TCPPORT, --tcpport TCPPORT
                        TCP Port to send GNSS messages.
  -T TCPHOST, --tcphost TCPHOST
                        TCP Server to send messages.
  -u USERNAME, --username USERNAME
                        Username for AOS authentication. - overrides config
                        file
  -p PASSWORD, --password PASSWORD
                        Password for AOS authentication. - overrides config
                        file
  -v, --verbose         Prints messages to standard output.
  -B BEACON, --beacon BEACON
                        Sets the beacon interval in seconds
  -M {taip_pv,nmea_rmc,all}, --messagetype {taip_pv,nmea_rmc,all}
                        Specify the message type (taip_pv, nmea_rmc, or all).
                        Default is "taip_rmc".
  -i UPDATE, --update UPDATE
                        Sets the config update interval in seconds.
  -m MSG_TYPE PROTOCOL PORT HOST, --message MSG_TYPE PROTOCOL PORT HOST
                        Message parameters: MSG_TYPE (TAIP_PV/NMEA_RMC),
                        PROTOCOL (TCP/UDP), PORT (int), HOST (str)
  -z MSG_TYPE PROTOCOL PORT HOST ALIAS, --message-alias-taip MSG_TYPE PROTOCOL PORT HOST ALIAS
                        Message parameters: MSG_TYPE (TAIP_PV/NMEA_RMC),
                        PROTOCOL (TCP/UDP), PORT (int), HOST (str), TAIP ALIAS
                        (fixed value or +N/-N)
  -b MSG_TYPE PORT, --broadcast-message MSG_TYPE PORT
                        Message parameters: MSG_TYPE (TAIP_PV/NMEA_RMC), PORT
                        (int)
  -Z MSG_TYPE PORT ALIAS, --broadcast-message-alias-taip MSG_TYPE PORT ALIAS
                        Message parameters: MSG_TYPE (TAIP_PV/NMEA_RMC), PORT
                        (int), TAIP ALIAS (fixed value or +N/-N)
  -n NUM_WIFI_SCAN, --num-wifi-scan NUM_WIFI_SCAN
                        Number of times to scan for Wifi APs per beacon
                        interval (int) Defaults is 1.
  -W WIFI_SCAN_DELAY, --wifi-scan-delay WIFI_SCAN_DELAY
                        Delay between subsaquint Wifi scans in seconds.
                        Default is 1.
  -d HDOP_EXCELLENT_THRESHOLD, --hdop-excellent-threshold HDOP_EXCELLENT_THRESHOLD
                        When GNSS data is reported to be less than this value
                        (float), Wifi scan is not performed and GNSS data is
                        reported.
  -D HDOP_POOR_THRESHOLD, --hdop-poor-threshold HDOP_POOR_THRESHOLD
                        When GNSS data has a HDOP greather than this value,
                        the GNSS data is ignored as invalid.

Example

To run NJORD with a local configuration file and send GNSS data to a TCP server:

python3 njord.py -c /path/to/config.json -T your.tcphost.com -t 9011

Configuration

The configuration file should be in JSON format and include the known access points and API credentials. Below is an example of a configuration file:

{
    "KnownAps": [
        {
            "Ssid": "example_ssid",
            "Bssid": "00:11:22:33:44:55",
            "Latitude": 40.7128,
            "Longitude": -74.0060
        }
    ],
    "LastUpdated": "2024-05-28T00:00:00",
    "ApiUser": {
        "Username": "your_username",
        "Password": "your_password"
    }
}

License

NJORD is licensed under the MIT License. See the LICENSE file for more details.

Author

• Joe Porcelli - Initial work - www.kt3i.com

Contributing

Contributions are welcome! Please feel free to submit a pull request or open an issue.

Acknowledgements

• Special thanks to the developers of the requests and argparse libraries for making network requests and command-line argument parsing easier.

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