NMEA 0183
Overview
NMEA 0183 is a protocol commonly used on marine electronics such as GPS devices. NMEA transmits data over a serial, text-based protocol (see NMEA 0183 on Wikipedia for protocol details). NMEA messages consist of a “sentence”, a unit of data containing a message identifier and list of comma-delimited values.
Most consumer-grade GPS devices use NMEA 0183, and TelemetryJet will work directly with most USB GPS modules.
Supported Sentences
TelemetryJet can read the following commonly-used GPS sentences:
- GPGGA: Timestamp, position, and fix data.
- GPGSA: Fix data including precision values.
- GPGSV: Position and signal strength information for active satellites.
- GPRMC: Timestamp, position, speed, and heading.
- GPVTG: Heading and speed data.
Data from the sentences received may overlap, and the system will use the best available data possible.
Data Points
The following data is available from NMEA 0183 devices:
- Status
- Fix Type
- Quality
- dilution
- horizontalDilution
- verticalDilution
- altitude
- latitude
- longitude
- speed
- travelAngle
- trackingSatellites
- visibleSatellites
- locked
- horizontalAccuracy
- verticalAccuracy
- hasEstimate
- gpsTimestamp
Configuration
Data Point Filtering
Depending on the device, there may be a large amount of data available from the GPS, including satellite positions, signal strength, and other metadata, as shown by the list above.
By default, only the most relevant data is saved: position, speed, fix status, and number of satellites. If you would like to change which data points from the list above are saved, individual data points can be enabled/disabled from the device protocol settings.
Data Rate
The rate that the data from a NMEA 0183 device is saved as a data point can be configured in the device protocol settings. The default is 1 second.