NMEA-0183 Decoder/Encoder

Decoder/encoder for NMEA-0183 message types.

Installing

npm install -S @gnss/nmea

Basic Usage

Decoding

let buffer: string = ...; // String containing NMEA sentence
let message: NmeaMessage = NmeaTransport.decode(buffer);

Encoding

let message = ...; // Message to be encoded
let buffer: string = NmeaTransport.encode(message);

Creating

Messages can be manually constructed using NmeaMessage???.construct({}), which requires all message properties to be provided.

NmeaMessageGga.construct({
    talker: NmeaTalker.NAV_SYSTEM_GNSS,
    time: new Date(0, 0, 0, 1, 2, 3, 0),
    latitude: 66.66,
    longitude: 33.33,
    quality: NmeaFixQuality.SIMULATOR,
    numberSatellites: 10,
    hdop: 2.5,
    altitude: 180.00,
    geoidalSeparation: 90.00,
    differentialAge: 5,
    differentialStationId: 'differentialStationId',
})

Streams

Transform streams to convert from NmeaMessages to sentence strings and vice-versa.

let input: stream.Readable = ...;
let output: stream.Writable = ...;
input                                      // Stream of sentence strings
    .pipe(new NmeaDecodeTransformStream()) // Stream of NmeaMessage objects
    .pipe(new NmeaEncodeTransformStream()) // Stream of (identical) sentence strings
    .pipe(output);

NmeaDecodeTransformStream can optionally synchronize with the data stream e.g. if it starts receiving data from the middle of a message.

Messages Supported

• DTM (NmeaMessageDtm)
• GBS (NmeaMessageGbs)
• GGA (NmeaMessageGga)
• GLL (NmeaMessageGll)
• GNS (NmeaMessageGns)
• GRS (NmeaMessageGrs)
• GSA (NmeaMessageGsa)
• GST (NmeaMessageGst)
• GSV (NmeaMessageGsv)
• RMC (NmeaMessageRmc)
• THS (NmeaMessageThs)
• TXT (NmeaMessageTxt)
• VHW (NmeaMessageVhw)
• VLW (NmeaMessageVlw)
• VPW (NmeaMessageVpw)
• VTG (NmeaMessageVtg)
• ZDA (NmeaMessageZda)

Testing

npm test

License

GPLv3

Contributions

Contributions of new sentence types, bug fixes and general improvements via pull requests are welcome. Please ensure that code style matches that of the existing files.