Nmea Gps

📡 NMEA GPS Integration

🛰️ Overview

MAPS Messaging supports parsing, publishing, and transforming GPS data received in NMEA (National Marine Electronics Association) format. The server can act as a location source and convert raw NMEA sentences into structured JSON.

Configuration for this module is handled via the nmea.yaml file.

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⚙️ Configuration Reference

nmea:
  format: json
  publish: true
  serverLocation: true
  sentenceForPosition: GPGGA

Field	Description
format	Output format: json (parsed structure) or raw (verbatim NMEA sentence).
publish	Whether to publish parsed messages to $NMEA topics.
serverLocation	Use this NMEA source as the system's location provider.
sentenceForPosition	The sentence type used to extract device/server GPS position.

🧭 Example: If serverLocation: true and sentenceForPosition: GPGGA, the server uses the latest GPGGA sentence to derive its position.

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🧾 Supported NMEA Sentences

The sentences section maps individual NMEA sentence types (e.g., GPGGA, GPRMC) to a structured schema. Each entry defines:

• A human-readable description
• A syntax map that describes each field in the sentence by position

🧬 Field Definitions

Each field within a sentence includes:

• name: Logical name of the data field
• type: Data type (e.g., UTCTime, Position, Enum, long, double, Height)
• param (optional): Enum mappings or special flags
• repeat (optional): Repetition count for array fields

✅ Example: GPGGA

GPGGA:
  description: Global Positioning System Fix Data
  syntax:
    1:
      name: time
      type: UTCTime
    2:
      name: latitude
      type: Position
    3:
      name: longitude
      type: Position
    4:
      name: fix_quality
      type: Enum
      param: '[{"0": "fix not available"}, {"1": "GPS Fix"}, {"2": "Differential GPS fix"}]'
    ...

---

📚 Full List of Supported Sentences

Sentence	Description
GPGGA	GPS Fix Data
GPGLL	Geographic Position (Lat/Lon)
GPGSA	GPS DOP and Active Satellites
GPGSV	Satellites in View
GPHDT	Heading, True
GPRMC	Recommended Minimum Specific GPS/Transit
GPVTG	Track & Speed over Ground
GPZDA	UTC Date and Time

Each of these is parsed into structured fields and published if publish: true is set.

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🧪 Example Output (GPGGA, JSON Format)

Given a raw sentence:

$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47

Parsed result:

{
  "time": "12:35:19",
  "latitude": 48.1173,
  "longitude": 11.5167,
  "fix_quality": "GPS Fix",
  "satellites": 8,
  "hdop": 0.9,
  "altitude": 545.4,
  "height_of_geoid": 46.9
}

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✅ Best Practices

• Use json format for structured parsing and integration with applications.
• Enable publish: true to allow other components or subscribers to access GPS data.
• Use serverLocation: true for location-aware features (e.g., geo-fencing).
• Choose a stable sentence like GPGGA or GPRMC for sentenceForPosition.
• Add only relevant sentences to reduce overhead if parsing all types isn’t needed.

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