GPSd

GPSD is an open-source daemon for Unix-like systems that monitors one or more Global Positioning System (GPS) receivers connected to a computer. It abstracts device-specific details and provides a consistent interface for applications to access positioning, timing, and satellite visibility data without needing to parse individual device output themselves.

GPSD collects data from receivers through common interfaces such as serial ports, USB, or network connections and supports multiple receiver protocols, primarily NMEA. It aggregates information into data classes such as TPV (Time-Position-Velocity), SKY (satellite visibility), and ATT (attitude). The daemon serves this information to clients via a network socket (default port 2947) using a machine-readable protocol, typically JSON, as well as human-readable streams for debugging.

Multiple clients can connect to gpsd simultaneously, enabling sharing of GPS data across applications, dashboards, or logging tools. The daemon can auto-detect devices, monitor their status, and handle PPS timing signals when available. Common user-facing utilities such as cgps, gpsmon, and xgps act as clients to gpsd, illustrating the separation between data collection and consumer software.

gpsd is widely used in Linux distributions and other Unix-like systems and is maintained by an open-source community. It is suitable for navigation, surveying, robotics, and embedded devices, where reliable access to GPS timing and positioning information is important.