GPS NMEA Tether
Android app that turns a phone into a Bluetooth GPS source — built for testing the desktop Dualem mapping application on laptops without onboard GPS, as a lightweight alternative to a full RTK hardware setup.
G PS NMEA Tether turns an Android phone or tablet into a Bluetooth GPS source, streaming standard NMEA 0183 position data to any external device that accepts it. Stephen Taylor built the app for testing the desktop version of the Dualem mapping application, which runs on laptops that lack onboard GPS — and the alternative was an expensive RTK hardware setup. The app provides a lightweight solution: pair a phone over Bluetooth, and the laptop receives standard NMEA position data as if it had its own GPS receiver. It generates and streams NMEA sentences over Bluetooth Classic, with configurable update rates, a live instrument dashboard, an NMEA monitor console, and profiles for different use cases. It runs as a foreground service so streaming continues with the screen off, and includes accessibility features like glove mode and a high-contrast sunlight theme for outdoor fieldwork.
What I did
- Built a full NMEA 0183 sentence generator — GGA, RMC, VTG, GSA, GSV, ZDA — with raw passthrough when available and intelligent fallback generation from Android location data
- Implemented a Bluetooth Classic SPP server with automatic reconnection, backpressure handling, and background streaming via Android foreground service
- Designed a live instrument dashboard with a custom animated fix status indicator, real-time speed, heading, altitude, satellite count, and position displays
- Built an NMEA monitor console with syntax color-coding, sentence filtering, search, throughput display, and log export
- Internationalized the app into nine languages
