How to use an external Bluetooth or USB GPS receiver in your browser (online GNSS monitor)

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GNSS Monitor online - sky plot and data panels screenshot

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A step-by-step guide to viewing a live GNSS receiver with GNSS Monitor online - works with Bluetooth and USB receivers, on Android phones and PCs. (What’s under the hood - the Rust/WebAssembly NMEA + u-blox UBX parser - is in the original post.)

On your phone (Bluetooth)

  1. Make sure Bluetooth is turned on and your Bluetooth GNSS receiver is paired in Android’s Bluetooth settings.
  2. Open https://www.clearevo.com/gnss/ in Chrome on Android.
  3. Tap Connect - the picker lists your paired Bluetooth devices. Pick the receiver.
  4. That’s it: live position, fix quality, DOPs, the satellite sky plot and per-satellite SNR bars, right in the browser. No app install. You can also pin the page to your home screen (“Add to Home Screen”) and it opens like an app.

Troubleshooting - paired devices not showing in the Connect dialog: this happened to me when I turned Bluetooth on after Chrome was already running. The fix: fully close Chrome (press the multitask/recents button and swipe Chrome away), reopen the page, and the Bluetooth devices then show up in the picker.

On a PC (USB or Bluetooth)

  1. Plug in your USB/serial GNSS receiver, or pair a Bluetooth one - both show up in the same picker.
  2. Open the page in Chrome or Edge, pick the baud rate if your receiver isn’t at the default 9600, and click Connect.

Reading the display

  • Data panel: latitude/longitude (with an OpenStreetMap link), altitude, fix type, quality, satellites used, DOPs.
  • Sky plot: every satellite in view, colored per constellation (GPS, GLONASS, Galileo, BeiDou…), filled when used in the fix.
  • Signal bars: per-satellite SNR next to the plot.
  • Console: the raw NMEA / u-blox UBX messages as they arrive.

No receiver handy?

Use the two clearly-marked DEMO simulated devices (u-blox-like and MTK-like) - they stream valid NMEA from a fixed position and work in any browser. You can also Open Log to replay an NMEA/UBX log file instead of connecting hardware.

Everything runs client-side - your position never leaves your machine (Google Analytics for visit stats only).

This tool is free software and open source: ykasidit/web_gnss - issues and pull requests welcome.

Full disclosure: this post - and any code or tool it describes - was co-authored with Claude (Anthropic’s AI, via Claude Code). I directed, guided and reviewed. I don’t want to pretend otherwise.

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