Gnss_diagnostics

A Flutter plugin that provides real-time GNSS (Global Navigation Satellite System) diagnostic information on Android devices using the native GnssStatus API.

The plugin exposes a broadcast stream that reports:

• Total satellites in view
• Total satellites used in fix
• Per-constellation satellite statistics (GPS, Galileo, GLONASS, BeiDou, etc.)

This is useful for GNSS monitoring, diagnostics, and research applications.

---

Features

• Real-time GNSS satellite status updates.
• Per-constellation breakdown (in-view vs used-in-fix).
• Lightweight, event-based API using EventChannel.
• No polling or background services.
• Designed for diagnostics and visualization.

---

Platform Support

Platform	Support
Android	✅ Yes
iOS	❌ No
Web	❌ No

This plugin currently supports Android only.

---

Installation

Add the dependency to your pubspec.yaml:

dependencies:
  gnss_diagnostics: ^0.1.0

Then run:

flutter pub get

Android Setup

Minimum SDK

Ensure your Android project uses minSdkVersion 24 or higher.

defaultConfig {
    minSdkVersion 24
}

Permissions

Add the following permission to your app’s AndroidManifest.xml:

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

At runtime, you must request location permission before accessing the GNSS stream.

Usage

The plugin exposes a broadcast stream of GnssStatusSnapshot.

import 'package:flutter/material.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:gnss_diagnostics/gnss_diagnostics.dart';

class GnssPage extends StatefulWidget {
  const GnssPage({super.key});

  @override
  State<GnssPage> createState() => _GnssPageState();
}

class _GnssPageState extends State<GnssPage> {
  Stream<GnssStatusSnapshot>? _stream;

  @override
  void initState() {
    super.initState();
    _requestPermission();
  }

  Future<void> _requestPermission() async {
    final status = await Permission.location.request();
    if (status.isGranted) {
      setState(() {
        _stream = GnssDiagnostics.statusStream;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('GNSS Diagnostics')),
      body: _stream == null
          ? const Center(child: Text('Waiting for permission...'))
          : StreamBuilder<GnssStatusSnapshot>(
              stream: _stream,
              builder: (context, snapshot) {
                if (!snapshot.hasData) {
                  return const Center(child: CircularProgressIndicator());
                }

                final status = snapshot.data!;
                return Padding(
                  padding: const EdgeInsets.all(16),
                  child: Text(
                    'Total in view: ${status.totalInView}\n'
                    'Used in fix: ${status.totalUsedInFix}',
                  ),
                );
              },
            ),
    );
  }
}

Notes

• GNSS status callbacks are passive.
• Satellite data may remain zero until:
  • Another app actively requests location updates, or
  • The device acquires a GNSS fix.
• Accuracy and availability depend on device hardware and environment.
• Background execution is not supported.

Example App

A complete working example is provided in the /example directory.

The example demonstrates:

• Runtime permission handling
• Stream consumption
• UI rendering of GNSS constellation data

Use Cases

• GNSS diagnostics and debugging
• Satellite visibility monitoring
• Navigation system analysis
• Educational and research tools
• Field testing GNSS performance on devices