📡 indoor-geolocation-b4a

Android application developed in B4A (Basic for Android) for indoor geolocation systems based on WiFi signals. Designed for educational and research environments focused on geolocation, signal interpolation, and real-time data filtering.

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🚀 Features

The app operates in two working modes:

1. 🔘 Localization OFF Mode (data collection)

• The user manually enters:
  • The scan point (number)
  • The floor/level (G, L1, etc.)
• The app performs a WiFi scan and sends the results as a JSON message to a configured MQTT server.
• Used to build a WiFi fingerprinting database.

2. 🛰️ Localization ON Mode (real-time estimation)

• The app periodically scans for WiFi networks.
• The data is continuously sent to the MQTT server.
• The app subscribes to a topic to receive the estimated position calculated by the external system.
• Can be used to display the user’s estimated position on a map or floorplan.

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🛠️ Development Environment

This project is built using:

✔️ IDE & Tools

• B4A (Basic for Android) version >= 11.80
• B4XPages framework (optional but recommended for modularity)
• Java JDK 11 or later
• Android SDK (API level 29 or higher recommended)

📦 Required Libraries

• MQTT_B4X (based on Eclipse Paho MQTT)
• Network (for connectivity checking)
• Phone (for WiFi scan access)
• JSON (for serialization of messages)
• Timer, StringUtils, etc. (standard B4A libraries)

⚙️ Device Requirements

• Android device with:
  • WiFi scanning capabilities
  • Location permission enabled
  • Android API 21 (Lollipop) or newer

🚀 How to Compile

1. Download and install B4A from b4x.com.
2. Open the indoor-geolocation-b4a.b4a project file.
3. Ensure all required libraries are available in the Libraries tab.
4. Configure your bridge or USB device for deployment.
5. Compile and install on a real device (WiFi scanning does not work on emulators).

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📦 Data Format (JSON Example)

{
  "registro": {
    "manufacturer": "Xiaomi",
    "model": "22111317G",
    "product": "sunstone_eea",
    "sdk": "34",
    "androidID": "0f200264cc00a000",
    "timestamp": 1750756597330,
    "floor": "G",
    "point": 1
  },
  "wifi_scans": [
    {
      "SSID": "wifi_test",
      "BSSID": "00:23:03:00:18:00",
      "security": "WPA2",
      "rssi": -48,
      "channel": 6,
      "distance": 2.46,
      "data_0": 0,
      "data_1": 100,
      "data_2": 2437,
      "data_3": 2427,
      "data_4": 0,
      "data_5": 1,
      "data_6": 1,
      "data_7": 0,
      "data_8": 0,
      "data_9": 0
    }
  ]
}

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🔄 Changes in the Latest Version

• Added automatic handling of GPS activation and location permissions.
• Extended JSON format with device metadata and precise timestamp.
• Introduced RSSI-based distance estimation for each WiFi access point.
• Included extended WiFi scan fields (data_0 to data_9) for advanced signal analysis.
• Refactored and reorganized code for better maintainability and to support future enhancements.