Github.com - Fieldwatch - Receive-only Wi-Fi and Bluetooth LE observer for Android. MIT.

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Fieldwatch Repository Technical Report
Repository URL: GitHub - OffGridPete/Fieldwatch: Receive-only Wi-Fi and Bluetooth LE observer for Android. MIT.
Developer/Owner: OffGridPete (Off Grid Pete LLC)
License: MIT License
Primary Language: Kotlin (99.4%)
Overview
Fieldwatch (formerly known as Spectre up to version 1.2.14) is an open-source, receive-only Wi-Fi and Bluetooth Low Energy (BLE) observer application designed for Android devices. The project is fully local, operating without backend servers, user accounts, internet dependencies, or external hardware dongles. It is built as a lightweight field tool for analyzing and identifying local radio sources directly on-device.
Key Advantages & Features

• 
  Privacy & Offline Architecture
  
  • Runs completely on-device with no external servers, APIs, or telemetry.
    Contains no advertisements or tracking frameworks.[]Does not require user account registration.
  • Receive-Only Passive Scanning
  • Observes local Wi-Fi access points and Bluetooth LE advertisements passively without active injection or packet transmission.
  • Utilizes standard, native Android APIs without requiring root privileges or external radio hardware.
  • Customizable UI & Filtering Engine
  • Offers configurable display views based on target tasks.
  • Includes an integrated filtering engine to reduce noise and isolate specific signals or MAC ranges.
  • Signature Matching & Extensibility
  • Utilizes an integrated signature library (fieldwatch-signatures-v2.json) to identify known radio sources, vendor OUIs, and device characteristics.
  • Allows users to import, export, and customize signatures dynamically.
  • Export & Reporting Capabilities
  • Generates local logs, situational reports, and AI-compatible data exports directly on the phone.
  • Supports local geotagging using device GPS for logged signals.
  • Pre-compiled Deliverables
  • Includes standalone APK builds directly within the repository (dist/Fieldwatch.apk).
  • Provides comprehensive user documentation, including instruction.txt and Fieldwatch_User_Manual.pdf.

Scope & Explicit Limitations

• 
  Not a Packet Sniffer or Monitor Mode Tool: Does not support 802.11 monitor mode, promiscuous mode, or capturing raw frame payloads.[]No Wi-Fi Client/Probe Request Tracking: Only detects visible Access Points (APs) exposed by Android's Wi-Fi scanning API.
  No Bluetooth Classic Support: Operates strictly on Bluetooth LE (BLE); legacy Bluetooth devices (e.g., standard HC-05 modules) will not be visible.[]No Direction Finding: Signal analysis is limited to RSSI levels exposed by the host hardware; it does not perform spatial angle-of-arrival calculations.
• Hardware-Dependent Performance: Detection ranges, update intervals, and scan results are bounded by individual Android device OEM battery management policies, scan quotas, and radio firmware constraints.