# INTERCEPT

<p align="center">
  <img src="https://img.shields.io/badge/python-3.7+-blue.svg" alt="Python 3.7+">
  <img src="https://img.shields.io/badge/license-MIT-green.svg" alt="MIT License">
  <img src="https://img.shields.io/badge/platform-macOS%20%7C%20Linux-lightgrey.svg" alt="Platform">
  <img src="https://img.shields.io/badge/author-smittix-cyan.svg" alt="Author">
</p>

<p align="center">
  <strong>Signal Intelligence</strong>
</p>

<p align="center">
  A sleek, modern web-based front-end for RTL-SDR signal decoding tools.<br>
  Provides a unified interface for multimon-ng (POCSAG/FLEX) and rtl_433 (433MHz sensors).
</p>

## Screenshot
<img src="screenshot.png">

---

## What is INTERCEPT?

INTERCEPT is a **web-based front-end** that provides a unified, modern interface for popular RTL-SDR signal decoding tools:

- **rtl_fm + multimon-ng** - For decoding POCSAG and FLEX pager signals
- **rtl_433** - For decoding 433MHz ISM band devices (weather stations, sensors, etc.)

Instead of running command-line tools manually, INTERCEPT handles the process management, output parsing, and presents decoded data in a clean, real-time web interface.

---

## Features

### Pager Decoding
- **Real-time decoding** of POCSAG (512/1200/2400) and FLEX protocols
- **Customizable frequency presets** stored in browser
- **Auto-restart** on frequency change while decoding

### 433MHz Sensor Decoding
- **200+ device protocols** supported via rtl_433
- **Weather stations** - temperature, humidity, wind, rain
- **TPMS** - Tire pressure monitoring sensors
- **Doorbells, remotes, and IoT devices**
- **Smart meters** and utility monitors

### General
- **Web-based interface** - no desktop app needed
- **Live message streaming** via Server-Sent Events (SSE)
- **Audio alerts** with mute toggle
- **Message export** to CSV/JSON
- **Signal activity meter** and waterfall display
- **Message logging** to file with timestamps
- **RTL-SDR device detection** and selection
- **Configurable gain and PPM correction**


## Requirements

### Hardware
- RTL-SDR compatible dongle (RTL2832U based)

### Software
- Python 3.7+
- Flask
- rtl-sdr tools (`rtl_fm`)
- multimon-ng (for pager decoding)
- rtl_433 (for 433MHz sensor decoding)

## Installation

### 1. Install RTL-SDR tools

**macOS (Homebrew):**
```bash
brew install rtl-sdr
```

**Ubuntu/Debian:**
```bash
sudo apt-get install rtl-sdr
```

**Arch Linux:**
```bash
sudo pacman -S rtl-sdr
```

### 2. Install multimon-ng

**macOS (Homebrew):**
```bash
brew install multimon-ng
```

**Ubuntu/Debian:**
```bash
sudo apt-get install multimon-ng
```

**From source:**
```bash
git clone https://github.com/EliasOenal/multimon-ng.git
cd multimon-ng
mkdir build && cd build
cmake ..
make
sudo make install
```

### 3. Install rtl_433 (optional, for 433MHz sensors)

**macOS (Homebrew):**
```bash
brew install rtl_433
```

**Ubuntu/Debian:**
```bash
sudo apt-get install rtl-433
```

**From source:**
```bash
git clone https://github.com/merbanan/rtl_433.git
cd rtl_433
mkdir build && cd build
cmake ..
make
sudo make install
```

### 4. Install Python dependencies

```bash
pip install -r requirements.txt
```

### 5. Clone and run

```bash
git clone https://github.com/yourusername/intercept.git
cd intercept
python3 intercept.py
```

Open your browser to `http://localhost:5050`

## Usage

1. **Select Device** - Choose your RTL-SDR device from the dropdown
2. **Set Frequency** - Enter a frequency in MHz or use a preset
3. **Choose Protocols** - Select which protocols to decode (POCSAG/FLEX)
4. **Adjust Settings** - Set gain, squelch, and PPM correction as needed
5. **Start Decoding** - Click the green "Start Decoding" button
6. **View Messages** - Decoded messages appear in real-time in the output panel

### Frequency Presets

- Click a preset button to quickly set a frequency
- Add custom presets using the input field and "Add" button
- Right-click a preset to remove it
- Click "Reset to Defaults" to restore default frequencies

### Message Logging

Enable logging in the Logging section to save decoded messages to a file. Messages are saved with timestamp, protocol, address, and content.

## Default Frequencies

### Pager (UK)
- **153.350 MHz** - UK pager frequency
- **153.025 MHz** - UK pager frequency

### 433MHz Sensors
- **433.92 MHz** - EU/UK ISM band (most common)
- **315.00 MHz** - US ISM band
- **868.00 MHz** - EU ISM band
- **915.00 MHz** - US ISM band

You can customize pager presets in the web interface.

## API Endpoints

| Endpoint | Method | Description |
|----------|--------|-------------|
| `/` | GET | Main web interface |
| `/devices` | GET | List RTL-SDR devices |
| `/start` | POST | Start pager decoding |
| `/stop` | POST | Stop pager decoding |
| `/start_sensor` | POST | Start 433MHz sensor listening |
| `/stop_sensor` | POST | Stop 433MHz sensor listening |
| `/status` | GET | Get decoder status |
| `/stream` | GET | SSE stream for pager messages |
| `/stream_sensor` | GET | SSE stream for sensor data |
| `/logging` | POST | Toggle message logging |
| `/killall` | POST | Kill all decoder processes |

## Troubleshooting

### No devices found
- Ensure your RTL-SDR is plugged in
- Check `rtl_test` works from command line
- On Linux, you may need to blacklist the DVB-T driver

### No messages appearing
- Verify the frequency is correct for your area
- Adjust the gain (try 30-40 dB)
- Check that pager services are active in your area
- Ensure antenna is connected

### Device busy error
- Click "Kill All Processes" to stop any stale processes
- Unplug and replug the RTL-SDR device

## License

MIT License - see [LICENSE](LICENSE) for details.

## Author

Created by **smittix** - [GitHub](https://github.com/smittix)

## Acknowledgments

- [rtl-sdr](https://osmocom.org/projects/rtl-sdr/wiki) - RTL-SDR drivers
- [multimon-ng](https://github.com/EliasOenal/multimon-ng) - Multi-protocol pager decoder
- [rtl_433](https://github.com/merbanan/rtl_433) - 433MHz sensor decoder
- Inspired by the SpaceX mission control aesthetic

## Disclaimer

This software is for educational and authorized use only. Ensure you comply with local laws regarding radio reception and privacy. Intercepting private communications without authorization may be illegal in your jurisdiction.