VHF Scanner for IC-705

A C# application that monitors your IC-705's built-in scan function, captures audio when squelch opens, transcribes speech using NVIDIA Parakeet ASR (via Sherpa-ONNX), extracts amateur radio callsigns, and sends notifications to Telegram/Discord.

How It Works

┌──────────────────────────────────────────────────────────────────┐
│                      IC-705 (Built-in Scan)                       │
│  • You program memory channels with VHF frequencies              │
│  • You start Memory Scan (SCAN > MEMO)                           │
│  • Radio scans and STOPS when squelch breaks                     │
└───────────────────────────┬──────────────────────────────────────┘
                            │ CI-V (USB Serial)
                            │ • Poll squelch status (15 01)
                            │ • Read frequency when open (03)
                            ▼
┌──────────────────────────────────────────────────────────────────┐
│                         VHF Scanner App                           │
│                                                                    │
│   CI-V Monitor ──► Audio Capture ──► Parakeet ASR                │
│        │                                   │                      │
│        └── Detects squelch open ───────────┘                      │
│                                            │                      │
│                              Callsign Extractor                   │
│                                            │                      │
│                              Telegram / Discord                   │
└──────────────────────────────────────────────────────────────────┘

Features

• 📻 Uses IC-705's native scan - no software frequency stepping
• 🎤 USB audio capture - records when squelch opens
• 🗣️ NVIDIA Parakeet ASR - state-of-the-art speech recognition via Sherpa-ONNX
• 📞 Callsign extraction - recognizes phonetic alphabet ("Fox Four Juliet Zulu Whiskey")
• 📱 Notifications - Telegram, Discord webhooks

Requirements

• .NET 10.0 SDK
• Icom IC-705 connected via USB
• Memory channels programmed with VHF frequencies

Quick Start

1. Configure

Edit appsettings.json:

{
  "Radio": {
    "PortName": "/dev/ttyUSB0",  // or "COM3" on Windows
    "BaudRate": 19200
  },
  "Notifications": {
    "Telegram": {
      "BotToken": "YOUR_BOT_TOKEN",
      "ChatId": "YOUR_CHAT_ID"
    }
  }
}

2. Program IC-705

1. Store VHF frequencies in memory channels (e.g., 2m repeaters, simplex)
2. Set appropriate squelch level

3. Run

cd src/VhfScanner.App
dotnet run

4. Start Scanning

On your IC-705:

• Press SCAN button
• Touch MEMO to start Memory Scan
• The radio will scan through your memory channels and stop when squelch opens

The app will:

1. Detect when squelch opens via CI-V
2. Record the audio transmission
3. Transcribe using Parakeet
4. Extract callsign(s)
5. Send notification

Configuration

Setting	Description	Default
Radio:PortName	Serial port	/dev/ttyUSB0
Radio:BaudRate	CI-V baud rate	19200
Audio:DeviceIndex	Audio device (-1 = auto)	-1
Audio:SampleRate	Capture sample rate	48000
Asr:Model	Parakeet model	sherpa-onnx-nemo-parakeet-tdt-0.6b-v2-int8
Asr:UseGpu	Use CUDA	false
Scanner:PollIntervalMs	CI-V poll rate	50
Scanner:MinCallsignConfidence	Min confidence to notify	0.5

Parakeet Models

The app auto-downloads the Parakeet model on first run (~630MB).

Available models:

• sherpa-onnx-nemo-parakeet-tdt-0.6b-v2-int8 - English only, fast
• sherpa-onnx-nemo-parakeet-tdt-0.6b-v3-int8 - 25 European languages

Telegram Setup

1. Create bot: Message @BotFather → /newbot
2. Get chat ID: Message your bot, visit https://api.telegram.org/bot<TOKEN>/getUpdates
3. For groups: Add bot to group, send a message, check getUpdates for negative chat ID

Example Output

[14:32:15 INF] 📻 Squelch OPEN on 145.5000 MHz
[14:32:22 INF] 📼 Recorded 7.2s transmission
[14:32:23 INF] 🎙️ Transcribing 7.2s audio from 145.5000 MHz
[14:32:24 INF] 📝 Transcription: "CQ CQ CQ this is Fox Four Juliet Zulu Whiskey portable"
[14:32:24 INF] 📞 Detected: F4JZW (confidence: 70%, method: Phonetic)

Files

src/
├── VhfScanner.Core/
│   ├── Radio/
│   │   ├── CivProtocol.cs       # CI-V protocol implementation
│   │   └── Ic705Controller.cs   # IC-705 control
│   ├── Audio/
│   │   ├── AudioCapture.cs      # NAudio USB capture
│   │   └── TransmissionRecorder.cs
│   ├── Asr/
│   │   ├── IAsrService.cs
│   │   ├── ParakeetAsrService.cs  # Sherpa-ONNX Parakeet
│   │   └── CallsignExtractor.cs
│   ├── Notifications/
│   │   └── NotificationServices.cs
│   └── Scanner/
│       └── VhfScannerService.cs  # Main orchestrator
└── VhfScanner.App/
    ├── Program.cs
    └── appsettings.json

License

MIT

73 de F4JZW