Simple APRS iGate with RTL-SDR

A minimal, cost-effective APRS iGate setup using RTL-SDR for receive-only operation. Perfect for amateur radio operators wanting to contribute to the APRS network with minimal investment.

🚀 Features

• Ultra Low Cost: ~€50 total hardware cost
• Receive-Only: No RF transmission, just monitoring and forwarding
• Docker Based: Easy deployment and maintenance
• Minimal Hardware: Raspberry Pi Zero + RTL-SDR dongle
• Professional APRS Integration: Connects to APRS-IS servers
• Remote Monitoring: TCP interface for live packet viewing

📋 Hardware Requirements

Component	Cost (approx)	Description
Raspberry Pi Zero W	€20-25	ARM processor with WiFi
RTL-SDR Dongle	€15-20	RTL2832U chipset
VHF Antenna	€5-10	144-148MHz optimized

🔧 Quick Start

Prerequisites

• Valid Amateur Radio License with callsign
• Linux system with Docker and Docker Compose installed
• APRS-IS passcode (get from apps.magicbug.co.uk)

1. Clone Repository

git clone https://github.com/N1k0droid/simple-aprs-igate.git
cd simple-aprs-igate

2. Configure Your Station

# Copy sample configuration
cp .env.sample .env

# Edit with your details
nano .env

Required Settings:

APRS_CALLSIGN=W1ABC-10      # Your callsign + SSID
APRS_PASSCODE=12345         # Your APRS-IS passcode
LATITUDE=40.7128            # Your GPS coordinates
LONGITUDE=-74.0060

3. Deploy iGate

# Build Docker image
docker compose build

# Start iGate service
docker compose up -d

# Monitor startup
docker logs -f aprs-igate

4. Verify Operation

# View live APRS packets
./scripts/igate_manager.sh packets

# Check iGate status
./scripts/igate_manager.sh status

# View on APRS.fi - search for YOUR_CALL-10

📊 Expected Results

Once operational, you should see:

Console Output:

[0] W1ABC>APRS,WIDE1-1:!4208.75N/07115.12W>Mobile Station
[0] << [IG] W1ABC>APRS,WIDE1-1:!4208.75N/07115.12W>Mobile Station

APRS.fi Integration:

• Your iGate appearing on the map with coverage radius
• Local RF traffic forwarded to Internet
• Received stations showing "via YOUR-CALL-10"

🛠 Management Commands

# Start iGate
./scripts/igate_manager.sh start

# Stop iGate
./scripts/igate_manager.sh stop

# Restart (after config changes)
./scripts/igate_manager.sh restart

# View logs
./scripts/igate_manager.sh logs

# Monitor packets
./scripts/igate_manager.sh packets

# Check status
./scripts/igate_manager.sh status

⚙️ Configuration Options

Edit .env file to customize your iGate:

Variable	Description	Example	Required
APRS_CALLSIGN	Your callsign + SSID	W1ABC-10	✅
APRS_PASSCODE	APRS-IS passcode	12345	✅
LATITUDE	GPS latitude (decimal)	40.7128	✅
LONGITUDE	GPS longitude (decimal)	-74.0060	✅
APRS_SERVER	APRS-IS server	euro.aprs2.net	No
FILTER_RADIUS	Geographic filter (km)	100	No
RTL_PPM	Frequency correction	0	No

Regional Server Settings

Region	Server	Port
Europe	euro.aprs2.net	14580
North America	noam.aprs2.net	14580
Asia-Pacific	asia.aprs2.net	14580
Global	rotate.aprs2.net	14580

📡 Technical Details

Frequency Configuration

• Europe: 144.800MHz
• North America: 144.390MHz
• Modulation: AFSK 1200 baud
• Sample Rate: 22.05 kHz

APRS-IS Integration

• Protocol: APRS-IS TCP
• Geographic Filtering: Configurable radius
• Beacon Interval: 30 minutes
• Packet Forwarding: RF → Internet only

Power Consumption

• Raspberry Pi Zero W: ~0.7W
• RTL-SDR: ~0.3W
• Total: ~1W (suitable for solar power)

🏗 Architecture

APRS RF (144.800MHz) → RTL-SDR → rtl_fm → Direwolf → APRS-IS → aprs.fi

Software Components

• rtl_fm: RTL-SDR demodulation
• Direwolf: APRS packet decode/encode
• Docker: Containerized deployment
• Ubuntu 22.04: Base system

🔍 Troubleshooting

No Packets Received

# Test RTL-SDR access
docker exec -it aprs-igate rtl_test -t

# Expected output: RTL-SDR device detected

Common Issues:

• Antenna not connected or poorly positioned
• No local APRS activity (verify with handheld radio)
• RTL-SDR device not accessible to container

Connection Issues

# Verify callsign and passcode
cat .env | grep APRS_

# Test internet connectivity
ping euro.aprs2.net

Common Issues:

• Invalid APRS passcode
• Firewall blocking port 14580
• Network connectivity problems

Container Problems

# View detailed logs
docker logs aprs-igate

# Rebuild container
docker compose build --no-cache

# Check Docker system
docker system info

RTL-SDR Calibration

# Check frequency accuracy
rtl_test -p

# Run for 5-10 minutes and note PPM error
# Add the PPM value to your .env file

🌐 APRS Network Integration

Your iGate contributes to the global APRS network by:

1. Receiving local APRS packets on VHF frequency
2. Decoding packets using professional Direwolf TNC software
3. Forwarding to APRS-IS servers for global distribution
4. Publishing position beacon showing iGate location and coverage

Coverage Display

Your iGate will appear on aprs.fi with:

• Gateway symbol (diamond with "R" overlay)
• Position beacon every 30 minutes
• Coverage radius based on received stations
• Statistics showing packets forwarded

Development

# Build development image
docker compose build

# Run with logs
docker compose up

# Test configuration changes
./scripts/igate_manager.sh restart

📜 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Direwolf - Professional APRS TNC software by WB2OSZ
• RTL-SDR - Affordable SDR hardware enabling this project
• APRS-IS - Internet backbone of the APRS network
• Amateur Radio Community - For developing and maintaining APRS

---

73 & Happy DXing! 📻