🕰️ RP1-STRATUM1-NTP-SERVER

August 24.2024

Over the weekend, I built a … thing.

I had a spare Raspberry Pi 4B gathering dust that needed a project. So (in no way influenced by my social media feed), I set out to build a self-hosted GPS-backed NTP server.

By the time I was done, I had a Stratum-1 NTP server with GPS PPS input and microsecond-level accuracy. A fully self-hosted Stratum-1 NTP server using a Raspberry Pi 4B, GPS hat, and PPS signal input — delivering microsecond accuracy from your own home lab.

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📸 What’s Inside

• ✅ Microsecond-accurate time sync (Stratum-1)
• 📡 GPS + PPS integration via Adafruit GPS Hat
• 🐧 Raspberry Pi OS Lite 64-bit
• 🔧 Rebuild-ready scripts and full config exports
• 📁 Project structure includes tooling, configs, documentation, and original blog source

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🧩 Hardware

• Raspberry Pi 4B
• Adafruit Ultimate GPS Hat (product)
• Active GPS antenna (example) with SMA → IPEX adapter
• Pi OS 64-bit Lite + SD card

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🗂️ Repository Structure

.
├── images/              # Photos of hardware setup
├── ntp-configs/         # Exported configs and status snapshots
├── scripts/             # Build, export, and validation tools
├── source_blog/         # Original guide reference (katron.org)
├── LICENSE
└── README.md

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🚀 Quick Start

To set up from scratch or rebuild an existing config:

cd scripts/
sudo ./ntp-toolkit.sh

You'll be presented with a menu to:

1. Build a new NTP server
2. Restore previously exported configs from ntp-configs/
3. Export current live config
4. Run validation tests

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🔁 Restore from Configs

All exported configs and status are located in ntp-configs/:

• chrony.conf – NTP server core config
• gpsd, pps-sources.rules – GPS/PPS integration
• config.txt, cmdline.txt – Pi boot overlays
• chronyc output – time sync & source stability
• ntpshmmon, gpspipe – diagnostics & fix status

Use:

sudo ./scripts/build.sh --restore ./ntp-configs/

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🧪 Run a System Test

To verify GPS lock, PPS detection, and time sync:

cd scripts/
sudo ./test_gps.sh

It checks for:

• PPS device presence
• GPSD and Chrony service status
• GPS fix status via gpspipe
• NTP source tracking and stability

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📷 Images

Photos of the build can be found in images/. A few examples:

• GPS hat mounted to Pi
• Antenna placement
• Terminal output from chronyc, gpsmon, etc.

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📝 Original Build Guide

This project was inspired by Katron.org. Original Post: https://katron.org/blog/2021/10/raspberry-pi-gps/

and if the blog gets taken down, here is a local copy of the page: 📖 katron-rp1-GPS.html

The full referenced files are available in source_blog/katron-rp1-GPS_files/

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📃 License

MIT License – see LICENSE

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⌚ Happy timing from tick.local