Pile-Up Control System

PUCS: Take control of the pile-up!

by SANDER PD9HIX and ERWIN PA3EFR VAN DER HAAR

Every special event station (SES) operator knows the thrill — and the chaos — of a true pile-up. The excitement of dozens of stations calling you simultaneously can quickly turn into frustration when QRM, doubles, and missed calls clutter the frequency. Wouldn’t it be great if there were a way to bring order to that chaos without losing the fun of real-time operating?

Enter PUCS, the Pile-Up Control System, a fully open-source, web-based platform designed by and for radio amateurs. Born from the ingenuity of the Radio Scouting Fellowship PA3EFR/J, PUCS elegantly blends traditional ham ingenuity with modern AI-assisted software development. The result is a modular, flexible system that any club or individual can tailor to their own operating style — from large-scale SES activities to small club field days.

PUCS can be seen operational at pucs.pa3efr.nl

From Normandy to the Netherlands

The idea for PUCS was sparked during an SES operation on the beaches of Normandy, where operators of TM80DDAY overheard multiple Australian colleagues discussing a private sign-up system for QSOs. Intrigued but unable to obtain the software, Erwin PA3EFR and his team decided to build their own version — and then share it freely with the world. With the help of AI tools and some Python wizard Barry, PC1K, PUCS was born. It was much later when Erwin decided to develop PUCS within his own environment.

Today, PUCS is freely available, fully documented, and open to anyone willing to experiment. It’s more than just software — it’s an invitation to collaborate, learn, and contribute to a smarter way of managing pile-ups.

What Makes PUCS Unique

At its heart, PUCS is a distributed system consisting of two parts:

• Frontend (commercial hosting): This is the public entry point where operators register their callsigns to join the queue. Think of it as a digital “waiting room” — transparent, fair, and visible to everyone.  
• Backend (local PC): Here’s where the magic happens. The backend checks QRZ.com logbooks every minute, automatically removes callsigns that have already been worked, and provides an admin dashboard to manage the queue, export logs, and adjust settings on the fly.

The system uses Python’s Flask framework, SQLite databases, and SocketIO for real-time updates — all standard, well-documented technologies familiar to many technically minded amateurs. It’s simple enough for a club to host on a modest PC, yet robust enough to handle large SES events.

Open Source, Open Spirit

PUCS is more than a tool — it’s a philosophy. The creators explicitly invite others to modify, enhance, and restyle the system to their own preferences. Whether you want to change the interface colors, add logging features, integrate digital modes, or redesign the operator dashboard, the code is yours to explore. There’s no hidden agenda, no locked components — just open code and open collaboration.
All scripts, examples, and documentation are available on GitHub:

https://github.com/PA3EFR/PUCS

Why You Should Try It

PUCS is a perfect project for your club’s next technical workshop. It offers practical lessons in networking, APIs, databases, and web hosting — all wrapped around a real amateur radio application. 
Beyond that, it promotes fairness in pile-ups, gives weaker stations a chance to make contact, and even allows SWLs to log their participation.

So fire up your soldering iron if you must, but this time, your “kit” is made of code.
Download PUCS, make it your own, and bring calm to your next pile-up.

As Erwin, PA3EFR, says: “Ask AI as your friend for support — and enjoy your own moments of challenge!” On behalf of the Radio Scouting Fellowship PA3EFR/J we look forward to see you on our PUCS screens at a next special event occasion.

~ Sander PD9HIX