Wow@Home Turns a Low-Cost SDR and a Raspberry Pi 5 Into a Radio Telescope for Alien-Spotting
Build your own little "Big Ear" and see if you can replicate the Wow! Signal of the 1970s.
Researchers from the University of Puerto Rico at Arecibo are looking to build a network of low-cost radio telescopes based on software-defined radio (SDR) dongles — in the hope of turning them into a cost-effective equivalent to the Big Ear telescope used to listen for alien signals in the 1970s.
"A network of small radio telescopes offers several distinct advantages compared to large professional observatories," the team explains of the project, dubbed Wow@Home after the famous SETI@Home distributed computing project. "These systems are low-cost and can operate autonomously around the clock, making them ideal for continuous monitoring of transient events or long-duration signals that professional telescopes cannot commit to observing full-time."
The Wow@Home project is based on low-cost consumer-grade hardware: an RTL-SDR V4 receive-only software-defined radio dongle connected to a Nooelec SAWbird+ H1 low-noise amplifier (LNA) and a mesh satellite dish antenna. The hardware is drive by a Raspberry Pi 5 single-board computer, which helps to keep the overall cost down — around $469 including tools and mounting hardware, excluding the cost of a monitor, keyboard, and mouse.
The project is inspired by the "Big Ear" at Ohio State University, which in August 1977 picked up what became known as the "Wow! Signal" — a strong narrowband signal that was believed to originate in the Sagittarius constellation. While the original Big Ear was shut down in 1997, the Wow@Home equivalent would deliver high scalability at a low cost with no risk of a single point of failure — at, the researchers admit, lower sensitivity.
"The Wow@Home Radio Telescope operates autonomously, 24/7, as a meridian-style instrument, conducting a continuous all-sky survey for transient events," its creators explain. "The hardware required to build these telescopes is both inexpensive and widely accessible, relying on readily available components. The critical element lies in the software, which must be capable of analyzing data effectively, whether from a single station or across a coordinated network of telescopes."
More information on the hardware setup, plus the Easy Radio Astronomy software used to drive it, is available on the project website.