Understanding Single Pair Ethernet for aircraft networking
Understanding Single Pair Ethernet for aircraft networking
Hey everyone, I recently worked on some printed circuit boards based on a newer industry standard and thought it might interest others. It’s not about your personal gaming PC or anything like that, but you might find it intriguing. I believe a tech enthusiast would appreciate it when ideas run low. Unless you were planning to install fiber optics everywhere—which in the scenarios we’re discussing is impractical—or dealing with the challenges of wireless communication, traditional Ethernet cables remain the go-to for connecting devices. They deliver speed, support up to 10Gbps on Cat6, and allow power delivery alongside data through one cable. In today’s world, from modern vehicles to large factories, networks often need thousands of devices crammed into a small area. The eight twisted pairs in standard Ethernet can be costly and sometimes physically impossible to fit. This led many industry leaders to collaborate with the IEEE, who created a new protocol called single pair Ethernet (SPE). Under this 802.3bp standard, data and power can travel over just two matched conductors, significantly reducing cable size. Most microchips from companies like Microchip operate at 100Mbps but are extremely affordable, with minimal external parts. This makes it easy to set up large sensor networks, run about 3 kilometers of cabling in a car, or link all entertainment systems for movies on airplanes. The connectors used aren’t the usual RJ45 type; instead, they often use a compact two-position locking connector inspired by fiber optic connectors, resulting in smaller switches that connect everything efficiently. You might not notice this standard at home, but there could be a future where a specialized IP camera uses a unique tiny connector rather than the familiar RJ45 jack.
I've contributed to an automotive research lab and participated in projects involving 100Base-T1. I also experimented with a Marvell prototype 1000Base-T1 board. It surprised me when it achieved gigabit speeds over a single pair—until I connected the other side to my laptop and ran an iperf test. The standard I'm most eager about is 802.3cg, which supports only 10Mbps but is designed for bus topologies, making it a suitable alternative to CAN.
Adafruit shared an insightful piece on SPE connectors in their blog. The article highlights the latest developments and offers valuable information for users.