I recently learned about CATS from the excellent Zero Retries by Steve Stroh (you should subscribe, its an excellent newsletter). To quote from the CATS documentation:

At its core, CATS is a packet radio standard primarily designed for autonomous position reports, but is versatile enough to support a much wider scope of communication. CATS packets are extremely versatile, consisting of multiple “Whiskers” which make up the packet. Whiskers come in several types. For example, a typical CATS position beacon would likely contain an Identification Whisker, GPS Whisker, and potentially a Comment Whisker and Timestamp Whisker. Different Whiskers can be mixed and matched to allow a wide range of data to be encoded. Detailed information on CATS can be found in the standard, linked below.

Stephen’s goal is to build a modern replacement for APRS with quite a few improvements. CATS uses FSK rather than FM, has a faster data rate (9600baud), and has forward error correction. CATS uses 70cm rather than the 2m that is more common with APRS.

The project is still work-in-progress, but there has been tremendeous progress already. There is a well-documented standard, reference implementations written in rust, and a design for a standalone transciever. The rust implementation is interesting to me as it is easy to use rust projects in python (my preferred language).

I’m not currently running any CATS at my shack, but will be watching the project. The cat puns alone are enough to keep my interest!