It's true, and radio technology has a lot of inefficiencies in the analog bits. Digital RF techniques help, but the Rx amplifier and downconverters, mixers, an

It's true, and radio technology has a lot of inefficiencies in the analog bits. Digital RF techniques help, but the Rx amplifier and downconverters, mixers, and stuff all lose a lot of energy in the process. Also, the watch has a clock frequency measured in kilohertz, and the processor is probably some dumb as rocks 8051 variant or something with a tiny amount of static RAM. Big difference in power consumption compared to a 32-bit ARM core. Cortex-M0s are pretty competitive with that power regime though these days, especially if your application (like the watch) will allow you to run the M0 at sub-1MHz speeds.