Signals training for naval officers

Did naval officers learn only to signal, or also the technology behind it?

They learned the technology as well as signalling procedure, alongside specialist signalmen and other trained personnel.

Kennedy's memoir describes wartime officer training in navigation, rules of the road, gunnery, torpedoes, depth charges, signalling, Morse, and field exercises. Communications instruction did not stop at sending and receiving signals. Officers also learned the underlying technology, alongside specialist signalmen and ratings aboard ship. Effective command depends on understanding both a communication system's operation and its limits.