There is an article in Wiki:
https://en.wikipedia.org/wiki/Rebecc...sponding_radar
My experience was on Vampires. It was never used in anger because we did not have any procedures. The was a pair of ariels above each outer wing and they would vibrate frantically in any icing situation. The instrument was a left/right needle with a range counter. Sometimes it would wander and some numbers would come up.