The transponder delay was sufficient for the Gemini radar to switch from transmit to receive; the radar would then subtract the delay time to calculate range and relative speed, or range rate ...

In the normal NASA redundant manner, they also had a microwave C-band (4.5GHz) radar system for tracking missile tests, and improved it for use with Apollo at lunar ranges.

(In this science fiction world, Radar landed on the lunar surface in 1957, well before the 1969 Apollo 11 moon landing.) The 7-minute-video is based on the "Dr. Connie Radar PhD" comic strip and ...