M79 Mounted w/ Radar Device (1960's) ( lemmy.world )
The 40mm M79 Grenade Launcher used by the US famously in Vietnam, and in conflicts after that, had a radar system made by the Radio Corporation of America that would give an audio que to denote target range and speed. Almost like a mix of a policeman's speedometer and a range finder, on a grenade launcher. It apparently worked up to 500 meters.
https://lemmy.world/pictrs/image/e23256fb-ee45-437c-ab7e-64be46bed881.jpeg