In a segment from a 1971 episode of the BBC science show Tomorrow’s World, host Michael Rodd gave a demo of a pre-recorded cassette tape navigation control apparatus to help motorists find their way. The control device was attached to the cassette player and the car’s odometer, using real-time details through wheel rotations and communicated with a series of beeps to determine distance.
Most of the time the playing unit is switched off it’s only switched on to relay the instructions to me and those times are dictated by this control unit which is mounted underneath the dashboard. On the end of each instruction is recorded a bleep and it’s the precise length of this bleep which tells the control unit how far the car has to travel before the next instructions are due. The cassette player is connected to the control unit here here the control unit is connected to the car mileometer and as my road wheels rotate take me forward, this wheel on the control unit rotates. Now it’s revs are counted and when that count corresponds with the information stored here from the bleep at the end of the last instruction the next instruction is given.