In-Car Sat Nav? Without a Satellite? In 1971? | Tomorrow's World | Retro Tech | BBC Archive

A prototype navigation system utilizes pre-recorded cassette tapes and a dashboard-mounted control unit to provide precise, real-time driving directions. Unlike human pedestrians who may offer confusing advice, this technology synchronizes audio instructions with the car's odometer, triggering specific commands based on the distance traveled and the vehicle's tire size. Testing over a 20-mile route in Kent demonstrated an accuracy within 30 yards, regardless of driving style or speed. Potential applications include assisting international tourists in rental cars through multi-language programming and training bus drivers on new routes. However, the system lacks flexibility; because it relies on pre-recorded data, any unprogrammed roadworks or diversions can lead the driver off-course, turning a guided journey into a "mystery tour."