How does the radio alarm clock work? History? Price?

Radio watch is the fifth generation timer after the development of human timing relay hourglass, sundial, mechanical clock and response clock. Wireless watches combine traditional clock technology with high-tech time frequency and electronic technology. It receives the standard time signal sent by the National Time Service Center through long-wave radio, and after being decoded by the built-in microprocessor, it automatically calibrates the timer, so that the time displayed by the radio wave meter automatically keeps accurate synchronization with the standard time maintained by the country. The most famous radio watches should be Casio and Citizen.