555-based radio paging system circuit

The radio paging system is a one-way selective calling system without voice. The receiving end is a plurality of high-sensitivity receivers (commonly known as pocket bells) that can be carried by users. When the receiver receives a call, it automatically rings, displays digital or Chinese characters, and delivers specific information to the user. The paging receiver has a small appearance, but the internal is a complete radio receiver. Its working principle is the same as that of a normal radio station. It is generally composed of two parts: a radio frequency receiving unit and a logic control unit. The RF receiving unit is composed of an antenna, a high-amplitude, a mixing, a mid-amplifier and a filtering, a limiting amplification and a frequency discrimination circuit. The logic control unit is composed of a microprocessor, a decoder, an integrated function interface component, an address and function data memory, a liquid crystal display and a booster circuit. Generally required to be small in size, low in power consumption, high in reliability, easy to carry, and has good dustproof, shockproof and impact resistance. In addition to audio pagers, there are digital display pagers and Chinese character display pagers. Now China's radio paging has evolved from a local paging network to a regional paging network, and gradually formed a national paging network. A simple paging system consists of three parts: a paging center, a base station, and a paging receiver. The figure below shows the radio paging system circuit.

Radio paging system circuit diagram