This standard specifies air interface of Digital Mobile Communication System employing TDMA (Time Division Multiple Access) system for Local Government TYPE 2 (hereinafter referred to as “Public System”) among narrowband digital telecommunication systems using 260MHz band defined in Article 57-3-2 of the Ordinance Regulating Radio Equipment.

This standard refers to the TETRA (TErrestrial Trunked RAdio) system standardized by ETSI (European Telecommunications Standardization Institute).

In addition, this standard corresponds to the system employing 4-level digital modulation (π/4 shift QPSK) method and having 25kHz channel separation in the above Article of the Ordinance.

This system is composed of control station equipment, base station equipment, fixed station equipment and mobile station equipment in a basic unit of local government (municipality or prefectures). Communications are performed between control station and mobile station (or fixed station), or between mobile station (or fixed station) and mobile station (or fixed station) through base station or directly. Hereinafter communications between mobile station (or fixed station) and mobile station (or fixed station) show the ones through base station (Base station communications). Direct communications between mobile stations show communications not through base station.

In addition, this system employs TDM/TDMA system in which one radio carrier is separated in a frame unit and the frame is divided into 4 slots for obtaining multichannel.