This Standard provides physical layer performance standards under standard conditions for 12.5 kHz channelization digitally modulated radio equipment with a maximum operating frequency of 1 GHz or less in the Private (Dispatch) Land Mobile Radio Services that employ compatible 4 level frequency modulation (C4FM) or compatible differential offset quadrature phase shift keying (CQPSK) or standard simulcast modulations for systems using digital modulation for transmission of voice or circuit switched data compliant with the U_m reference point in [1], which defines the requirements of both the Physical Layer and the Data Link Layer in the OSI reference model.

Two performance levels have been distinguished herein for certain equipment characteristics. The performance level of Class B is comparable to the performance level for 12.5 kHz analog radio equipment in TIA-603-E, Land Mobile FM or PM Communications Equipment. Class A describes a higher level of performance for more stringent applications.

Use of this standard is encouraged for any application of similar equipment; however, the user should review the required standards needed for the specific application.