This Standard provides physical layer performance standards under standard conditions for 12.5 kHz channelization digitally modulated radio equipment used in the Private Land Mobile Radio Services that employs a Two-Slot Time Division Multiple Access method for transmission and reception of voice or data using digital techniques, with or without encryption, with a frequency of 1 GHz or less. The definition and description of the system in which this equipment operates is described in [8]. The physical layer description is specified in [5]. The media access control is specified in [6].

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 [7]. Class A describes a higher level of performance for more stringent applications. Should Federal Communications Commission (FCC) requirements as listed in [4], become more stringent than any standard contained herein, the FCC requirements supersede these.

The standards in this document may be applicable to applications other than those specifically addressed in Project 25. Use of these standards is encouraged for any application of similar equipment; however, the user should review the required standards needed for the specific application.