Tetra DMO range extension

摘要

A TETRA device, system, and Direct Mode Operation (DMO) method are presented in which Differential Binary Phase Shift Keying (DBPSK) modulation is used to extend the communication range of direct mode operation TETRA devices. The protocol during various stages of a communication session uses a DBPSK modulation scheme in which one bit is used per symbol and the burst length is twice as long as standard DMO, so that 510 bits are present in consecutive slots. This permits the number of bits per TETRA frame to be the same as standard DMO. The protocol includes specific implementations for ongoing calls, call setup, and master-slave changeover. Although immediate switching between adjacent double slots is not supported using the modulation scheme, the enhanced DMO can use a standard Tetra protocol except for a call setup sequence.