METHOD AND APPARATUS TO SYNCHRONIZE MOBILE RADIOS

摘要

A mobile radio (2) is adapted for direct two-way peer-to-peer radio communication with one or more other portable radios (4,6). The radio (2) may be a PMR radio, a Bluetooth radio, a 3G or 4G radio, or another radio communicating on an ad-hoc basis.The radio (2) comprises means (20) for entering into and awakening from a sleep mode, and means (20, 22, 24,26) for generating and transmitting synchronisation signals in a sleep mode. The synchronisation signals are received by one or more other radios (4,6) whereby the radios may become synchronised. When synchronised, the radio (2) may vary the mark: space ratio of its receive period, and may vary the frequency with which it transmits synchronisation signals. The variation may be dependent on the rate at which the radio (2) receives synchronisation signals from other radios (4,6).