MPT 1327 protocol extension to 900 MHz

A format designed to allow the operation of the protocol MPT 1327 at 900 MHz is presented. This protocol presents a few problems. One problem is that it is based on the existing signaling format MPT 1317, designed to operate in the frequency margin of 50 to 500 MHz. This limit is due to the low bit rate of the transmission (1200 bauds indirect modulation using fast frequency shift keying (FFSK)). Time diversity is proposed, due to the inherent simplicity of the solution. A novel signaling format is discussed which permits the extension of the use of protocol MPT 1327 to the 900 MHz band with the same reliability within +1 dB as the method applied in lower frequencies (150 MHz). This is done in a simple way, changing the method of modulation of the subcarrier from FFSK to PSK (phase shift keying) to double the bit rate, and using hard time diversity in the channel. Some simulations and experimental tests that show the validity of the approach are presented