Research on Multi-frequency Constant Envelope Multiplexing Technology of Satellite Navigation Signal

Non-linear distortion would be introduced when non-constant envelope signal passes through power amplifiers. In the satellite navigation system, since composite signal generated by direct linear combination of signals does not have constant envelope characteristic, unexpected distortion would be introduced when the composite signal passes through the amplifier located in load transmitter. Therefore, constant envelope processing is necessary for multiple satellite signals of one certain frequency or different frequencies. In this paper, the existing constant envelope multiplexing techniques of multi-frequency, such as AltBOC, TD-AltBOC, POCET and ACED are studied and analyzed. The study shows that the AltBOC signal with constant envelope has strong anti-multipath capability and good tracking performance. On this basis, to realize the constant envelope multiplexing of B1 and L1 signals, a constant envelope modulation method based on AltBOC multiplexing technique is proposed. Simulation shows that this method can realize the constant envelope multiplexing of four signal components with two center frequencies.