Research and implement of carrier synchronization based on square phase-locked loop

Theory of coherent demodulation based on method of square counterchange is introduced in this article. Square phase-locked loop (PLL) is proposed to achieve coherent carrier from 2DPSK signal. The 180° phase´s inexplicit problem which exists in carrier recovery is resolved. It improves the resisting noise property of communication system. We scheme out emulational circuit diagram for carrier distilling with PLL by using simulink and process corresponding emulational experiment. Experimental results show that our method can extracts carrier perfectly.