Fast PSK carrier recovery in a mobile satellite communication network.

摘要

Supplied with an input signal into which a carrier signal is modulated at a frame period by a data signal and unique words periodically interspersed throughout the data signal, a demodulating circuit (16) quadrature demodulates the input signal into an output signal. A cross-correlating circuit (23) calculates a cross-correlation coefficient between the output signal and a locally known unique word. A frame synchronizing circuit (24) compares the cross-correlation coefficient with a predetermined threshold value and delivers an aperture when the cross-correlation coefficient is below the predetermined threshold value. A phase calculating circuit (25) calculates phase errors between a recovered carrier signal recovered from the output signal and a regenerated carrier signal which is a correct reproduction of the carrier signal. The phase errors are set in a carrier regenerating circuit (17) to render the recovered carrier signal identical with the regenerated carrier signal at the aperture interval. Preferably, a frequency calculating circuit calculates frequency errors between the recovered and the regenerated carrier signals for use in making the recovered carrier signalidentical with the regenerated carrier signal not only as regards phase but also as regards frequency. <IMAGE>