For locking a locally generated baud rate clock signal to the baud rate of a received phase-modulated signal, a multiplifer and measuring circuit produces two quadrature phase bi-level channel signals. In each channel signal the two levels over two given periods which are phased apart by 90.degree. are...http://www.google.fr/patents/US4918709?utm_source=gb-gplus-shareBrevet US4918709 - Data demodulator baud clock phase locking
