GB1153124A - Phase Control Circuit - Google Patents

Abstract

1,153,124. Digital transmission systems; automatic phase control. WESTERN ELECTRIC CO. Inc. 27 May, 1966 [28 May, 1965], No. 23772/66. Headings H3A and H4P. The Specification describes a digital transmission system substantially similar to that described in Specification 1,153,125. The claims relate to the phase control arrangements therein, in which the phase of a clock signal derived from the pilot signals is adjusted by means of a reversible counter controlled by the data and by the preceding starting signals. The received signals pass via the demodulator to an automatic equalizer and thence to a decoding circuit which develops binary signals from the input multilevel signals. During the starting pulses the equalizer sets itself to the required condition and delivers pulses to the reversible counter, the pulses passing to the more significant stages until the derived clock signal is near the correct phase, whereafter they pass to the less significant stages. During reception of data, and provided the bit transition rate is sufficiently high, transition pulses are fed to the least significant stage of the counter. In the event of distortion of the transition distribution curve the pulses are fed to a higher stage. The direction of counting is controlled by a gating arrangement fed by the phasecontrolled clock pulse. The gating arrangement provides clock pulses for the decoding circuit.