GB1072929A - Synchronization system for p.c.m. transmission - Google Patents

Abstract

1,072,929. Multiplex pulse code signalling. HITACHI SEISAKUSHO KABUSHIKI KAISHA. Dec. 17, 1963 [Dec. 18, 1962 (2)], No. 49808/63. Heading H4L. Two time division multiplex pulse code modulation systems, each having independent timing circuits, are interconnected by the use of an automatically adjustable delay means, the delay being continuously adjusted and one frame being periodically repeated or missed according to the relationship between the two frequencies. In one arrangement, Fig. 4, a magnetostrictive delay line MD is provided with an input circuit W receiving signals S B from a remote station B, and two output circuits R 1 R 2 , the circuit W being movable along the delay line under the control of a comparator S c receiving framing signal F Ba selected at F D from the output S Ba at terminal 42, and the locally generated framing signals F A . An electronic switch SW selects via gate G 1 or G 2 which output R 1 or R 2 is in use by switching over the output when the circuit W reaches point P 1 or P 2 . The length of the delay line is such that the signals obtained from R 1 and R 2 differ by one frame. An ultrasonic delay line which may be of circular or semicircular form may be used. In the case of the parallel transmission of p.c.m. signals an adjustable delay line is provided for each of the parallel channels, the delay lines being controlled by a common adjusting means.