GB1292340A - Method of and circuitry for the generation of the timing signal of a pulse sequence and the regeneration of the pulse sequence - Google Patents

Abstract

1292340 Automatic phase control ORION RADIO ES VILLAMOSSAGI VALLALAT 21 Oct 1969 [21 Oct 1968] 51597/69 Heading H3A A system for synchronizing a local clock signal with a received data signal of the type in which the synchronization is effected by controlling a divider which produces the local clock is characterized in that the output signal from the final stage of the divider is divided into a " discrimination" period and a variable length "intervention" period, the length of the latter being adjusted whenever the phase error detected during the discrimination period exceeds a predetermined value and the sense of the adjustment depending on the sign of the phase error. As described with reference to Fig. 2, pulses from oscillator 1 are fed through divide-by-two stage 2, divide-by-five stage 3, and final divide-by-two stage 4 to produce pulses at the required clock rate, and the output from the stage 4 is divided into the. two required periods by gating it with the output from stage 3 in comparator 5. If the phase difference between the input signal 9 and that from the stage 4 is such that a transition of the input signal occurs during the discrimination period, bi-stable 35 is set, thus enabling the logic circuit 31 . . . 34 to produce appropriate signals on lines 19, 20 to change the division factor of stage 2 so that the chain divides by 19 or 21 as required instead of 20.