| 摘要 |
1,246,374. Multiplex pulse signalling; automatic phase control. NIPPON ELECTRIC CO. Ltd. 22 Oct., 1969 [25 Oct., 1968], No. 51843/69. Headings H3A and H4L. A synchronization system for a plurality of stations in a time division multiplex system comprises at each station, means for detecting phase differences between incoming clock pulse signals and the local clock pulse signals, a counter for measuring the phase differences digitally, means for determining the differences between the measured phase differences and a preset reference phase and means for weighting and averaging the differences to control the insertion or deletion of pulses into or from the local clock pulse train. As shown in Fig. 3 incoming clock signals 53 to 56 are supplied to phase comparators 31 to 34 respectively and compared with the local clock pulses on line 57. The phase comparators may be bi-stable devices which are set by one of the inputs and reset by the other to produce duration modulated pulses which operate counters 35 to 38 receiving pulses from a clock pulse generator 39 to produce corresponding digital outputs. The outputs of the counters are stored at 40 to 43 respectively and compared at 44 to 47 with a digital reference phase value from a generator 48, circuits 44 to 47 producing signals indicating whether the measured phase is equal to, larger than, or smaller than the reference phase. These signals are supplied to a logic circuit 49 where they are treated in terms of " majority decision " certain stations being arranged to carry a larger weight in the decision. The judged result is applied to a control circuit 50 which inserts or removes pulses from the clock pulse train generated at 51 as required, the resulting sharp phase variations being removed in circuit 52 which may take the form of a phase controlled oscillator. |
