Method and apparatus for providing an uninterrupted clock signal

Details Method and apparatus for providing an uninterrupted clock signal Method and apparatus for providing an uninterrupted clock signal

1992-06-26

1994-12-06

Bocure, Tesfaldet

Pulse or digital communications

Spread spectrum

Direct sequence

375120, 331 49, 307 23, 307 65, 307 80, H04L 700

Patent

active

053717643

ABSTRACT:
A digital computer is provided having a clock generation circuit for generating a clock signal in response to an input signal from a fixed-frequency oscillator, which includes a first fixed-frequency oscillator and a second fixed-frequency oscillator, each providing an output signal. Also included is failure detection circuit for detecting a failure of either of the fixed-frequency oscillators, wherein a failure occurs when the first fixed-frequency oscillator or the second fixed-frequency oscillator ceases generating an output. A circuit synchronizing the output from the oscillators is coupled to both the first fixed-frequency oscillator and to the second fixed-frequency oscillator. This synchronizing circuit modifies the output from the second fixed-frequency oscillator to produce a synchronized output that is substantially synchronous with the output from the first fixed frequency oscillator. A switching circuit is coupled to the failure detection circuit, the output from the first fixed-frequency oscillator and the synchronized output of the second fixed-frequently oscillator. The switching circuit normally couples the output of the first fixed-frequency oscillator as the clock signal and wherein in response to a detection of a failure of the first fixed-frequency oscillator, the synchronized output is provided as the clock signal.

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