Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1981-11-16
1983-10-04
Heyman, John S.
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
307516, 307527, H03D 1300, H03K 526
Patent
active
044081650
ABSTRACT:
The invention relates to a digital phase detector for use with a phase-locked loop (PLL) system, to which there is fed a reference signal and a comparison signal and which, in accordance with the phase difference transmits an output signal for controlling a voltage-controlled oscillator (VCO). In conventional types of phase detectors there exists the danger that subsequently to a failure or interruption of the reference signal, the phase detector in certain cases controls the phase difference, following the restarting, not to zero but to 2.pi.. In order to prevent this, the invention proposes the phase detector to be preceded by a correction circuit delaying the switching of the signals to the phase detector, following the restarting of the reference signal, in such a way that the trailing edge of the reference signal is applied to the phase detector either simultaneously with or with a time delay after the trailing edge of the comparison signal. In this way, independently of the phase difference, and subsequently to the restarting of the reference signal, it is safeguarded that the phase difference is controlled to zero.
REFERENCES:
patent: 3200340 (1965-08-01), Dunne
patent: 3308387 (1967-03-01), Hackett
patent: 3404230 (1968-10-01), Hailey et al.
patent: 4128812 (1978-12-01), Pavlis
patent: 4309662 (1982-01-01), Baudaux
Heyman John S.
International Standard Electric Corporation
O'Halloran John T.
Seitter Robert P.
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