Hangup corrector useful in locked loop tuning system

Details Hangup corrector useful in locked loop tuning system Hangup corrector useful in locked loop tuning system

1978-05-11

1980-08-19

Bookbinder, Marc E.

Telecommunications

Receiver or analog modulated signal frequency converter

Signal selection based on frequency

331 10, 331 17, 331 18, 455260, H04B 126, H03B 306

Patent

active

042186579

ABSTRACT:
A phase locked loop tuning system for a television receiver includes a reference oscillator, a reference divider for dividing the frequency of the output signal of the reference oscillator, a voltage controlled local oscillator, a prescaler for dividing the frequency of the output signal of the local oscillator by a predetermined factor, a programmable divider for dividing the frequency of the output signal of the prescaler by a factor determined by the presently selected channel, a phase comparator for generating a series of pulses representing the phase and frequency relationships between the output signal of the reference divider and the output signal of the programmable divider and a low pass filter for deriving a control voltage for the local oscillator in response to the pulses generated by the phase comparator. The pulses generated by the phase comparator have polarities and widths dependent on the sense of the phase and/or frequency differences between the output signals of the reference divider and the programmable divider. A lock detector determines whether the pulses generated by the phase comparator have widths less than a first predetermined width at the end of a predetermined time. If the output signal of the prescaler has an incorrect frequency in response to a temporary malfunction of a component within the loop, the pulses generated by the phase comparator will not have widths less than the first predetermined width. In response to this occurrence, a mode switch decouples the pulses generated by the phase comparator from the low pass filter and couples pulses having a predetermined duty cycle, a predetermined repetition rate and the opposite polarity to the low pass filter instead. When the lock detector determines the first time one of its output pulses has a width less than a second predetermined width, narrower than the first, the pulses generated by the phase comparator are again coupled to the low pass filter.

REFERENCES:
patent: 3958186 (1975-03-01), Jesse et al.
patent: 3971991 (1976-07-01), Tanaka
patent: 4000476 (1976-12-01), Walker et al.
patent: 4077016 (1978-02-01), Sanders et al.
patent: 4100503 (1978-07-01), Lindsey et al.
patent: 4131862 (1978-12-01), Black
"A New Design Technique For Digital P.L.L. Synthesizers"-Eric Breeze Feb. 1978-IEEE Trans. on Consumer Elctronics, vol. CE 24, No. 1 pp. 24-33.

Affiliated with

Also associated with

Rating

Hangup corrector useful in locked loop tuning system does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Hangup corrector useful in locked loop tuning system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hangup corrector useful in locked loop tuning system will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1429345