Voltage controlled oscillator with constrained period of frequency change

Claim 2

A voltage controlled oscillator control system receiving an input signal of instantaneous period approximately integrally related to a minimum period comprising: voltage controlled oscillator means responsive to a correction signal to provide a periodic variable frequency output signal determinative of said minimum period; phase comparator means producing an error signal representative of the phase difference between said input signal and said output signal; low pass filter means responsive to said phase comparator means for constraining said oscillator means to adjust its frequency; and timing gate means, connected to said phase comparator means and to said low pass filter means, and responsive to the input signal to permit said filter means to constrain said oscillator means so as to change its output frequency in response to the error signal only for predetermined periods.

Claim 3

The apparatus of claim 1 wherein said phase comparator means comprises: a ramp generator means for producing an increasing signal, said ramp generator means responsive to a predetermined number of said output signal frequency periods to reset said increasing signal to a predetermined signal level; and a sample and hold circuit means responsive to said input signal to store the instantaneous value of said increasing signal.

Claim 4

The apparatus of claim 1 wherein said timing gate means comprises: means responsive to said input signal to generate an enabling signal of a predetermined period; and gate means responsive to said enabling signal to control said low pass filter means in accordance with said enabling signal.

Claim 5

The apparatus of claim 3 wherein said low pass filter means comprises an integrator.

Claim 6

The apparatus of claim 3 wherein said low pass filter means comprises a lag network.

Claim 7

The apparatus of claim 3 additionally comprising input signal transforming means adapted to provide a pulse in response to an input signal cycle.

Claim 8

The apparatus of claim 6 wherein said input signal transforming means comprises a one shot circuit adapted to provide a pulse in response to a relative maximum value of said input signal.

Claim 9

The apparatus of claim 6 wherein said voltage controlled oscillator means produces a pulse train.

Claim 10

A binary magnetic recording recovery system comprising: a moving medium including a magnetizable surface having impressed thereon flux orientations indicative of recorded binary data; a transducer means positioned in close proximity to said surface and responsive to changes in said flux orientations for producing a read signal indicative thereof; detector means responsive to relative maxima of said read signal for producing a train of pulses; and clock signal generation means including; voltage controlled oscillator means responsive to a correction signal for providing a clocking signal, phase comparator means for producing an error signal representative of the phase difference between said train of pulses and said clocking signal, low pass filter means responsive to an applied signal for providing said correction signal to said voltage controlled oscillator, and timing gate means, connected to said phase comparator means and to said low pass filter means, and responsive to said train of pulses and said error signal for providing said applied signal for a predetermined period of time to said low pass filter means.

Claim 11

A binary magnetic recording recovery system comprising: a moving medium including a magnetizable surface having impressed thereon flux orientations indicative of recorded binary data; a transducer means positioned in close proximity to said surface and responsive to changes in said flux orientations for producing a read signal indicative thereof; detector means responsive to relative maxima of said read signal for producing a train of pulses; and clock signal generation means including; voltage controlled oscillator means responsive to a correction signal for providing a clocking signal, phase comparator means for producing an error signal representative of the phase difference between said train of pulses and said clocking signal, low pass filter means responsive to an applied signal for providing said correction signal to said voltage controlled oscillator, and timing gate means, connected to said phase comparator means and to said low pass filter means, and responsive to said train of pulses and said error signal for providing said applied signal for a predetermined period of time to said low pass filter means.

Claim 12

The apparatus of claim 9 further including: flip-flop means responsive to said clocking signal for producing a separation signal; and gate means responsive to said train of pulses and said separation signal for produciNg a ONE data signal.

Claim 13

The magnetic recording recovery system of claim 9 wherein said timing gate means comprises: means responsive to the pulses within said train of pulses for generating an enabling signal of a predetermined period; and gate means responsive to said enabling signal for gating said error signal in accordance with said enabling signal.

Claim 14

A phase lock loop having a periodic output signal of period T and an input signal of variable periods approximately equal to NT where N is a changing integer, comprising: phase comparator means for comparing the difference between the actual period of said input signal and NT to produce an error signal indicative thereof; timing gate means connected to said phase comparator means and responsive to said input signal of variable periods for providing a gated error signal for a predetermined period of time; low pass filter means, connected to said timing gate means and responsive to the gated error signal from said timing gate means, for producing a control signal; and voltage controlled oscillator means for generating said periodic output signal in response to said control signal so as to vary the period T of the periodic output signal.

Claim 15

A phase lock loop having a periodic output signal of period T and an input signal of variable periods approximately equal to NT where N is a changing integer, comprising: phase comparator means for comparing the difference between the actual period of said input signal and NT to produce an error signal indicative thereof; timing gate means connected to said phase comparator means and responsive to said input signal of variable periods for providing a gated error signal for a predetermined period of time; low pass filter means, connected to said timing gate means and responsive to the gated error signal from said timing gate means, for producing a control signal; and voltage controlled oscillator means for generating said periodic output signal in response to said control signal so as to vary the period T of the periodic output signal.

Claim 16

The magnetic recording recovery system of claim 12 wherein said timing gate means comprises: means responsive to the pulses within said train of pulses for generating an enabling signal of a predetermined period; and gate means responsive to said enabling signal for gating said error signal in accordance with said enabling signal.