Richard C Carickhoff, 82Bradenton, FL

4456890, Jun 26, 1984

Apr 5, 1982

6/365698

Richard C. Carickhoff - Lansdale PA

Computer Peripherals Inc. - Minneapolis MN

H03L 708

331 1A

A clock recovery system including a VCO responsive to a voltage signal for generating a clock signal. A phase detector includes a register and a PROM, the register counting the clock signal to derive the output clock signal. The PROM is responsive to input data and the count in the register to detect and store information concerning relative phase relationships. A counter contains a count from which the control voltage for the VCO is derived. The PROM is operable to alter the count in the counter, thereby performing frequency adjustments, and to alter the count in the register to perform phase adjustments. Also, a converter, operable by the phase detector, may also derive a voltage signal for damping purposes.

4694259, Sep 15, 1987

Sep 29, 1986

6/912879

Richard C. Carickhoff - Lansdale PA
Hakan O. Hemdal - West Chester PA
Alvin L. Schultz - East Greenville PA

Laser Magnetic Storage International Company - Colorado Springs CO

H03L 708

331 1A

A clock recovery and data separator system of the type described in U. S. Pat. No. 4,456,890 is improved by the inclusion of a detector for detecting the trend of instantaneous media speed variation (ISV). The system includes a phase locked loop in which the ISV trend detector is placed between the output of the phase detector and the input of an up/down counter whose output is passed through a digital to analog converter to control the VCO. The ISV trend detector provides a signal which partially compensates phase shift, thereby permitting rapid data recovery performance.