Frederick A Williams

US Patent:

54868670, Jan 23, 1996

Filed:

Nov 30, 1993

Appl. No.:

8/159975

Inventors:

De D. Hsu - San Diego CA
Frederick A. Williams - Bellevue WA
Wendy L. Liu - San Diego CA

Assignee:

Raytheon Company - Lexington MA

International Classification:

H04N 504

US Classification:

348516

Abstract:

A high resolution digital phase detector adapted to receive a threshold value and a sequence of digital samples of a substantially linear portion of an analog video signal. A first output signal is provided when a digital sample is detected as having crossed the threshold value. An interpolation is done between the value of the digital sample to first cross the threshold value and the immediately preceding digital sample on the opposite side of the threshold value. In such manner, the time of the crossing within the sample interval is resolved to a subpixel level. A second output signal represents a fractional phase error between the actual crossing and a desired crossing point within the sample interval. The first and second signals are added in a phase locked loop to adjust the output of a voltage controlled oscillator to be synchronized to the incoming analog video signal in both integer and subpixel phase.

US Patent:

48399060, Jun 13, 1989

Filed:

May 20, 1988

Appl. No.:

7/196235

Inventors:

James H. Leveque - Ellicott City MD
Frederick A. Williams - Encinitas CA
John Eldon - Encinitas CA

Assignee:

AMAF Industries, Inc. - Columbia MD
TRW, Inc. - Cleveland OH

International Classification:

H04L 2700

US Classification:

375 37

Abstract:

A digital linked compressor-expander telecommunications system (Lincompex), is implemented using a general purpose digital signal processor wherein the compression and expansion functions are performed by blocks of programmed code. Input audio analog signals are converted to parallel data digital signals thereupon the digitial signals are input for processing. After processing, the resultant signals are passed to a 16-bit digital-to-analog converter where either the compressed or expanded digital voice data signal is converted back into an audio frequency analog signal for either transmission or communication on an output device.