Compression Labs, Inc.

Texas Instruments Corporation

Lyle V Rennick

Robert H Wallis

Ronald S Bader

Wen-hsiung Chen

William K Pratt

A phase-locked loop (PLL), particularly useful for ADSL frequency locking applications, uses inexpensive external components in combination with versatile logic that can be implemented in a programmable logic device or an application specific integrated circuit. The PLL has the ability to revert to center-frequency operation in the absence of a timing reference and to adapt to a variety of reference frequencies through logic selection.

Phase-locked loop for ADSL frequency locking applications

A dual mode facsimile data compression technique which possesses the advantage of symbol recognition and extended run-length coding methods. In operation, a symbol blocking operator isolates digital raster data representing valid alphanumeric characters and document symbols. The first symbol encoungered is placed in a memory or library and as each new symbol is detected, it is compared with each entry of the library. If the comparison is within a predetermined tolerance, a library identification code representing the symbol is generated and transmitted along with the symbol location coordinates. Otherwise, the new symbol is placed in the library and its digital pattern and location is transmitted. A scoring system determines which elements of the library are to be replaced by new prototypes once the library is filled. Non-isolated symbols are coded by a two-dimensional run-length coding method for transmission.

Dual mode facsimile coding system and method

A high speed character matcher and method for measuring the similarity between a pair of binary patterns representing two-dimensional images. The patterns are compared on a bit by bit basis and when a discrepancy is detected, it is assigned an error penalty which is based on the two-dimensional context in which the error occurred. The types of error context which are typical in the comparison of distorted but otherwise similar characters are given a lower error than those typically encountered in the comparison of dissimilar characters.

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Cupertino, CA, United States of America

Lyle V Rennick