The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 13, 1981
Filed:
Nov. 14, 1979
Martin L Resnick, Chestnut Hill, MA (US);
GTE Laboratories Incorporated, Waltham, MA (US);
Abstract
A data processing apparatus for receiving and processing coded words each word including, in succession, a reference bit, a start bit, data or command bits, a flag bit, a stop bit and a parity bit. The various bits are encoded within a corresponding number of bit periods by eighteen cycles of a 900 hertz signal. The start bit is reversed in phase with respect to the phase of the reference bit to represent a logic '0' and each of the additional bits is either reversed in phase or not reversed in phase with respect to the preceding bit thereby to represent a logic '0' or logic '1', respectively. The data processing apparatus in accordance with the invention includes a microprocessor which performs multiple sampling and frequency comparison operations on each coded word to detect and lock onto the reference bit and then to detect the phase reversed start bit. The microprocessor then positions its internal timing so as to take samples of the coded word at the midpoints of the successive bit periods and to perform frequency comparison operations to detect phase reversals or lack of phase reversals and thereby determine the logic values of the other bits. The processing performed by the microprocessor tolerates slight frequency shifts and skewing of data.