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. 26, 1993
Filed:
Feb. 10, 1989
Lawrence W Hill, Arlington, MA (US);
Frederick W Sarles, Lexington, MA (US);
ComSource Systems Corporation, Hollis, NH (US);
Abstract
A system for digital communication over a wire lain along the path of guided vehicles to a modem and a loop driver, the modem providing high frequency signals and the loop driver providing low frequency control signals. Instead, the modem and the loop driver are connected to one end of the wire and the other end of the wire is connected through an impedance matching network to earth ground. The impedance matching network provides an impedance approximately equal to the impedance of the wire at the frequency of the high frequency signals. The impedance matching network may conveniently comprise an inductor (choke) in parallel with a capacitor connected between the end of the wire and earth ground and a plurality of resistors connected in parallel with said inductor and capacitor. The resistors are selectively clipped to eliminate the echo bringing the impedance of the impedance matching network to approximate equality with the impedance of the wire at the frequency of the high frequency signals. Alternatively, a single loop connected in the ordinary way to the modem and loop driver, may be cut to form two separate wires and two separate impedance networks provided one at each end of the wires to earth ground.