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:
Apr. 12, 1994
Filed:
Jan. 06, 1993
Dale D Fonnesbeck, Kaysville, UT (US);
Vaughn L Mower, Bountiful, UT (US);
Unisys Corporation, Blue Bell, PA (US);
Abstract
The present invention applies in a communication system where - a) two vehicles V.sub.A and V.sub.B transmit data to each other intermittently, b) data transmitted from V.sub.A to V.sub.B is modulated in V.sub.A by a PN code PN.sub.1 having a time varying phase .phi..sub.MA and is correlated in V.sub.B by the code PN.sub.1 having a different time varying phase .phi..sub.CB, and c) data transmitted from V.sub.B to V.sub.A is modulated in V.sub.B by a PN code PN.sub.2 having a time varying phase .phi..sub.MB and is correlated in V.sub.A by the code PN.sub.2 having a different time varying phase .phi..sub.CA. With the present invention, the codes PN.sub.1 and PN.sub.2 can have respective nominal frequencies f.sub.1 =1/T.sub.1 and f.sub.2 =1/T.sub.2 that drift in at least one of the vehicles. This drift, is then compensated for by the present invention by sensing, during the data transmissions, the phase shifts .DELTA..phi..sub.MA, .DELTA..phi..sub.MB and .DELTA..phi..sub.CB which respectively occur in said PN codes over a time interval .DELTA.T.sub.X ; calculating a drift rate DR from the sensed phase shifts; measuring a time interval .DELTA.T.sub.Y during which data transmission between V.sub.A and V.sub.B are stopped; and thereafter, compensating for drift before re-establishing data transmissions by phase shifting, in one of the vehicles, code PN.sub.1 by an amount proportional to (DR) (.DELTA.T.sub.Y).