Time delay and distance measurement

US7982861B2 · kind B2 · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• James B. Abshire · Laurel, US
• Xiaoli Sun · Shandong, CN

Key dates

• Filing date: Jul 31, 2008
• Grant date: Jul 19, 2011
• Expiry date: Sep 11, 2029

Classification

• Technology area (CPC G): Physics
• CPC primary: G01S17/10
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method for measuring time delay and distance may include providing an electromagnetic radiation carrier frequency and modulating one or more of amplitude, phase, frequency, polarization, and pointing angle of the carrier frequency with a return to zero (RZ) pseudo random noise (PN) code. The RZ PN code may have a constant bit period and a pulse duration that is less than the bit period. A receiver may detect the electromagnetic radiation and calculate the scattering profile versus time (or range) by computing a cross correlation function between the recorded received signal and a three-state RZ PN code kernel in the receiver. The method also may be used for pulse delay time (i.e., PPM) communications.