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. 28, 1998
Filed:
Sep. 20, 1996
Applicant:
Inventors:
James Robert Jensen, Columbia, MD (US);
Robert Steven Bokulic, Columbia, MD (US);
Assignee:
The Johns Hopkins University, Baltimore, MD (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01S / ;
U.S. Cl.
CPC ...
342104 ; 342115 ; 342 50 ; 342 46 ;
Abstract
A method and apparatus are disclosed for making precise velocity measurements of a spacecraft using a two-way noncoherent Doppler tracking system. By comparing the received uplink and transmitted downlink frequencies on-board the spacecraft, information is generated that is included in the downlink signal and used to cancel spacecraft oscillator drift rate effects in the two-way Doppler measurement made by the ground station. This data can also be used to characterize the drift rate of the spacecraft oscillator, thus permitting periods of accurate one-way Doppler tracking by the ground station.