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:
Jun. 02, 1992
Filed:
May. 20, 1991
Michael E Barnard, Reigate, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
When fewer than three of the satellites of a satellite global positioning system (GPS) such as NAVSTAR are visible to a user (15), the user cannot obtain independent positional information from the system. Since a satellite (11) in such a system is moving with respect to a user (15), its signals are received with a Doppler offset from their normal centre frequency and the frequency offset due to the satellite motion alone is calculable for a user at an approximate location from a given satellite. An additional Doppler frequency offset will result from any movement of the user. The magnitude of the additional frequency shift, in conjunction with the known speed (m) of the user, can be used to calculate the angle between the satellite motion (V.sub.1) and the user's motion and since the direction of the former is known, the user's heading from local North (N) can be calculated in instances where only one or two GPS satellites (11,12) are visible to a user.