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:
Nov. 13, 2001
Filed:
May. 25, 2000
Alain Renard, Chabeuil, FR;
Marc Revol, Cachan, FR;
Thomson-CSF Sextant, Velizy Villacoublay, FR;
Abstract
A method for position determination with the aid of GPS satellites, including reception processing of a GPS satellite signal L2 modulated by an encrypted code Y having a key not available from the GPS satellite, so as to assess a delay of the signal L2 with respect to the signal L1 and to deduce therefrom the magnitude of the ionospheric effect so as to take account thereof and improve the accuracy of the location finding. This processing includes reducing the signal L2 to a lower band and in despreading the signal L2 by means of the non-encrypted code P produced locally in reception by a local generator of a non-encrypted spreading code P synchronized with the code Y (encrypted P) transmitted, with the aid of a phase lock loop with three parallel paths: a first path demodulated by a precise version of the locally produced non-encrypted spreading code P, a second advanced path demodulated a first time by an advanced version of the locally produced non-encrypted spreading code P and a second time by the demodulated signal of the precise path, and a third delayed path demodulated a first time by a delayed version of the locally produced non-encrypted spreading code P and a second time by the demodulated signal of the precise path, synchronization being achieved by searching for an equality of power of the carrier of the signal L2 at the output of the advanced and delayed paths.