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:
May. 05, 2009
Filed:
May. 01, 2007
Nobuhiro Kishimoto, Osaka, JP;
Seiichiro Hirata, Nagaokakyo-shi, Kyoto, JP;
Nobuhiro Kishimoto, Osaka, JP;
Seiichiro Hirata, Nagaokakyo-shi, Kyoto, JP;
Other;
Abstract
A receiver terminal receives a frequency from an external reference oscillator portion, which is more accurate than that of a frequency generated within the receiver in a local oscillator portion. The frequency from the local oscillator portion is measured using the external frequency as the reference, which determines the error in the local oscillator frequency relative to the external reference and permits the local oscillator frequency to be corrected to within the error of the external oscillator frequency. A plurality of candidate values for the remaining local frequency error are selected within a predetermined frequency range to include any remaining error of the local oscillator frequency. The received signal from a satellite is correlated with a matching pseudorandom code to detect the signal and measure the signal delay and Doppler shift of the signal relative to the corrected local oscillator frequency. The delay value is used to obtain a pseudorange measurement and the measured Doppler shift permits further correction to the local oscillator frequency, thus reducing the frequency search range for the remaining satellites.