Patent Number: 6,297,770

Title: Global positioning system and global positioning method with improved sensitivity by detecting navigation data inversion boundaries

Abstract: A Global Positioning System (GPS) forms a C/A code sequence by summing, beginning from a polarity inversion boundary determined by a correlation peak position detector, chips at corresponding positions in PN frames constituting each bit of navigation data; calculates pseudo ranges by computing correlation between the C/A code sequence and a reference C/A code sequence generated by the GPS terminal; and determines the position of the GPS terminal using the pseudo ranges and navigation data. The navigation data detected inside the GPS terminal is used when a received electric field detected by a received electric field intensity detector is greater than a threshold level, and the navigation data received from an external system is used when the received electric field is below the threshold level. Thus, the number of PN frames to be integrated is limited because the polarity inversion boundaries of the navigation data are detected, and hence the sensitivity (S/N ratio) is sufficient. Communication between a terminal and a base station is not always required for determining the position because the GPS terminal does not always obtain the Doppler information from the base station, reducing communication cost.

Inventors: Ueda; Fumio (Tokyo, JP), Hirata; Seiichiro (Tokyo, JP)

Assignee: Mitsubishi Denki Kabushiki Kaisha

International Classification: G01S 1/00 (20060101); H04B 007/185 ()

Expiration Date: 10/02/2018