Frequency diversity receiving system based on cancellation of C/A code in GPS

• US 5,093,839 A
• Filed: 01/02/1991
• Issued: 03/03/1992
• Est. Priority Date: 09/06/1990
• Status: Expired due to Term

• Current Assignee: Sokkisha Company Limited
• Original Assignee: Sokkisha Company Limited
• Inventors: Wang, Hefeng, Kohno, Ryuji, Imai, Hideki
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): CAIN, DAVID C
• Application Number:
  US07/636,789
• Time in Patent Office: 426 Days
• Field of Search: 375/1, 380/8, 342/357
• US Class Current: 375/148
• CPC Class Codes: G01S 19/32 Multimode operation in a single same satellite system, e.g. GPS L1/L2
• CPC Class Codes: H04B 7/12 Frequency diversity

Abstract

A frequency diversity receiving system is based on cancellation of a C/A (Clear/Acquisition) code in a GPS (Global Positioning System). Spread spectrum signals of a P code (Precision) code is picked up by removing, in an interference removal circuit, spread spectrum signals of the C/A code out of spread spectrum signals of L₁ band which are transmitted from GPS satellites. A difference in relative delay times between the spread spectrum signals of the P code in L₁ band and spread spectrum signals of the P code in L₂ band, which are also transmitted from GPS satellites, is obtained in a modified DLL (Delay Locked Loop).

Claims

1. A frequency diversity receiving system based on cancellation of a C/A code in a GPS comprising the steps of:

picking up spread spectrum signals of a P code by removing spread spectrum signals of said C/A code out of spread spectrum signals of L₁ band, said spread spectrum signals of L₁ band being transmitted from GPS satellites; and

obtaining a difference in relative delay times between said spread spectrum signals of said P code in L₁ band and spread spectrum signals of said P code in L₂ band, said signals of said P code in L₂ band being transmitted from said GPS satellites.

2. A frequency diversity receiving system based on cancellation of a C/A code in a GPS as claimed in claim 1, wherein said spread spectrum signals of said C/A code are removed in an interference removal circuit.

3. A frequency diversity receiving system based on cancellation of a C/A code in a GPS as claimed in claim 2, wherein said difference in relative delay times is obtained in a modified DLL circuit.