Spread spectrum receiver using a pseudo-random noise code for ranging applications in a way that reduces errors when a multipath signal is present

• US 6,463,091 B1
• Filed: 05/23/2000
• Issued: 10/08/2002
• Est. Priority Date: 08/09/1995
• Status: Expired due to Term

• Current Assignee: MiTAC International Corporation (MiTAC Holdings Corp.)
• Original Assignee: Magellan Corporation (Thales SA)
• Inventors: Zhodzicshsky, Mark, Veitsel, Victor, Sila-Novatisky, Stanislov, Ashjaee, Javad, Garin, Lionel
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US09/577,023
• Time in Patent Office: 868 Days
• Field of Search: 375/147, 375/150, 375/148, 375/149, 375/347, 375/267, 375/343, 375/326, 455/132, 342/357.12, 701/213-215
• US Class Current: 375/149
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/709 Correlator structure
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers

Abstract

A receiver of a radio frequency signal having a pseudo-random noise (PRN) code, and techniques of processing such a signal that are especially adapted for ranging applications. A signal corresponding to the PRN code is locally generated and used for decoding the received signal in a manner to reduce ranging errors that can result when multipath (delayed) versions of the radio frequency signal are also present. A significant application of the receiver and signal processing techniques of the present invention is in a Global Positioning System (GPS), wherein a number of such signals from several satellites are simultaneously received and processed in order to obtain information of the position, movement, or the like, of the receiver. A delay locked loop (DLL) correlator, provided in each of the receiver'"'"'s multiple processing channels, locks onto a line of sight signal from one of the satellites with the effect of any multipath signal(s) being significantly reduced.

Claims

1. A method of reducing errors in a received signal, comprising:

locking one or more delay locked loop correlators onto a combination of line-of-sight and multipath signals;

providing a loop gain in the central region of said combination of line-of-sight and multipath signals, whereby said correlators discriminate against said multipath signals by producing a plurality of zero segments separated by operating segments in an error signal wherein only line-of-sight or multipath signals of said combination that have a relative phase within said operating segments affect said locking, if a receiver is not in a start-up mode; and

providing a loop gain in the central region of said combination of line-of-sight and multipath signals, whereby said correlators do not discriminate against said multipath signals by producing a plurality of zero segments separated by operating segments in an error signal wherein only line-of-sight or multipath signals of said combination that have a relative phase within said operating segments affect said locking, if a receiver is in said start-up mode.

2. A computer program product comprising:

a computer usable medium having computer readable program code embodied therein configured to reduce errors in a received signal, said computer program product comprising;

computer readable code configured to cause a computer to lock one or more delay locked loop correlators onto a combination of line-of-sight and multipath signals;

computer readable code configured to cause a computer to provide a loop gain in the central region of said combination of line-of-sight and multipath signals, whereby said correlators discriminate against said multipath signals by producing a plurality of zero segments separated by operating segments in an error signal wherein only line-of-sight or multipath signals of said combination that have a relative phase within said operating segments affect said locking, if a receiver is not in a start-up mode; and

computer readable code configured to cause a computer to provide a loop gain in the central region of said combination of line-of-sight and multipath signals, whereby said correlators do not discriminate against said multipath signals by producing a plurality of zero segments separated by operating segments in an error signal wherein only line-of-sight or multipath signals of said combination that have a relative phase within said operating segments affect said locking, if a receiver is in said start-up mode.

3. A receiver configured to reduce errors in a received signal, comprising:

one or more delay locked loop correlators, said correlators configured to lock onto a combination of line-of-sight and multipath signals; and

signal processors providing a loop gain in the central region of said combination of line-of-sight and multipath signals so that said correlators discriminate against said multipath signals by producing a plurality of zero segments separated by operating segments in an error signal wherein only line-of-sight or multipath signals of said combination that have a relative phase within said operating segments affect said locking, if a receiver is not in a start-up mode;

said signal processors also providing a loop gain in the central region of said combination of line-of-sight and multipath signals, whereby said correlators do not discriminate against said multipath signals by producing a plurality of zero segments separated by operating segments in an error signal wherein only line-of-sight or multipath signals of said combination that have a relative phase within said operating segments affect said locking, if a receiver is in said start-up mode.

4. A system for reducing errors in a received signal, comprising:

one or more delay locked loop correlators, said correlators configured to lock onto a combination of line-of-sight and multipath signals;

signal processors providing a loop gain in the central region of said combination of line-of-sight and multipath signals so that said correlators discriminate against said multipath signals by producing a plurality of zero segments separated by operating segments in an error signal wherein only line-of-sight or multipath signals of said combination that have a relative phase within said operating segments affect said locking, if a receiver is not in a start-up mode;

said signal processors also providing a loop gain in the central region of said combination of line-of-sight and multipath signals, whereby said correlators do not discriminate against said multipath signals by producing a plurality of zero segments separated by operating segments in an error signal wherein only line-of-sight or multipath signals of said combination that have a relative phase within said operating segments affect said locking, if a receiver is in said start-up