Multi-path detection method for CDMA receivers

• US 7,702,003 B2
• Filed: 10/21/2008
• Issued: 04/20/2010
• Est. Priority Date: 12/29/2004
• Status: Active Grant

• Current Assignee: France Brevets SAS
• Original Assignee: Nokia Corporation
• Inventors: Valio, Harri, Pietila, Samuli
• Primary Examiner(s): Kim; Kevin Y
• Application Number:
  US12/288,645
• Publication Number:
  US 20090147833A1
• Time in Patent Office: 546 Days
• Field of Search: 375/142, 375/144, 375/147, 375/150
• US Class Current: 375/150
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 2201/70715 with application-specific features

Abstract

The present invention provides a method for a multi-path detection analysis and selectivity of CDMA signals using spread spectrum receivers using a correlation technique. The invention is based on determining by the spread spectrum receiver whether a distortion of a received radio frequency signal, caused by a multi-path component of said received signal, meets a predetermined condition using a pre-selected correlation analysis of said received signal. This invention is generally applicable to global navigation satellite system (GNSS) receivers and it is particularly useful in GNSS receivers, such as GPS (global positioning system) and Galileo receivers. The important goal of this invention is to provide a simple method for identifying signals that are corrupted by multi-path effects, and can be excluded from position calculation in the GNSS receivers.

Claims

1. A spread spectrum receiver, comprising:

a receiving block, configured to perform a correlation analysis of a digital signal generated from a radio frequency signal comprising a multi-path component using at least two pairs of correlation signals, each pair being symmetrical relative to a prompt point, by maintaining equal the correlation signals of one pair of said two pairs and evaluating a difference between the correlation signals of another pair of said two pairs; and

a receiver processing block, configured to detect said multi-path component and determining whether a distortion of said radio frequency signal caused by said multi-path component meets a predetermined condition using said correlation analysis of said digital signal, and for making a decision whether to further process the received radio frequency signal using results of said multi-path detection analysis for implementing a multi-path detection analysis of said radio frequency signal by said spread spectrum receiver.

2. The spread spectrum receiver of claim 1, wherein said spread spectrum receiver is configured to further process said radio frequency signal beyond said receiver processing block after making said decision, only if said distortion meets said predetermined condition, for implementing a selective function of said multi-path detection operation of the spread spectrum receiver.

3. The spread spectrum receiver of claim 1, wherein said radio frequency signal is a code division multiple access signal.

4. The spread spectrum receiver of claim 1, wherein said receiving block comprises N receiving channel blocks, N being an integer of at least a value of one, and each of said N receiving channel blocks, comprises:

residual carrier removing block, configured to generate a data intermediate signal by removing a residual carrier frequency from said digital signal using a phase-loop feedback;

code generating block, configured to generate a code signal indicative of a delay-loop feedback;

K correlator modules, wherein K is an odd integer of at least a value of five, configured to generate each of K correlation signals by a corresponding one of said K correlator modules using said data intermediate signal and K delayed code signals and for providing said K correlation signals to said receiver processing block for said determining whether a distortion of said radio frequency signal caused by said multi-path component meets a predetermined condition using a correlation analysis of said digital signal, wherein said each of said K correlation signals contains an amplitude parameter or a phase parameter or both said amplitude parameter and said phase parameter; and

K delay modules, configured to provide each of K consecutively delayed code signals to one corresponding correlator module of said K correlator modules, wherein said each of said K delayed code signals is consecutively and individually delayed by pre-selected values relative to a previously delayed code signal of said K consecutively delayed code signals starting with said code signal provided to a first delay module out of said K delay modules by said receiver processing block.

5. The spread spectrum receiver of claim 4, wherein the receiver processing block is configured to evaluate said distortion of said radio frequency signal caused by said multi-path component using said predetermined condition by comparing said amplitude parameter of an Mth correlation signal of said K correlation signals generated using an Mth delayed code signal of said K consecutively delayed code signals, wherein M=1, or 2 . . . or (K−

1)/2, and said amplitude parameter of a corresponding Lth correlation signal of said K consecutively delayed code signals generated using a corresponding Lth delayed code signal of said K correlation signals, wherein L=K, or K−

1 . . . or (K+3)/2.

6. The spread spectrum receiver of claim 4, wherein the spread spectrum receiver is configured to maintain equal, using a delay-locked loop, said amplitude parameter of two correlation signals of said K correlation signals, generated by corresponding correlator modules using corresponding delayed code signals of said K consecutively delayed code signals delayed by (K−

1)/2 and (K+3)/2 times respectively.

7. The spread spectrum receiver of claim 4, wherein the receiver processing block is configured to evaluate said distortion of said radio frequency signal caused by said multi-path component by comparing the amplitude parameter of a first of said K correlation signals generated using a first delayed code signal of said K consecutively delayed code signals and a last of said K correlation signals generated using a last delayed code signal of said K consecutively delayed code signals.

8. The spread spectrum receiver of claim 4, wherein K=5.

9. The spread spectrum receiver of claim 4, wherein the spread spectrum receiver is configured to maintain to be zero, using a delay-locked loop, said phase parameter of one correlation signal of said K correlation signals, generated by a corresponding correlator module of said K correlator modules using a corresponding delayed code signal of said K consecutively delayed code signals delayed by (K+1)/2 times and wherein phase parameters of said K correlation signals are provided to said receiver processing block for said determining.

10. The spread spectrum receiver of claim 4, wherein each said receiving channel block comprises a code generating block, configured to generate said code signal in response to a code control signal indicative of said delay-loop feedback from said receiver processing block as a part of a delay-locked loop.

11. The spread spectrum receiver of claim 4, wherein each said receiving channel block comprises a residual carrier removing block configured to generate said data intermediate signal in response to a frequency control signal indicative of said phase-loop feedback from said receiver processing block.

12. The spread spectrum receiver of claim 1, wherein said spread spectrum receiver is a global navigation satellite system receiver, a global positioning system receiver or a Galileo receiver.

13. The spread spectrum receiver of claim 1, further comprising;

an antenna, responsive to the radio frequency signal containing said multi-path component, configured to provide a radio frequency electrical signal; and

a preprocessor, responsive to the radio frequency electrical signal, configured to provide the digital signal.