Code multipath analyzer using weighted or modified correlations

• US 6,130,908 A
• Filed: 10/31/1997
• Issued: 10/10/2000
• Est. Priority Date: 10/31/1997
• Status: Expired due to Term

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Pon, Rayman W.
• Primary Examiner(s): Ghebretinsae, Temesghen
• Assistant Examiner(s): BURD, KEVIN MICHAEL
• Application Number:
  US08/962,337
• Time in Patent Office: 1,075 Days
• Field of Search: 375/346, 375/227, 375/208, 370/209
• US Class Current: 375/227
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: H04B 1/709 Correlator structure
• CPC Class Codes: H04B 1/711 the interference being multi-path interference
• CPC Class Codes: H04B 1/712 Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
• CPC Class Codes: H04B 2001/70706 using a code tracking loop, e.g. a delay locked loop

Abstract

The apparatus and the method for analyzing the code multipath satellite disturbance are disclosed. The apparatus includes the tracking channel and the analyzing circuit. The tracking channel can include the weighted or modified weighting functions to decrease the level of the multipath reference signal. The analyzing circuit can include a plurality of additional correlator circuits used to build the filter function that is utilized to analyze the incoming code multipath disturbance.

Claims

1. An apparatus for analyzing a composite signal, wherein said composite signal includes a direct signal transmitted from at least one satellite and an incoming code multipath distortion component;

said apparatus comprising;

a satellite code channel tracking circuit configured to receive said composite signal;

wherein said satellite code channel tracking circuit is configured to generate a satellite code tracking function having a tracking code multipath distortion component;

wherein said satellite code channel tracking circuit further comprises;

at least two partial code tracking circuits, wherein each said partial tracking circuit is used to minimize said tracking code multipath distortion component;

wherein said minimized tracking code multipath distortion component comprises a residual tracking code multipath distortion component; and

at least one additional estimation tracking circuit;

wherein each said additional estimation circuit is used to estimate and further minimize said residual tracking code multipath distortion component; and

an analyzing circuit connected to said satellite code channel tracking circuit; and

wherein said analyzing circuit is configured to analyze said residual tracking code multipath distortion component.

2. The apparatus of claim 1;

wherein at least one said partial code tracking circuits further comprises;

a Weight tracking circuit configured to provide a satellite code tracking function having a code multipath response envelope;

wherein said Weight tracking circuit is configured to generate a Weight function at a level selected from the group consisting of {an Input level, a Local Carrier reference level, a Complex Mixer circuit level, a Local Code reference level, and a Code Correlation circuit level}.

3. The apparatus of claim 1;

wherein at least one said partial code tracking circuit further comprises;

a Modify tracking circuit configured to provide a satellite code tracking function having a code multipath response envelope;

wherein said Modify tracking circuit is configured to generate a Modify function at a level selected from the group consisting of {an Input level, a Local Carrier reference level, a Complex Mixer circuit level, a Local Code reference level, and a Code Correlation circuit level}.

4. The apparatus of claim 2;

wherein said Weight tracking circuit further comprises;

an (I &

Q) Input Weight tracking circuit configured to process said input composite signal from said satellite and to generate an (I &

Q) weighted component of an (I &

Q) input composite signal.

5. The apparatus of claim 3;

wherein said Modify tracking circuit further comprises;

an (I &

Q) Input Modify tracking circuit configured to process said input composite signal from said satellite and to generate an (I &

Q) modified component of an (I &

Q) input composite signal.

6. The apparatus of claim 2;

wherein said Weight tracking circuit further comprises;

an (I &

Q) Weight Local Carrier reference circuit configured to generate an (I &

Q) weighted component of an (I &

Q) local carrier reference signal.

7. The apparatus of claim 3;

wherein said Modify tracking circuit further comprises;

an (I &

Q) Modify Local Carrier reference circuit configured to generate an (I &

Q) modified component of an (I &

Q) local carrier reference signal.

8. The apparatus of claim 2;

wherein said Weight tracking circuit further comprises;

an Inphase Channel Weight Complex Mixer circuit configured to generate an (I) weighted component of a baseband sampled composite signal.

9. The apparatus of claim 3;

wherein said Modify tracking circuit further comprises;

an Inphase Channel Modify Complex Mixer circuit configured to generate an (I) modified component of a baseband sampled composite signal.

10. The apparatus of claim 2;

wherein said Weight tracking satellite channel circuit further comprises;

a Weight Local Code reference circuit configured to locally generate a Local code weighted reference signal.

11. The apparatus of claim 3;

wherein said Modify tracking satellite channel circuit further comprises;

a Modify Local Code reference circuit configured to locally generate a Local code modified reference signal.

12. The apparatus of claim 2;

wherein said Weight tracking satellite channel circuit further comprises;

a Weight Code Correlation circuit configured to generate a weighted correlation component of a composite correlation signal.

13. The apparatus of claim 3;

wherein said Modify tracking satellite channel circuit further comprises;

a Modify Code Correlation circuit configured to generate a modified correlation component of a composite correlation signal.

14. The apparatus of claim 1;

wherein said additional estimation circuit further comprises;

a Weight estimation circuit configured to estimate and further minimize said residual code multipath response component, wherein said Weight estimation circuit is configured to generate a Weight function at a level selected from the group consisting of {an Input level, a Local Carrier reference level, a Complex Mixer circuit level, a Local Code reference level, and a Code Correlation circuit level}.

15. The apparatus of claim 1;

wherein said additional estimation circuit further comprises;

a Modify estimation circuit configured to estimate and further minimize said residual code multipath response component, wherein said Modify estimation circuit is configured to generate a Modify function at a level selected from the group consisting of {an Input level, a Local Carrier reference level, a Complex Mixer circuit level, a Local Code reference level, and a Code Correlation circuit level}.

16. The apparatus of claim 14;

wherein said Weight estimation circuit further comprises;

an (I &

Q) Input Weight estimation circuit configured to generate an (I &

Q) weighted estimation component of said (I &

Q) input composite signal.

17. The apparatus of claim 15;

wherein said Modify estimation circuit further comprises;

an (I &

Q) Input Modify estimation circuit configured to generate an (I &

Q) modified estimation component of said (I &

Q) input composite signal.

18. The apparatus of claim 14;

wherein said Weight estimation circuit further comprises;

an (I &

Q) Weight Local Carrier reference estimation circuit configured to generate an (I &

Q) weighted estimation component of an (I &

Q) local carrier reference signal.

19. The apparatus of claim 15;

wherein said Modify estimation circuit further comprises;

an (I &

Q) Modify Local Carrier reference estimation circuit configured to generate an (I &

Q) modified estimation component of an (I &

Q) local carrier reference signal.

20. The apparatus of claim 14;

wherein said Weight estimation circuit further comprises;

an Inphase Channel Weight Complex Mixer estimation circuit configured to generate an (I) weighted estimation component of a baseband sampled composite signal.

21. The apparatus of claim 15;

wherein said Modify estimation tracking circuit further comprises;

an Inphase Channel Modify Complex Mixer estimation circuit configured to generate an (I) modified estimation component of a baseband sampled composite signal.

22. The apparatus of claim 14;

wherein said Weight estimation satellite channel circuit further comprises;

a Weight Local Code reference estimation circuit configured to locally generate a Local code weighted estimation reference signal.

23. The apparatus of claim 15;

wherein said Modify estimation satellite channel circuit further comprises;

a Modify Local Code estimation reference circuit configured to locally generate a Local code modified estimation reference signal.

24. The apparatus of claim 14;

wherein said Weight estimation satellite channel circuit further comprises;

a Weight Code Correlation estimation circuit configured to generate a weighted correlation estimation component of a composite correlation signal.

25. The apparatus of claim 15;

wherein said Modify estimation satellite channel circuit further comprises;

a Modify Code Correlation estimation circuit configured to generate a modified correlation estimation component of a composite correlation signal.

26. The apparatus of claim 1;

wherein said analyzing circuit further comprises;

a plurality of N analyzing circuits, N being an integer; and

wherein said incoming code multipath distortion component comprises N portions of said incoming code multipath distortion component.

27. A apparatus for analyzing a composite signal, wherein said composite signal includes a direct signal transmitted from at least one satellite and at least N portions of said incoming code multipath distortion component;

N being an integer;

said apparatus comprising;

a satellite code channel broad correlator tracking circuit configured to receive said composite signal;

wherein said satellite code channel broad correlator tracking circuit further comprises;

a code NCO &

Generator block configured to generate a local code signal;

an Early (E) flip-flop connected to said code NCO &

Generator block, wherein said E flip-flop is configured to generate an Early (E) signal;

a Punctual (P) flip-flop connected to said E flip-flop, wherein said P flip-flop is configured to generate a Punctual (P) signal; and

a Late (L) flip-flop connected to said P flip-flop, wherein said L flip-flop is configured to generate a Late (L) signal; and

a plurality of N analyzing circuits, N being an integer; and

wherein said plurality of N analyzing circuits further comprises;

(N+2) serially connected additional flip-flops;

wherein a first additional flip-flop comprises an A flip-flop connected to said E flip-flop, and wherein said A flip-flop is configured to generate an A additional correlation reference signal (Addl Corr A);

wherein a second additional flip-flop comprises a B flip-flop connected to said A flip-flop, wherein said B flip-flop is configured to generate a B additional correlation reference signal (Addl Corr B);

wherein a third additional flip-flop comprises a C flip-flop connected to said B flip-flop, wherein said C flip-flop is configured to generate a C additional correlation reference signal (Addl Corr C);

wherein a fourth additional flip-flop comprises a D flip-flop connected to said C flip-flop, wherein said D flip-flop is configured to generate a D additional correlation reference signal (Addl Corr D);

wherein an l-th additional flip-flop is connected to an (l-1)-th flip-flop and is connected to an (l+1)-th flip-flop, and wherein said l-th flip-flop is configured to generate an l-th additional correlation reference signal (Addl Corr l);

l being an integer greater than 4 and less than (N+2);

and wherein an (N+2)-th additional flip-flop is connected to a (N+1)-th flip-flop, wherein said (N+2)-th flip-flop is configured to generate an (N+2)-th additional correlation signal (Addl Corr (N+2));

and wherein said (Addl Corr A) signal, said (Addl Corr B) signal, and said (Addl Corr C) signal are used by a computer to form a first additional weighted correlation function W₁ * that is utilized to analyze a first portion of said incoming code multipath distortion signal;

and wherein said (Addl Corr B) signal, said (Addl Corr C) signal, and said (Addl Corr D) signal are used by said computer to form a second additional weighted correlation function W₂ * that is utilized to analyze a second portion of said incoming code multipath distortion signal;

and wherein said (Addl Corr l) signal, said (Addl Corr (l+1)) signal, and said (Addl Corr (l+2)) signal are used by said computer to form an l-th additional weighted correlation function W₁ * that is utilized to analyze an l-th portion of said incoming code multipath distortion signal;

and wherein said (Addl Corr N) signal, said (Addl Corr (N+1)) signal, and said (Addl Corr N+2)) signal are used by said computer to form an N-th additional weighted correlation function W_N * that is utilized to analyze an N-th portion of said incoming code multipath distortion signal.

28. An apparatus for analyzing a composite signal, wherein said composite signal includes a direct signal transmitted from at least one satellite and at least N portions of said incoming code multipath distortion component;

N being an integer;

said apparatus comprising;

a satellite code channel broad correlator tracking circuit configured to receive said composite signal;

wherein said satellite code channel broad correlator tracking circuit further comprises;

a code NCO &

Generator block configured to generate a local code signal;

an Early (E) flip-flop connected to said code NCO &

Generator block, wherein said E flip-flop is configured to generate an Early (E) signal;

a Punctual (P) flip-flop connected to said E flip-flop, wherein said P flip-flop is configured to generate a Punctual (P) signal; and

a Late (L) flip-flop connected to said P flip-flop, wherein said L flip-flop is configured to generate a Late (L) signal; and

a plurality of N analyzing circuits, N being an integer; and

wherein said plurality of N analyzing circuits further comprises;

an (N+2) serially connected additional flip-flops; and

an N dedicated hardware circuits;

wherein a first additional flip-flop comprises an A flip-flop connected to said E flip-flop, and wherein said A flip-flop is configured to generate an A additional correlation reference signal (Addl Corr A);

wherein a second additional flip-flop comprises a B flip-flop connected to said A flip-flop, wherein said B flip-flop is configured to generate a B additional correlation reference signal (Addl Corr B);

wherein a third additional flip-flop comprises a C flip-flop connected to said B flip-flop, wherein said C flip-flop is configured to generate a C additional correlation reference signal (Addl Corr C);

wherein a fourth additional flip-flop comprises a D flip-flop connected to said C flip-flop, wherein said D flip-flop is configured to generate a D additional correlation reference signal (Addl Corr D);

wherein an l-th additional flip-flop is connected to an (l-1)-th flip-flop and connected to an (l+1)-th flip-flop, wherein said l-th flip-flop is configured to generate an l-th additional correlation reference signal (Addl Corr l);

l being an integer greater than 4 and less than (N+2);

and wherein an (N+2)-th additional flip-flop is connected to an (N+1)-th flip-flop, wherein said (N+2)-th flip-flop is configured to generate an (N+2)-th additional correlation reference signal (Addl Corr (N+2));

and wherein said (Addl Corr A) signal, said (Addl Corr B) signal, and said (Addl Corr C) signal are used by a first dedicated hardware circuit to form a first additional weighted correlation function W₁ * that is utilized to analyze a first portion of said incoming code multipath distortion signal;

and wherein said (Addl Corr B) signal, said (Addl Corr C) signal, and said (Addl Corr D) signal are used by a second dedicated hardware circuit computer to form a second additional weighted correlation function W₂ * that is utilized to analyze a second portion of said incoming code multipath distortion signal;

and wherein said (Addl Corr l) signal, said (Addl Corr (l+1)) signal, and said (Addl Corr (l+2)) signal are used by an l-th dedicated hardware circuit computer to form an l-th additional weighted correlation function W₁ * that is utilized to analyze an l-th portion of said incoming code multipath distortion signal;

and wherein said (Addl Corr N) signal, said (Addl Corr (N+1)) signal, and said (Addl Corr (N+2)) signal are used by an N-th dedicated hardware circuit to form an N-th additional weighted correlation function W_N * that is utilized to analyze an N-th portion of said incoming code multipath distortion signal.