Code multipath estimation for weighted or modified tracking using weighted or modified correlations

• US 5,917,866 A
• Filed: 04/04/1997
• Issued: 06/29/1999
• Est. Priority Date: 04/04/1997
• 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): Pham, Chi H.
• Assistant Examiner(s): Bayard, Emmanuel
• Application Number:
  US08/833,183
• Time in Patent Office: 816 Days
• Field of Search: 375/206, 375/267, 375/285, 375/346, 375/347, 455/12.1, 455/63, 455/65, 455/137, 455/139, 455/276.1, 455/303, 455/304, 455/427, 455/506
• US Class Current: 375/346
• 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

Abstract

The apparatus and method for estimation and minimization of the residual multipath error signal are disclosed. The reduction of the multipath error signal is achieved by using the weighted or modified tracking. The estimation and minimization of the reduced multipath error signals is achieved by using the generator of additional modified or weighted signals.

Claims

1. An apparatus for use in decoding a composite signal, wherein said composite signal includes a direct signal transmitted from at least one communication satellite and a multipath distortion component;

said apparatus comprising;

a satellite channel code receiving circuit configured to generate a satellite code receiving function having a residual multipath error response envelope;

and

at least one additional circuit connected to said satellite channel code receiving circuit;

wherein at least one said additional circuit further comprises;

a weighted code estimation circuit configured to estimate and eliminate said code residual multipath distortion component;

wherein said weighted code estimation circuit further comprises;

a code NCO &

Generator configured to generate a local code signal;

a C flip-flop connected to said code NCO &

Generator, wherein said C flip-flop is configured to generate a C signal;

a D flip-flop connected to said C flip-flop, wherein said D flip-flop is configured to generate a D signal;

an F flip-flop connected to said D flip-flop, wherein said F flip-flop is configured to generate an F signal;

a first EX-OR gate connected to said C flip-flop and connected to said D flip-flop, wherein said first EX-OR gate is configured to generate an enabling (A) additional signal; and

a second EX-OR gate connected to said D flip-flop and connected to said F flip-flop, wherein said second EX-OR gate is configured to generate an enabling (B) additional signal.

2. An apparatus for use in decoding a composite signal, wherein said composite signal includes a direct signal transmitted from at least one communication satellite and a multipath distortion component;

said apparatus comprising;

a satellite channel code receiving circuit configured to generate a satellite code receiving function having a residual multipath error response envelope;

and

at least one additional circuit connected to said satellite channel code receiving circuit;

wherein at least one said additional circuit further comprises;

a weighted code estimation circuit configured to estimate and eliminate said code residual multipath distortion component;

wherein said weighted code estimation circuit further comprises;

a code NCO &

Generator configured to generate a local code signal;

a C flip-flop connected to said code NCO &

Generator, wherein said C flip-flop is configured to generate a C signal;

a D flip-flop connected to said C flip-flop, wherein said D flip-flop is configured to generate a D signal;

an F flip-flop connected to said D flip-flop, wherein said F flip-flop is configured to generate an F signal;

a G flip-flop connected to said F flip-flop, wherein said G flip-flop is configured to generate a G signal;

a first EX-OR gate connected to said C flip-flop and connected to said F flip-flop, wherein said first EX-OR gate is configured to generate an enabling (A) additional signal; and

a second EX-OR gate connected to said F flip-flop and connected to said G flip-flop, wherein said second EX-OR gate is configured to generate an enabling (B) additional signal.

3. An apparatus for use in decoding a composite signal, wherein said composite signal includes a direct signal transmitted from at least one communication satellite and a multipath distortion component;

said apparatus comprising;

a satellite channel code receiving circuit configured to generate a satellite code receiving function having a residual multipath error response envelope;

and

at least one additional circuit connected to said satellite channel code receiving circuit;

wherein at least one said additional circuit further comprises;

a modified code estimation circuit configured to estimate and eliminate said code residual multipath distortion component;

wherein said modified code estimation circuit further comprises;

a code NCO &

Generator configured to generate a local code signal;

an G flip-flop connected to said code NCO &

Generator, wherein said G flip-flop is configured to generate an G signal;

a H flip-flop connected to said G flip-flop, wherein said H flip-flop is configured to generate a H signal;

an Early flip-flop connected to said H flip-flop, wherein said Early flip-flop is configured to generate an Early signal;

a Punctual flip-flop connected to said Early flip-flop, wherein said Punctual flip-flop is configured to generate a Punctual signal;

a Late flip-flop connected to said Punctual flip-flop, wherein said Late flip-flop is configured to generate a Late signal;

an EX-OR gate connected to said A flip-flop and connected to said B flip-flop;

an X flip-flop connected to said EX-OR gate, wherein said X flip-flop is configured to generate an X signal;

a Y flip-flop connected to said X flip-flop, wherein said Y flip-flop is configured to generate a Y signal;

an K flip-flop connected to said code NCO &

Generator, wherein said K flip-flop is configured to generate an K signal;

an M flip-flop connected to said K flip-flop, wherein said M flip-flop is configured to generate an M signal;

a Z flip-flop connected to said M flip-flop, wherein said Z flip-flop is configured to generate a Z signal;

a W flip-flop connected to said Z flip-flop, wherein said W flip-flop is configured to generate a W signal;

a first AND gate connected to said Y flip-flop and connected to said W flip-flop, wherein said first AND gate is configured to generate an enabling (A) additional signal; and

a second AND gate connected to said Y flip-flop and connected to said Z flip-flop, wherein said second AND gate is configured to generate an enabling (B) additional signal.

4. An apparatus for use in decoding a composite signal, wherein said composite signal includes a direct signal transmitted from at least one communication satellite and a multipath distortion component;

said apparatus comprising;

a satellite channel code receiving circuit configured to generate a satellite code receiving function having a residual multipath error response envelope;

and

at least one additional circuit connected to said satellite channel code receiving circuit;

wherein at least one said additional circuit further comprises;

a modified code estimation circuit configured to estimate and eliminate said code residual multipath distortion component;

wherein said modified code estimation circuit further comprises;

a code NCO &

Generator configured to generate a local code signal;

an G flip-flop connected to said code NCO &

Generator, wherein said G flip-flop is configured to generate an G signal;

a H flip-flop connected to said G flip-flop, wherein said H flip-flop is configured to generate an H signal;

an Early flip-flop connected to said H flip-flop, wherein said Early flip-flop is configured to generate an Early signal;

a Punctual flip-flop connected to said Early flip-flop, wherein said Punctual flip-flop is configured to generate a Punctual signal;

a Late flip-flop connected to said Punctual flip-flop, wherein said Late flip-flop is configured to generate a Late signal;

an EX-OR gate connected to said A flip-flop and connected to said B flip-flop;

an X flip-flop connected to said EX-OR, wherein said X flip-flop is configured to generate an X signal;

a Y flip-flop connected to said X flip-flop, wherein said Y flip-flop is configured to generate a Y signal;

an K flip-flop connected to said code NCO &

Generator, wherein said K flip-flop is configured to generate an K signal;

an M flip-flop connected to said K flip-flop, wherein said M flip-flop is configured to generate an M signal;

a Z flip-flop connected to said M flip-flop, wherein said Z flip-flop is configured to generate a Z signal;

a W flip-flop connected to said Z flip-flop, wherein said W flip-flop is configured to generate a W signal;

a T flip-flop connected to said W flip-flop, wherein said T flip-flop is configured to generate a T signal;

a first AND gate connected to said Y flip-flop, connected to said T flip-flop, and connected to said W flip-flop, wherein said first AND gate is configured to generate an enabling (A) additional signal; and

a second AND gate connected to said Y flip-flop and connected to said Z flip-flop, wherein said second AND gate is configured to generate an enabling (B) additional signal.