System for determining position from pseudorandomly modulated radio signals

• US 5,805,200 A
• Filed: 08/11/1997
• Issued: 09/08/1998
• Est. Priority Date: 03/01/1982
• Status: Expired due to Fees

• Current Assignee: Western Atlas International Incorporated (Northrop Grumman Corporation)
• Original Assignee: Western Atlas International Incorporated (Northrop Grumman Corporation)
• Inventors: Counselman, III, Charles C.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/907,963
• Time in Patent Office: 393 Days
• Field of Search: 342/357, 342/352, 342/356, 342/424, 342/444, 342/451, 342/463, 342/156, 375/208, 375/343
• US Class Current: 342/357.26
• CPC Class Codes: G01C 15/00 Surveying instruments or accessories not provided for in groups G01C1/00 - G01C13/00
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/36 relating to the receiver frond end
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

This invention provides a method and apparatus for determining position from code modulated, suppressed carrier signals received from satellites, in which a digital composite of the signals received from a plurality of satellites is formed at a first point, the digital composite is processed to measure the carrier phase of the signal from each of the plurality of satellites to derive computer data, and said computer data are combined with data derived from measurements of signals received from the same plurality of satellites at another point, to determine position data.

Claims

1. A method for determining position from pseudorandom code modulated, suppressed carrier signals received from satellites, comprising:

forming a digital composite of said signals received from a plurality of satellites at a first point;

processing said composite to measure the carrier phase of the signal from each of said plurality of satellites, to derive computer data; and

combining said data, in order to determine position, with data derived from measurements of signals received from the same plurality of satellites at an other point.

2. The method of claim 1, wherein the position of said first point is determined with respect to the position of said other point.

3. The method of claim 1, wherein the step of combining computer data from said first point and said other point further comprises resolving integer cycle ambiguity in said computer data.

4. The method of claim 2, wherein the step of combining computer data from said first point and said other point further comprises resolving integer cycle ambiguity in said computer data.

5. The method of claim 1, further comprising:

processing said computer data to reduce errors in said position determination caused by scattering or reflections of said pseudorandom code modulated, suppressed carrier signals.

6. The method of claim 2, further comprising:

processing said computer data to reduce errors in said position determination caused by scattering or reflections of said pseudorandom code modulated, suppressed carrier signals.

7. Apparatus for determining position from pseudorandom code modulated, suppressed carrier signals received from satellites, comprising:

an analog to digital converter responsive to a composite of said signals received from a plurality of satellites at a first point, for forming a digital representation of said composite;

a digital signal processor for deriving computer data from said digital representation in response to the carrier phase of the signal from each of said plurality of satellites; and

a data processor for determining position by combining said data with data derived from signals received from the same plurality of satellites at an other point.

8. The apparatus of claim 7, wherein said data processor determines the position of said first point with respect to the position of said other point.

9. The apparatus of claim 7, wherein said digital signal processor resolves integer cycle ambiguity in said computer data.

10. The apparatus of claim 8, wherein said digital signal processor resolves integer cycle ambiguity in said computer data.

11. The apparatus of claim 7 wherein said data processor processes said computer data to reduce errors in said position determination caused by scattering or reflections of said pseudorandom code modulated, suppressed carrier signals.

12. The apparatus of claim 8 wherein said data processor processes said computer data to reduce errors in said position determination caused by scattering or reflections of said pseudorandom code modulated, suppressed carrier signals.