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Method and apparatus for differential global positioning system (DGPS)-based real time attitude determination (RTAD)

  • US 9,829,582 B2
  • Filed: 09/19/2011
  • Issued: 11/28/2017
  • Est. Priority Date: 09/19/2011
  • Status: Active Grant
First Claim
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1. A differential global positioning system (DGPS) processor, comprising:

  • an almost fixed integer ambiguity (AFIA) module configured to generate, in real-time, a multiple dimensional state vector of integer ambiguities and multiple dimensional corrections using double difference (DD) measurements for pseudo-range (PR) and carrier phase (CP) pairs generated from at least three global positioning system (GPS) receivers, wherein, to generate the multiple dimensional state vector, the AFIA module is operative to (i) determine a difference between a double difference (DD) measurement error and a DD measurement vector for a defined number of GPS satellites in view and at least three GPS receivers, and (ii) divide the difference by an observation matrix for the PR and CP pairs, wherein the AFIA module is stored in a digital memory device or is implemented in a hardware circuit;

    an attitude module configured to generate an attitude from the multiple dimensional state vector of integer ambiguities and multiple dimensional corrections, wherein the attitude module is stored in a digital memory device or is implemented in a hardware circuit;

    a single difference (SD) module configured to generate at least two single difference observables, wherein a single difference observable is the difference between two receiver observables, wherein a receiver observable includes observable GPS data or a LOS unit vector for each receiver, wherein the SD module is stored in a digital memory device or is implemented in a hardware circuit; and

    a DD module configured to generate at least two double difference observables, wherein a double difference observable is the difference between SD observables of two GPS satellites, wherein the DD module is stored in a digital memory device or is implemented in a hardware circuit,wherein a number of single difference observables or a number of double difference observables is less than a number of GPS receivers used to generate observable GPS data.

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