Multipath mitigation approach for spread spectrum ranging/positioning systems
AssigneeRockwell Collins, Inc.
InventorsBernard A. Schnaufer, Gary A. McGraw
Life of this patent
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Abstract
An apparatus and method for mitigating multipath interference in a spread spectrum ranging/positioning system receiver is disclosed. Improved peak tracking in the presence of multipath interference is accomplished with an improved discrimiriant. The discriminant may be developed from a curvilinear function based on a minimal number of correlators. Also disclosed is an open loop measurement compensation innovation that compensates for a multipath-induced shift of the correlation function peak. The positioning system receiver may have either one or both of the mitigation features.
Claims17
A method of tracking a peak of a correlation function in a positioning system receiver, comprising the steps of:
- sampling a correlation function and obtaining at least four correlation points along the correlation function;
- generating an error signal based upon a computation of a local maximum value of a curvilinear function that passes through the at least four correlation points;
- limiting the generated error signal's magnitude to a boundary value;
- and
- adjusting a receiver-generated pseudorandom noise code based on the error signal.
A positioning system receiver comprising:
- a code tracking component;
- a pseudorange measurement component determining a pseudorange measurement from correlation function signals received from said code tracking component;
- and
- a measurement compensation component removing multipath-induced bias from the pseudorange measurement determined by said pseudorange measurement components;
- wherein said code tracking component comprises a computation component sampling magnitudes of at least four correlators, and wherein said measurement compensation component removes multipath-induced bias with a multipath indicator function, the multipath indicator function containing the sampled correlator magnitudes as terms.
A method of compensating for multipath interference in a positioning system receiver comprising the steps of:
- tracking a correlation function peak by sampling at least four correlator magnitudes along the correlation function;
- determining a pseudorange measurement based on the tracked correlation function peak;
- calculating a multipath compensation value by computing a function containing the sampled correlator magnitudes as terms;
- and
- adjusting the determined pseudorange measurement by an amount indicated by said calculating step.
A positioning system receiver comprising:
- code tracking means for synchronizing a receiver-generated positioning code with a received positioning code wherein said code tracking means comprises generating means for generating magnitudes of at least four samples of a correlation function:
- ranging measurement means for determining ranging measurements from a correlation function signal received from said code tracking means;
- and
- measurement compensation means for removing multipath-induced bias from ranging measurements determined by said ranging measurement means wherein said measurement compensation means removes multipath-induced bias with a multipath indicator function, the multipath indicator function containing the generated correlator magnitude as terms.
Dependencies are inferred from the claim text.