Method and apparatus for reducing the amount of shipboard-collected calibration data
First Claim
1. A method for reducing the time a ship must be maintained on station during a run to gather data for the calibration of an array of direction finding antennas located on the ship and coupled to a direction finding system, comprising the steps of:
- determining an optimal set of calibration frequencies for the calibration of the array; and
, using a reduced set of the optimal set of calibration frequencies for gathering the shipboard data.
3 Assignments
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Accused Products
Abstract
A system is provided for reducing the time that a ship must be maintained on station to collect calibration data by reducing the frequencies at which calibration data is to be collected. Since it is impractical to consider calibrating over elevation angle and polarization on the full-scale ship, an accurate scale model and test facility are utilized, with surface wave data being collected from the ship before model-based data can be utilized. In the subject system, the number of calibration frequencies used aboard ship is dramatically reduced by as much as 80%, thus reducing the time the ship must be on station when doing a calibration run. In one embodiment, the shipboard surface wave data for one elevation and one polarization is combined with surface wave and sky wave data from the scale model to generate an array manifold or database used in subsequent direction finding activities. In order to minimize the frequencies at which shipboard data is collected, the set of frequencies used for shipboard calibration is limited to a subset of all the original calibration frequencies. The number of frequencies used for shipboard calibration is reduced by selecting frequencies which generate adjustment, or weighting factors which are valid over a wide bandwidth.
8 Citations
13 Claims
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1. A method for reducing the time a ship must be maintained on station during a run to gather data for the calibration of an array of direction finding antennas located on the ship and coupled to a direction finding system, comprising the steps of:
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determining an optimal set of calibration frequencies for the calibration of the array; and
,using a reduced set of the optimal set of calibration frequencies for gathering the shipboard data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for selecting calibration frequencies for calibrating an antenna array aboard a ship coupled to a direction finding system in which an optimal set of calibration frequencies for the array has been specified, comprising the steps of:
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determining in what regions of the electromagnetic spectrum there are higher densities of the calibration frequencies in the optimal set; and
,using a reduced set of the optimal set of calibration frequencies to calibrate the antenna array, the reduced set having more calibration frequencies where there are higher densities of the calibration frequencies in the optimal set and less calibration frequencies where there are lower densities of the calibration frequencies in the optimal set, whereby the calibration frequencies in the reduced set are chosen based on measured response characteristics of the antenna array. - View Dependent Claims (11, 12, 13)
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Specification