Median filter for reducing data error in distance measuring equipment
AssigneeAllied Corporation
InventorsRobert J. Kelly, Danny R. Cusick
Life of this patent
Estimating the term…
Abstract
A set containing an odd number N of successive raw range data samples from precision distance measuring equipment is established. The set is arranged in ascending order of sample magnitude. The median member of the ordered set, i.e. the (N-1/2+1 member, is selected for processing in an alpha-beta type digital filter. The filter output is compensated for the delay introduced by using the median member of the set as the input to the alpha-beta filter. The compensated filter output is utilized as the distance input signal to a display or aircraft flight control system.
Claims6
The method of processing raw data output of distance measuring equipment comprising,
- assembling a set comprising N number of periodic successive raw data sample outputs from airborne distance measuring equipment, said raw data samples comprising measurements of range, taken during discrete periodic sampling intervals, between said airborne distance measuring equipment and a selected ground station, said number N being an odd number, said set of successive data samples including the data sample for the current sampling interval;
- arranging said N set of data samples in ascending order of value;
- selecting the median sample of said arranged set of data samples, said median sample comprising the (N-1)/2+1 sample of said arranged set of data samples;
- and
- combining by means of a digital filtering process said selected data sample with a value of range predicted for the current sampling interval to produce an estimated value of range for the current sampling interval and a predicted value of range for the sampling interval next following the current sampling interval;
- and
- displaying said estimated value of range upon a distance indicator.
Dependencies are inferred from the claim text.