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Browse Prior Art Database

Map Matching System

IP.com Disclosure Number: IPCOM000095945D
Original Publication Date: 1964-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Anuta, PE: AUTHOR [+2]

Abstract

The system produces a navigational position fix from side-looking radar return data by comparison with a previously stored radar map. A digital computer is employed for correlating, or comparing, the fresh radar data with the stored map.

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Map Matching System

The system produces a navigational position fix from side-looking radar return data by comparison with a previously stored radar map. A digital computer is employed for correlating, or comparing, the fresh radar data with the stored map.

The side-looking radar emits a pulse beam that scans a single line at a time across the terrain. Accumulation of the return information of an area so scanned as a craft moves along its flight path provides a radar map. The return signals forming the map are broken into fixed equal ground increments, or cells, and quantized.

The reference radar map is prestored on a magnetic drum, for example, and it covers a larger area of the terrain than that being immediately scanned. This prestored map is constructed such that the ground increments, or cells, are identical to those being scanned and are also quantized at a uniform level. Each line of fresh radar data is compared against the prestored map on a line-by-line, cell-by-cell basis and the points of maximum correlation are stored in the computer memory.

If the degree of correlation between the newly obtained data and the prestored map is below a certain predetermined amount, skew is assumed to exist between the two maps, that is, information is being received angularly with respect to that in which it was originally stored. Skew correction is accomplished by shifting a block of cells to other lines, e. g., four cells on the original line 1, four cells transferred...