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Browse Prior Art Database

Radar Range Marker Determination Circuit

IP.com Disclosure Number: IPCOM000091469D
Original Publication Date: 1968-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Goldman, AF: AUTHOR

Abstract

This circuit pertains to a radar system designed which makes a contour map by scanning a radar over some wide angle. It sees only targets that are at particular range intervals, for example, every hundred meters. The circuit unblanks the oscilloscope display only if a return from the radar is one of these multiples of, for example, a hundred meters. In addition, the display is unblanked if a large change in contour is realized from passing from one angle of the azimuth to the next particular angle. For example, if it is a steep hill and the elevation changes from a hundred meters up to five hundred meters, it is desirable to realize that this change occurs and therefore unblank the scope for a period of time equal to the number of hundred meter intervals passed, i.e.

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Radar Range Marker Determination Circuit

This circuit pertains to a radar system designed which makes a contour map by scanning a radar over some wide angle. It sees only targets that are at particular range intervals, for example, every hundred meters. The circuit unblanks the oscilloscope display only if a return from the radar is one of these multiples of, for example, a hundred meters. In addition, the display is unblanked if a large change in contour is realized from passing from one angle of the azimuth to the next particular angle. For example, if it is a steep hill and the elevation changes from a hundred meters up to five hundred meters, it is desirable to realize that this change occurs and therefore unblank the scope for a period of time equal to the number of hundred meter intervals passed, i.e., unblank it for four pulses rather than unblanking it for a long period if the land is flat.

This circuit provides an unblanking pulse to a radar display when the detected range measurement from a resolution element is equal to a preselected multiple of the minimum measurable range interval. It also provides a pulse for each change in range between adjacent range resolution elements of a preselected value. For example, the display is unblanked for T seconds if a range measurement is equal to x +/- y meters and kT sec, where k = 1/2N, N = number of resolution elements, for each x meter difference in adjacent range measurements.

The circuit uses digital data processing to accomplish the unblanking of the display. The range is determined using a range counter arranged in a series of N decade counters of n stages each so that groups of four bits are decoded into decimal multiples of the minimum discernible range. The decade counters count a frequency f1 which is a high frequency, e.g., 15 megacycles, selected equal to a range interval. Frequency f2 is also used to trigger the radar transmitter and is usually a much lower frequency than frequency f1, e....