GB2086685A - Overkill detector for a radar system - Google Patents

Abstract

An overkill detector for use with the radar systems of a number of weapon delivery sites includes an asynchronous code generator for modulating a unique code on each of the illuminating radar beams. A code detector is also provided at each site and continuously monitors the return radar signal for the codes of adjacent weapon delivery sites. If a code from another site is detected, an alarm is activated which advises the site operator that the target is being tracked by the radar of more than one weapon delivery site. <IMAGE>

Description

SPECIFICATION Overkill detector for a radar system Technical Field This invention relates to a system for use with search and track radar at a weapon delivery site to aid an operator in identifying when a single target is being tracked by the radar of an adjacent weapon delivery site.

Background Art Automated weapon delivery systems for missiles, or the like, are generally known and often employ a search and track radar to identify targets which are in the area assigned to the missiles. In many military situations, a number of missiles are deployed at spaced locations along the ground and each site may include a separate radar system. In order to search both lower and higher elevation, the search and track radar at each site may search an area which overlaps the field of adjacent sites. Accordingly, if a site operator is not aware of this, there is the possibility that a single target could be attacked by more than one missile, creating a situation known generally as "overkill".In order to prevent the firing of more than one missile at a single target, if the operator is advised that the radar of an adjacent site is tracking the same target, he will then be in a position to avoid an overkill situation.

The problem of overkill with gun emplacements is known and various techniques have been employed to reduce the likelihood of overkill. In U.S. Patent No. 2,763,856 issued September 18, 1 956 to M. Lattmann for "Control Apparatus", a system for directing a number of guns is disclosed. A computer receives information locating a specific target with respect to remote stations. This elaborate and comprehensive system allows a commander to select a particular target. The information concerning this target is transmitted to the particular remote gun emplacement strategically located for firing at the target. The operator at the remote gun varies his viewing angle and this information is transmitted back to the computer. Then the proper angle to the target is determined by the computer.The commander at the main station then knows that a particular remote gun emplacement has sighted the target of interest and can direct firing as desired.

Another technique for preventing overkill is disclosed in U.S. Patent No. 3,270,340 issued August 30, 1 966 to C. Hammack for "Method of Echo Grouping". The apparatus disclosed in this patent describes a technique for grouping echoes from a single reflecting target detected at several receiving stations. A tracking filter is provided for each transmitter in the system. Each tracking filter is designed to track selected signals in the doppler spectrum of one of the transmitters. Each tracking filter is manually adjusted or set on a selected echo by an operator who may employ a spectrum analyzer. When adjusted to a selected dopper echo, one of these tracking filters continues to track the doppler frequency of that particular signal and none other.

Of general interest are U.S. Patent No.

3,508,258 issued April 21, 1970 to L. Sjostrom for "Method and Arrangement Choosing a Target With definite Order Number by Means of a Target Seeker"; U.S. Patent No.

3,754,249 issued August 21, 1973 to S.

Kearney for "Laser Fire Control System Small Boat Application"; U.S. Patent No.

3,733,604 issued May 15, 1973 to H. Smith for "Aircraft Guidance System"; U.S. Patent No. 2,950,880 issued August 30, 1 960 to B. Chance et al for " Method of and Means for Guiding Missiles"; U.S. Patent No.

3,383,683 issued May 14, 1968 to K. Harriger et al for "Pulse Doppler Radar System for Selectively Inhibiting Target Detection"; and British Specification 954,098 published December 11, 1 973, for "Pulse Echo Type Detecting System".

Disclosure of Invention It is an object of the present invention to provide a simple, and yet reliable, technique for use in radar systems of a number of weapon delivery sites to identify potential overkill situations which could result in the firing of more than one missile at a single target.

According to the present invention, each one of a plurality of missile delivery systems has a search and track radar which includes a distinct code modulated on the illuminating radar beam. When the reflected radar signals are received at one location, a code comparator makes a comparison between a code modulated on the return radar signal, if any, and the stored codes to identify codes of other missile delivery sites. If a match exists, the operator at this site knows that the target is being tracked by the search and track radar of another missile delivery system.

According to the present invention, a track and search radar for a missile delivery system utilizes an illuminating beam with a particular code modulated thereon. In the event that the area searched by the radar overlaps the area searched by an adjacent radar, a return radar signal may be that from the radar of another missile delivery system. To identify this condition, a code detector attached to each radar receiver has stored therein the codes which could be employed by the radars of the other missile delivery systems. If this comparison is positive, the operator knows that a potential overkill situation exists because more than one tracking radar is illuminating the target of interest.

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following description of preferred embodiments and accompanying drawings.

Brief Description of the Drawing The sole Fig. is an illustration showing a potential overkill situation; and also a block diagram of one embodiment of an overkill detector according to the present invention.

Best Mode for Carrying Out the Invention Referring now to the sole Fig. there is seen one embodiment of an overkill detector for a radar system according to the present invention. In many military situations, there are a number of sites deployed in a predetermined manner to detect and attack targets. One or more weapons, such as missiles, may be located at each of the sites and are normally under the control of an operator who can fire the missile to attack an enemy target. Such weapon delivery systems often include a search and track radar for scanning an assigned sector for potential target, such as an aircraft 10.

In order to cover both lower and higher elevations, it is normal that adjacent sites, such as site A and site B, have portions of their assigned sectors that overlap with adjacent sites, this being shown generally as area 1 2 in the drawing. The search and track radar at each site includes an antenna, such as antenna 14a and antenna 14b, which scan an illuminating radar beam, such as radar beam 1 6a and 16b, throughout the area in the assigned sector. If a target, such as aircraft 10, enters the sector scanned by the illuminating radar beam 16a, a return radar signal 1 8a is scattered back toward the radar antenna 14 at site A.At each of the sites, a radar receiver, such as radar receiver 20a, is attached to each radar antenna and forms a video signal which is presented to a video display, such as video display 20a, so the site operator can observe the movement of the aircraft 10.

As is seen in the drawing, a potential overkill situation exists if the aircraft is in overlap area 12 since the movement ofthe aircraft can be observed on the video display at two or more sites. As a result, each of the site operators at the two adjacent sites might simultaneously fire a missile to attack the aircraft 1 0. Thus, two missiles would converge on the aircraft 10 when only one would be sufficient to eliminate the target.

The overkill detector of the present invention idenitifes this potential overkill situation to the site operators. According to one embodiment, a code generator 30 of the asynchronous type is provided and connected in the radar systems at all of the weapon delivery sites. The code generator 30 creates a single unique code from a large number of possible codes, and it is connected to a transmitter 32 of the radar system at each site so that the code is modulated on the illuminating beam. Simply stated, code A is modulated on the illuminating radar beam at site A. The code for each site is distinct from the codes of every other weapon delivery site. In preferred form, even though code A is different from code B, there is a finite number of codes so it is not necessary to know the exact code of the other sites.The overkill detector also includes a code detector 34 at each site and each code detector 34 is connected to the radar receiver 20 so that it can receive the coded signal modulated on the radar signal reflected by the aircraft 10. The code detector 34 is asynchronous and can check any receive code on a return radar signal against the large number of possible codes to see if it is from another site. An overkill alarm 36 is provided and is connected to the code detector 34 at each site. Although numerous different codes and coding techniques could be used in the present invention, one simple technique would involve a pulse modulation where each site corresponds to a different pulse width.

In operation, each search and track radar for the weapon delivery system at each site, such as site A and site B, scan the radar beam 1 6 over an assigned sector. Radar return signals 1 8 are picked up by each antenna 1 4 and are presented to a video display 20 so that the site operator can observe and track the movement of the aircraft 1 0. If the aircraft 10 is in an overlap area between site A and site B, such as area 12, the antenna 1 4a at site A may also pick up and return radar signal 40a which is from the illuminating radar beam 1 6b at site B. Most likely, the radar antenna 1 4b has also received radar signal 40b which is from the illuminating beam 1 6a at site A.Consider now the situation at site A, this reflected radar signal 40 has code B modulated thereon and the code detector 34 senses that this code is not code A but is in fact one of the plurality of codes which are assigned to the other weapon delivery sites. The code detector 34 then provides a signal to activate the overkill alarms 36 and appraise the operator that a return radar sig nal from another site has been received.

It will be understood by those of ordinary skill that the present invention could be used with many other types of radar systems, or the like. For example the radar system used in conjunction with the present invention could be a laser radar, or even with a sonar system.

Although this invention has been shown and described with respect to a preferred embodiment, it will be understood by those skilled in this art that various changes in form and detail thereof may be made without de parting from the spirit and scope of the claimed invention.

Claims (4)

1. An overkill detector for use with a plurality of weapon delivery sites, each site having a radar system including a transmitter connected to an antenna for providing an illuminating radar signal, each site also including a receiver connected to said antenna means for receiving return radar signals, comprising: code generator means attachable to said transmitter at each site for providing a first code which is modulated on said illuminating radar signal, said first unique code being one of a plurality of codes; code detector means attachable to said receiver of said radar system at each site for sensing said plurality of codes to identify any one of said plurality of codes other than said first code; alarm means connected to said code detector means to provide an alarm indication of the receipt of any one of said plurality of codes other than said first code; and whereby said alarm indicates that the target displaced by said receiver of said radar system is being tracked by the radar system of another site.

2. An overkill detector according to claim 1, wherein said first code modulated on said illuminating radar signal is a pulse width modulated code.

3. An overkill detector according to claim 2, wherein said first code has a particular width that identifies a particular site, and wherein said code detector means can distinguish said first code from any other codes modulated on said return radar signal.

4. A code detector according to claim 1, further including a video display means attached to said receiver on which a site operator can observe radar return signal indicative of a target.