Closed-loop infrared countermeasure system using a high frame rate infrared receiver with nulling sequence

Abstract

A missile tracking and deflection system for protecting a platform includes a missile warning system for detecting the presence of a missile and generating a warning signal. A countermeasure processor receives the warning signal and analyzes characteristics of the missile to prioritize a trajectory signal. A track processor receives the trajectory signal and generates a pointer signal. The system also includes a receiver, which is positioned by a pointer that receives the pointer signal, for receiving a passive and/or active signature of the missile to confirm the presence thereof. The countermeasure processor then directs a laser beam at the missile to determine its operational parameters and receives an active signature from the missile. The receiver delivers the passive and/or active signatures to the countermeasure processor and the track processor, wherein the track processor updates the pointer signal and the countermeasure processor generates a jam code delivered by the laser beam to divert the trajectory of the missile away from the platform. A nulling or blanking signal may be used during generation of the laser beam to improve reception of the active signature.

What is claimed is:  
     
       1. A missile tracking and diverting system, comprising: 
       a countermeasure processor for generating a trajectory signal of a detected missile;  
       a track processor for receiving said trajectory signal and generating a pointer trajectory signal;  
       a pointer for receiving said pointer trajectory signal to position said pointer toward the missile and track the trajectory of the detected missile;  
       a laser positioned by said pointer; and  
       an infrared receiver comprising an infrared focal plane array that integrally and simultaneously combines a tracking camera and a laser receiver, said infrared receiver positioned by said pointer;  
       said countermeasure processor simultaneously generating an initiation signal and a blanking signal,  
       said initiation signal causing said laser to generate a periodic pulsed signal that includes a laser pulse within a laser pulse interval,  
       said blanking signal instructing said focal plane array to initiate a hold-off time which is longer than said laser pulse, prior to turning said infrared receiver on so as to allow for back scatter decay,  
       said countermeasure processor generating a jam code for inclusion with said periodic pulsed signal to divert the trajectory of the detected missile.  
     
     
       2. The system according to  claim 1 , wherein said sequence of periodic laser pulses is reflected by the missile to generate an active signature, and wherein said infrared receiver, after termination of said blanking pulse, generates at least two integration intervals for the purpose of capturing said active signature to determine range information of the missile. 
     
     
       3. The system according to  claim 2 , wherein said at least two integration intervals are of variable duration. 
     
     
       4. The system according to  claim 2 , wherein said infrared receiver remains on alter said at least two integration intervals terminate for a read-out signal interval which ends at about the same time as said predetermined interval. 
     
     
       5. A method for diverting the trajectory of a missile, comprising: 
       analyzing characteristics of a detected missile with a countermeasure processor which generates a trajectory signal;  
       processing said trajectory signal to generate a trajectory pointer signal;  
       receiving said pointer signal in a pointer that follows the missile trajectory, said pointer positioning a laser and an infrared receiver which has a single focal plane array that integrally and simultaneously combines the functions of a tracking camera and a laser receiver;  
       simultaneously generating an initiation signal and a blanking signal from said countermeasure processor;  
       generating a sequence of periodic laser pulses that includes a laser pulse within a laser pulse interval from said laser upon receipt of said initiation signal;  
       receiving said blanking signal in said infrared receiver;  
       initiating a hold-off time of said focal plane array upon receipt of said blanking signal by said infrared receiver, prior to turning said infrared receiver on, wherein said hold-off time is longer than said laser pulse so as to allow back scatter decay of said laser pulse; and  
       generating a jam code by said counter-measure processor for inclusion with said laser pulse to divert the missile from its trajectory.  
     
     
       6. The method according to  claim 5 , further comprising: 
       turning said infrared receiver on after completion of said blanking signal; and  
       observing an active signature by said laser receiver that is a reflection of said sequence of periodic laser pulses by the missile.  
     
     
       7. The method according to  claim 6 , further comprising: 
       employing at least two integration intervals by said laser receiver to observe said active signature for the purpose of determining range information.  
     
     
       8. The method according to  claim 7 , further comprising; 
       varying said integration intervals.  
     
     
       9. The method according to  claim 7 , further comprising: 
       leaving said laser receiver on alter completion of said employing step until completion of said predetermined interval.