136 THE DEVELOPMENT OF WEAPONS SYSTEM REQUIREMENTS 



pulse radar is entirely reasonable for the high-altitude (i.e. clutter-free) 

 operation required in this tactical application. 



To assist lock-on of the missile seeker, the AI radar also is required to 

 provide range and angle slaving signals to the missile seeker. The angular 

 accuracy is not particularly critical, since the missile seeker beamwidth is 

 relatively wide, perhaps of the order of 10° to 12°. Range accuracy, on the 

 other hand, can be fairly critical. If the missile seeker is assumed to operate 

 with a pulsewidth of 0.5 /xsec (250 ft) and a l-jusec (500-ft) range gate, then 

 range errors in excess of about 150-200 ft can begin to affect seeker lock-on 

 capability. The range error specification previously derived (Table 2-4) 

 dictated allowable errors of about this magnitude (bias error plus la value 

 of random error). In a practical case, this condition would dictate a more 

 comprehensive analysis of seeker AI radar interrelations. 



2-30 SUMMARY OF AI REQUIREMENTS 



Reliability: 90 per cent for 3-hour operation 



Search Pattern: 60° azimuth; 

 17° elevation; 

 Stabilized in roll and pitch 



Search Range: 20 n.mi. 



Search Display: Vectoring heading command 

 Time to collision 

 Attack altitude 

 Range to target 

 Interceptor roll and pitch 

 AI radar target detection information 



Detection Range: Yl n.mi. (90 per cent probability) with 6-second 

 lock-on time 

 14 n.mi. (90 per cent probability) with 12-second 

 lock-on time 



Lock-on Range: 10 n.mi. at a closing speed of 2000 fps with 90 per cent 

 probability 



Look-Angle: ±60° in azimuth and elevation 



Required Computation: Lead collision (see Equations 2-59 to 2-62) 



Required Accuracies: See Table 2-4, Paragraph 2-28 



Dynamic Inputs: See Fig. 2-45 



