78 THE DEVELOPMENT OF WEAPONS SYSTEM REQUIREMENTS 



Target Complex Broken up into Resolution Cells 5° x 1 n.mi. 

 \~ Unresolved ,Z~Zr7-r~c^ 



20 Targets Spaced 5 n.mi., 

 Apart Resolved into 17 Elements 



75 n.mi. 



' / 



^^ Resolution Cell 



I / 5° X 1 n.mi. 



I / 



I / 



I / 

 I / 

 I / 

 I / 

 I / 



^5° Azimuth 

 Beamwidth 



12-Msec Pulsewidth = l n.mi. 



AEW Aircraft 

 To Fleet Center 

 Fig. 2-20 AEW Radar Resolution Capacity at 75 n. 



pability of 0.5 n.mi. would permit resolution of 19 out of the 20 targets 

 at 75 n.mi. range. (The two center targets would appear as one if range 

 resolution were used.) At 150 n.mi., 15 targets would be seen. 



Similarly, various combinations of range and angular resolution capa- 

 bilities may be employed. For example, the diagram shows that an angular 

 resolution capability of 5° coupled with a range resolution of 1 n.mi. will 

 allow resolution of 18 of the 20 targets at 75 n.mi. range. At 150 n.mi., 

 15 separate targets will be indicated. 



Several other factors must be considered in a practical treatment of the 

 resolution problem. The individual threat elements will be unable to main- 

 tain perfect station-keeping with respect to each other. Errors in relative 

 heading, velocity, and position will exist at any given time. This will cause 

 the actual target positions and velocities to be distributed around the values 

 shown in Fig. 2-20. We shall assume that these errors are small relative to 

 the size of a resolution element for the example. However, if these errors 

 were of the order of magnitude of a resolution element, they could cause 

 substantial modification of the tactical resolution capability. 



