2-13] AEW TARGET RESOLUTION REQUIREMENTS 77 



Thus, it is seen that the fact that only 10 of the 20 targets were resolved 

 initially does not in itself degrade system performance. So long as resolution 

 is sufficient to resolve additional targets faster than the interceptor launch- 

 ing rate, system performance will not be affected for the assumed tactical 

 doctrine.^ A further examination would disclose that as few as 5 targets 

 could be indicated by the initial early warning information provided that 

 the subsequent "break-up" of targets was sufficient to keep pace with deck- 

 ready interceptor launch rate. 



The vectoring phase imposes additional resolution requirements. The 

 assumed tactical doctrine requires that individual interceptors be directed 

 against individual targets. Thus, both targets and interceptors must be 

 separately resolved and tracked in this phase. 



An inspection of the tactical geometry of Figs. 2-12 and 2-18 discloses 

 that contact between targets and interceptors will take place at ranges 

 that are seldom greater than 75 n.mi. from an AEW aircraft. The majority 

 of contacts will be less than 50 n.mi. from an AEW aircraft. Thus, if 

 the AEW radar resolution and the interceptor tactics are chosen to ensure 

 that substantially all the targets and all the interceptors can be separately 

 resolved at ranges of 75 n.mi. or less from the AEW aircraft, little or no 

 degradation in system performance will result if at least 5 separate targets 

 are indicated at the early warning range (150 n.mi.). 



Now the foregoing tactical requirements may be translated into radar 

 performance requirements. With a radar, it is possible to measure three 

 quantities directly (see Paragraph 1-4) — range, angle, and velocity along 

 sight-line to target. Resolution between targets may be done on the basis 

 of any or all of these. 



Fig. 2-20 shows a particularly difficult case that could exist for the hypo- 

 thetical threat. The target threat complex is approaching along a radial 

 line which passes through the AEW aircraft and fleet center. The location 

 of each threat element relative to the AEW aircraft is shown in the ex- 

 panded view. As can be seen, the angular differences between adjacent 

 threat elements are of the order of 4°. The range difference between ad- 

 jacent elements varies from about 2.5 n.mi. for the extreme outer threat 

 elements to less than 1 n.mi. for the central elements. In the case of the 

 two center elements, the range difference is zero. The differences in radial 

 velocity components of adjacent elements vary from about 20 fps for the 

 outer elements to fps for the central elements. 



From the diagram, it is seen that an angular resolution capability of 4° 

 or less will provide the stipulated tactical capability. However, this is 

 not the only means for meeting the requirement. A range resolution ca- 



^This analysis does not consider the possible benefits of finer resolution to the assignment 

 procedure. These might be significant in a practical case and should be taken into account. 

 The analysis of this problem is too complex for consideration in this example. 



