9-51 



ANGLE TRACKING SYSTEM ORGANIZATION 



483 



mode may be used as search loop components. The stabilization, or inner 

 loop, primarily isolates the antenna from aircraft motion as described in 

 Paragraph 8-30; it provides measurements of the tracking line rates in the 

 presence of external space disturbances. The angle track loop includes the 

 stabilization loop as well as the radar equipment; it provides the magnitude 

 and direction of the space error between the sight line and tracking line Et 

 in Fig. 9-2. 



Simplified Angle Track Loop. As noted above, the two channels 

 are nearly identical.^ Therefore, for purposes of analysis, all of the sight 

 line motion may be referred to only one channel, rather than be distributed 

 between the two, to establish the necessary loop specifications. The form 



Computer L oop 



Target Line-of-Sight r-- — , — iR.,, | — n Aa 



Angle in Space r"*! '^°'^P"*^'' hr'w-*lGAl 1 Aircraft Angle in 



Gc I +1 '-- ■' I 



^— ! I 



Track Loop 

 Transfer Ratio 



Fig. 9-4 Simplified Block Diagram of One Channel of Angle Tracking and 

 Stabilization Loops. 



Gi = radar receiver, amplifier, bandwidth shaping; Go = power amplifier, actuator, 



antenna structure; Gs = rate gyro; Et = radar angle error; Er = rate loop error; 



GcGa — computer, pilot, aircraft (or missile and autopilot only) (not easily 



described mathematically); Vr = rate command 



TRANSFER FUNCTIONS 



Gi 



Gr = 



\ ^2/ 



G, 



TL \ ^2/ 



1 + G2G3 



1 



V CO 2/ 



Et 



\ COi/\ 0)3/ V CUi/V CO3/ 



K = K, 



^Although both channels may not be required to have the same performance or the same 

 component design for a given tracking problem, it is desirable to consider that the same 

 performance may be required of either channel because of the wide variety of attack conditions 

 that may occur. 



