1 2-8] DEVELOPMENT OF REQUIREMENTS FOR A DISPLAY SYSTEM 653 



to be less than 5° rms. The pilot will have to maintain the center of the 

 scope within the error circle for a successful approach. 



Aircraft attitude will be indicated by the motion of an inverted tee 

 representing the aircraft. Roll and pitch of the aircraft will correspond to 

 rotation and vertical movement of the tee relative to a horizontal reference 

 line. 



The primary features of the display unit which we have just specified are 

 indicated in Fig. 12-34. In operation, the pilot attempts to fly the tee into 

 the error circle, although it is actually the circle which moves horizontally. 



Expected Spread of 

 Target Range 



60 Azimuth 

 Search Pattern 



Error Circle 



Attitude Tee 



Target 



Elevation Strobe 



Azimuth Strobe 



Fig. 12-34 AI Display Specified for Vectoring and Search Phase. 



The data in Paragraph 12-7 are applicable to several aspects of the search 

 display design. In particular, the data in Fig. 12-26 indicate some of the 

 effects on detection of high ambient illumination as a function of receiver 

 gain and pedestal voltage in a typical case. It is apparent in that figure 

 that optimum performance will be provided when specific related values 

 of receiver gain and pedestal voltage are used. Means therefore should be 

 provided in the search display for ensuring that optimum settings for these 

 controls are maintained. One possibility is simply not to provide any 



