614 



DISPLAY SYSTEM DESIGN PROBLEMS 



Ground Return 



Target 



A Scope 



J Scope 



Target Echo 



L Scope K Scope 



Fig. 12-5 Amplitude-Modulated Displays. 



as either intensity-modulated signals (applied as positive signals on the grid 

 of the CRT) or as amplitude-modulated signals (applied to the vertical 

 deflection plates together with the receiver video signals). 



The type A display was first used because of its simplicity of mechaniza- 

 tion. Its limitation in wide-angle coverage radar systems is apparent, for 

 it is incapable of presenting the target directional coordinates. The 

 advantages of the type A scope are numerous. It is easily interpreted 

 (all oscilloscopes use this type of sweep). The amplitude modulation of 

 the A scope has better bandpass characteristics than intensity-modulated 

 presentations because the signal is traced along a longer path on the 

 phosphor screen than the signal of an intensity-modulated presentation. 

 Therefore, there is not as much signal compression as in other displays. 

 It is the most adaptable scope for observing signals through interference 

 for this reason. Lastly, the dynamic range of signal display is greatest of all 

 the displays because none of the cathode ray tube electrical characteristics 

 except the deflection sensitivity enter into the modulation reproduction. 

 The signal may be displayed along the full scope face if the video amplifier 



