650 



DISPLAY SYSTEM DESIGN PROBLEMS 



logical factors indicated that there might be an interaction between the 

 radar noise level and the scale factor used on the scope. An experiment 

 was therefore designed in which the amplitude of the radar noise, the scope 

 scale factor and the frequency of data inputs to the system were the 

 variables. The results of this study are summarized in Fig. 12-33. The 



2 4 6 8 10 12 

 NOISE -RMS mils 



(a) 



2 4 6 8 10 



NOISE -RMS mils 



(b) 



2 4 6 8 10 12 

 NOISE -RMS mils 



(c) 



CO = frequency (cps) 

 K = scope sensitivity 



4 6 8 10 

 NOISE- RMS mils 

 (d) 



Fig. 12-33 Performance vs. Noise for Variable Forcing Frequency and Scope 



Sensitivity. 



diagonal on the curves labeled ideal performance is the performance that 

 would obtain if the human operator did not contribute to the error of the 

 system. Analysis of the data indicated that there is no significant difference 

 in system performance when the 0.3° /inch or the 2.5° /inch scope sensitivity 

 is used. These results suggest that there is no need to have a scale factor 

 more sensitive than 2.5° /inch, and that the scale factor is independent of 

 the radar noise level. 



