208 



REFLECTION AND TRANSMISSION OF RADIO WAVES 





k\l^ht\M^^^%^ PB4Y 



_i 



lE^^^^'^^Yy^^E^. 



(c) 

 2SNB90' 



^1 



H 



^5 



fS 



n 



-||!B^i|i^ 



m 



ift 



ELAPSED TIME 



SNB 



SNB 



SNB 



Fig. 4-30 Sample Time Function Plots of Range Noise from the (a) PB4y (Four- 

 Engine Bomber) at 180° Target Angle, (b) ANB (Two-Engine Transport) at 180° 

 Target Angle, and (c) SNB pair. 



aspect angles of 0°, 90°, and 1 80°, and of two SNB's at °90. Both the range 

 noise spectrum and its probability distribution are shown. 



The distribution of the apparent reflection center in range generally lies 

 wholly within the target, as can be seen from the curves at the right in 

 Fig. 4-31. In this respect, range noise differs from angle noise. The reason 

 lies in the different methods used for error detection in angle and in range. 



As in the case of angle noise, multiple targets which are not resolved will 

 give rise to much higher noise levels than a single target. 



4-9 PREDICTION OF TARGET RADAR CHARACTERISTICS 



Quantitative measurements of radar characteristics require special 

 instrumentation which is not widely available and is costly. Furthermore, 

 targets of interest may not be available for measurement. For example in 

 a problem of the type outlined in Chapter 2, it is highly unlikely that such 

 definitive target information will exist. Hence great importance attaches 

 to methods whereby the characteristics of interest may be calculated. As 



