We assume that the observed point-to-point transmission loss fluctuations arise 

 from two independent causes -- the variation of transmission loss with range and 

 a temporal fluctuation . We characterize the latter by a standard deviation Of 

 and assume that the standard deviation of the former is given by the preceding 

 "theoretical" standard deviation, o^, derived from the computation of the trans- 

 mission loss curve . Accordingly, the standard deviation of the experimentally 

 observed fluctuation, o~ e , is given by 



:j + a^ 





[a f (db)] 





*1 



A 2 



A3 



4.0 



3.8 



4.0 



3.4 



2.7 



2.6 



2.6 



2.8 



3.2 



2.0 



2.2 



2.4 



Using a e and a^ from Table 1, we have calculated Of. The results are pre- 

 sented in the following table . 



Standard Deviation of Temporal Fluctuations 



Area I - 3000 cps 



Area II - 3000 cps 



- 1300 cps 



- 700 cps 



If this approach has any validity, the results are interesting. Within Area II, 

 the behavior of the Of 's does not appear to be related in any obvious way either 

 to the A's or to frequency. The only obvious comment is that within Area II, 

 the CJf's at 3000 cps, fall between 2.6 and 3.4, whereas in Area I, they range 

 from 3.8 to 4.0 db. Numerically, the difference is not insignificant. If this 

 result is physically significant it represents the only discoverable difference 

 between Area I and Area II. But it should be noted that the observed cr e 's are 

 quite similar (see Table 1) although wind speeds differed (see page A-2). 

 Hence the differences between the Of 's stem from differences in the theoreti- 

 cal curves as reflected by the a t 's . The differences between the computed 

 curves, in turn, arise from the small differences in duct width and velocity 

 gradient, used in making the calculations. (See Appendix B, paragraph 3.) 



14 



2rtlmr 2)/?Uttle,3nr. 



