1.0 INTEMXJOriCM 



The assessment of airborne man-made radio noise began as an effort to 

 more completely understand the factors influencing performance of Meteor Burst 

 Communication Systems (KBCS). These systems are under investigation here at 

 the Naval Ocean System Cer.t?r (NOSC) to detent :,<» their potential application 

 to the Minimum Essential Smergenry Communi'^Uiwn Network (MEECN) . Operation 

 of MBCS depends upon the reflection of vhf ',30-100 r<Hs or more) radio signals 

 from ionized meteor trails as shown '^ figure 1. l^.-.-^ag required to evaluate 

 the performance of these systems invol.C~ trai.smissl and reception of vhf 

 signalB both on the ground and when airborne. Ext *■«*! iterference affecting 

 the reception of these signals includes galactic - Li?, local atmospheric 

 noise, and man-made noise. Of the three types of ..■•■-:«! ' >n "snce encountered 

 during airborne tests, man-made noise near metropolis a!. *»'•.' <? was the most 

 severe. The effect of this interference on a MBCS is to increase the system 

 waiting time for transmission of an error-free message. 



The airborne MBCS experiments have shown that man-made radio noise can be 

 measured at distances in excess of a hundred miles from large metropolitan 

 areas. Noise was found to increase with altitude and the minimum noise level, 

 galactic noise, was found only over open ocean. In general, the level of man- 

 made radio noise was worse than expected and it was decided that an assessment 

 of the characteristics of airborne man-made radio noise would be necessary to 

 evaluate the utility of Meteor Burst Communication Systems. 



Figure 1. Meteor Burst Communication System. 



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