BAND W IDTIl AM) TKA \S.\I ISSlOX PKRIORM ANCE 



569 



wave-guide conductors. This diminishes the premium on ruggcdness pro- 

 vided sullicient power is available so that ruggedness with respect to noise 

 is not critical. 



2. Since there is no fading and all spans can be of appro.ximately equal 

 length, all spans will possess the same loss, approximately. This situation 



CIRCUIT LENGTH IN MILES 



Fig. 28 — Variation of circuit length with number of repeater sections in an AM system 

 with fixed power capacity and noise figure. 



is favorable to all systems but is most favorable to PCM, which gets no 

 credit for low loss spans. 



3. In the case of wave guide, frequency space may be much less precious 

 than in coaxial or radio relay transmission. 



4. There is a possibility that many small repeaters should replace the few 

 higher powered repeaters used in radio relay. 



These different considerations may lead to a different evaluation of the 



