TYPE-O CARRIER SYSTEM 



roi 



])lu^-iii filter iv\'er.sible in il.s .socket, this groupiiiji; cuu be made to serve 

 two channels as follows: 



180-184 Transmitting 

 192 IIH) Keceivinj-- 

 A similar i)aire(l liltei" serx'es 



184 188 Transmitting 

 188 192 Keeeivin"- 



nd 



and 



192 19(1 Transmit tiiio- 

 180 181 deceiving 



188 192 ^^ransmitting 

 184-188 lUH-eivina- 



Thus only two basic kinds of paired chainiel band filters are rcfiuired, 

 I'ather than four kinds. In these filters, as well as the reversible giou}) 

 filters, the filter d(\signations are so arranged that when the filter is in 

 l)laoe the propel- filter designation is in view. 



Twin Channd Unit 



The twin chaimel unit is shown in somewhat more detail in Fig. 10. 

 There are two kinds of twin channel units to serve the foiu* channel assign- 

 ments, and the freciuencies shown on Fig. 10 correspond to those shown 

 on Fig. 8. (and Fig. 9). A transmitting carrier adjustment permits the 

 transmitted carrier level to be set properly in relation to the sideband 

 levels. In order that the group regulators may function primarily on 

 the carrier, and thus be substantially independent of voice or signaling 

 sidebands, the carrier is transmitted approximately 6 db above the side- 

 band level. 



On the receiving side of the twin channel unit a regulating amplifier 

 controls the received le^'el of both sidebands. It does this from the carrier 



LINE FREQUENCIES IN KILOCYCLES 

 FOR EACH CHANNEL 



4 CHANNEL TERMINAL GROUP 



FREQUENCIES IN KILOCYCLES 



FOR EACH CHANNEL 



LOW 

 GROUP 



12 3 4 



236 



GROUP 



CARRIER 



HIGH 

 GROUP 



60 



I 



Ll. 



256 

 GROUP 

 CARRIER 



4 3 2 1 



Fig. 9 — Type-OB system frequencies. 



