TYI'K-O CATUUKIi SVSTKM 



70/ 



4 



06 1.2 



FREQUENCY 



Fig. 15 — Net loss frequency charactieristic. 



1,6 2.0 2.4 2.8 



IN KILOCYCLES PER SECOND 



upper and lower sideband filters. In addition, O has transmitting band 

 filters while N does not. 



A situation is of interest which applies to both N and O, as well as 

 to any other system employing the type of compandor controlled from 

 the voice energy. Different frequency characteristics will be obtained 

 with the compandor operating and with the compandor controls locked. 

 Neither of these necessarily corresponds to the operating condition with 

 speech or music. With the compandor controls free and using single 

 frequency test tone, the characteristic obtained is a combination of the 

 freciuency characteristics of the line and control circuits. With the con- 

 trols locked, the characteristic is that of the line only. If the control 

 circuit is substantially flat, there will be little distinction between the 

 measurements. The curve of Fig. 15 is of the type obtained with free 

 controls and with a substantially flat control circuit. 



A typical overall channel load characteristic is shown on Fig. 16. This 

 characteristic includes not only the load curve of various amplifiers, 

 modulators, etc., but shows also the order of match of the compressor 

 and expandor load characteristics. This is a match of curves ha\'ing 

 2:1 slopes on a db basis over a v\ide range of volumes. 



A typical overall net loss variation for a non-repeatered circuit is 

 shoA\Ti on Fig. 17. Principally because of the line regulator in the group 

 receiving units (Fig. 18) a wide range of line loss is covered. A similar 

 regulator is included in each repeater, and the extension of a system 



