492 



BELL SYSTEM TECHNICAL JOURNAL 



TABLE III 



Artificial Line Constants (Fig. 20) 



(5.0-15.4 kilocycles per second) 



Iterative Impedance R = 605 ohms. 



A structure suitable for a base attenuation equalizer is that of Fig. 

 21, transformed from Network 11, Appendix IV. In designing it to 

 simulate the required attenuation characteristic shown, the procedure 



2Z 

 20 

 W 

 W 



i" 



I 10 



Z 4 6 8 10 12 14 /6 



Frequency (kolocycles per second) 



Fig. 21 — Base attenuation equalizer and its attenuation characteristic for carrier 



telephone circuits. 



was first to choose arbitrarily a plausible maximum attenuation for the 

 network and then to use in the attenuation linear equations the three 

 desired attenuation values at the mean and the extreme frequencies 

 of the frequency range. At the highest frequency the attenuation 

 was lowered slightly to allow for coil dissipation. Several such com- 

 putations were made with different values of this maximum until a 

 network was derived which gave a satisfactory result at all frequencies 



