THE L3 SYSTEM — EQUALIZATION AND REGULATION 865 



example, the pilot amplifier is in the beta circuit and therefore must be a 

 highly stable device. On the other hand, the dc amplifier is in the /x 

 circuit and its drifts are reduced by the loop feedback. 



Having developed the feedback nature of the structure and the roles 

 of the components, the conventional feedback art can be used for the 

 analysis of the individual regulator. One can show that : 



Change in output pilot level 1 



Change in input pilot level 1 — Mi^ 



(23) 



System gain change to pilot frequency _ n^ . . 



Change in input pilot level 1 — Mi3 



This result is not very surprising but it can be used to determine the 

 performance of the following regulators in a chain. Many different cases 

 must be considered. Sometimes the pilot levels change because of an 

 effect distributed all along the system. In other cases the change occurs 

 only at the input to the line. Sometimes the pilot level changes are the 

 important effect. In other cases the importance resides in the gain 

 change to the signals. In all cases the results may be complicated by the 

 fact that fjL0 is, in general, a complex number and thus phase as well as 

 amplitude is important. 



Adopting the notation : 

 APin = fractional change in input pilot at nth regulator, 

 APon = fractional change in output pilot at nth regulator, 

 AGn = gain change to signals (near pilot frequency) of nth regulator, 



and 

 AGt = total system gain change =^ Gm 

 one can readily show the following : 

 Case I — Disturbance of pilot only at input to system : 



APqU 



~ap7i 





fe ^ = f^-Y - 1 



f APu \l - y?) 



Case 2 — Equal gain change in each regulating section. 

 \ APc = fractional gain change of section 



(27) 



APo„ 



« = 1 \( ^ X _ l] (28) 



