(;.//.v or /ico-ic.;)' iiu.i-.riio\r. nui'i-.-hhns i'» 



follows until it t-ncountiTs the irri'(j;iilarity H-. At Bi it is pari i. illy 

 re tinted, one |X)rti»n returning to the repeater anil the other travel- 

 ing to the terniinal -Ij where it is ahsorlad. The reflected wave 

 passes ihrouuli the refx-ater, is ani[)litux! and iraiisversi-s the line 

 L\ until it encounters the irregularity B\ where it is again reilecied, 

 one iKirt Uing propagated to the terminal At where it is dissipated, 

 while the other part returns to the repeater and repeats the cycU 

 of anipliliration and reflection. This action continues indefinitely 

 the wave being reflected alternately from the irregularities B, and 5|, 



If the total gain in the round trip path is greater than the tcjtal 

 loss the wave will Ix; stronger on each arrival at any point in the 

 circuit than on the preceding trip and will continually increase in 

 power until the power limits of the repeater or some other cause 

 prevents a further increase and a steady sing is established. If the 

 gain is less than the loss, the wave will become weaker with each 

 trip from Bi and B^ and back until it falls below the strength which 

 can be detected. 



KvidentK-. if the repeater gain is made so great that a steady sing 

 is established, satisfactory- telephoning o\cr the circuit will be im- 

 possible. Serious quality impairment ma\- occur, however, when 

 the gain is not so great as this. Consequently, when irregularities 

 are present in a line containing repeaters, the repeater gains are 

 necessarily limited. 



In the above illustration, it was assumed that two irregularities 

 were present. Serious effects, however, due to the production of 

 echo effects which may Ik? heard by the talker, may be produced !)>' 

 reflection from a single irregularity. Consequently, a single irreg- 

 ularity in the circuit will set a limitation on the repeater gain even 

 though it could not cause singing if a 22-type repeater were used. 



Frf)m the foregoing explanation, it is evident that the effect of the 

 reflections at the irregularities, which limits the repeater gains, is 

 not dependent upon any special prof)erties of the telephone repeaters. 

 These limitations will necessarily exist with any types of repeater 

 whatsoever which have the property of producing amplification 

 in lM)th directions at the same time. 



Ki'iKcT oi" IsiNi, Tin: Wkonc; Link Fmpkd.vm r; 



The discussion will now i)e extended to show tiiat not rinly must the 

 lines with which a repeater is to work be smooth, if limitation of the 

 gains is to be avoided, but also the repeaters must be designed to fit 



