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BELL SYSTEM TECHNICAL JOURNAL 



(The neutralizinj^ impulse is indicated by the dotted arrows.) An- 

 other point of view is that a symmetrical or balanced arrangement 

 similar to a Wheatstone bridge is provided in which the coupling 

 of the line circuits is balanced by the coupling introduced between 

 the artificial lines. It has been found experimentally that a simple 

 connection consisting of a condenser and a timing resistance in series 

 as shown are sufficient to effect neutralization on either open-wire 

 or cable circuits. It will, of course, be seen that such a connection 

 is effective for neutralizing crossfire from either circuit into the other, 

 and furthermore that it is capable of performing both functions 

 simultaneously. 



As shown in Fig. 4 the neutralizing connection is made at the 

 beginning of the artificial line (at the junction of it and the composite 

 balancing set). This is a convenient point and has been found sat- 

 isfactory for the purpose. 



Fig. 5 — Method of neutralizing receiving-end crossfire between two telegraph circuits 



Condenser arrangements have been in use in this country and 

 abroad for some years in various ways for neutralizing sending-end 

 crossfire on both land lines and short submarine cables. 



Receiving- end Crossfire 



For neutralizing receiving-end crossfire use is made of special 

 connections at the sending end. The method consists in impressing 

 a neutralizing impulse on the disturbed circuit at the sending station, 

 in such manner as not to affect incoming signals at that station, 

 (that is, it does not introduce sending-end crossfire) ; the neutralizing 

 impulse will then travel along the interfered-with circuit so as to 

 arrive at the distant station at the time when the crossfire impulse 

 appears at that station. 



The operation of the receiving-end crossfire neutralizing apparatus 

 will be made clear by reference to Fig. 5, in which the heavy arrows 



