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BELL SYSTEM TECHNICAL JOURNAL 



arrangements for various circuit conditions. It will he noted that 

 crossfire between a pair of w'ires used for a telephone side circuit is 

 considerably greater than that between wires of a phantom group 

 but not of the same pair. This is in accord with what was brought 

 out above regarding coupling. The receiving-end crossfire is much 

 greater between cable circuits than in the case of open wires, due to 

 the greater mutual cai)acitance and hea\-ier loading. 



Crossfire Current in Per Cent, of Operating Direct-Current 

 For Average Repeater Sections 



It is practicable to reduce the crossfire to 10 or 20 per cent, of 

 the original value by means of the arrangements which have been 

 described. This has improved considerably the operation of some 

 circuits and made available others which were unsuitable for use. 

 By improving transmission so as to avoid the use of intermediate 

 telegraph repeaters material savings have been effected in certain 

 cases. 



The neutralizing apparatus has no material effect on the quality 

 of telegraph transmission obtained when crossfire is not present, 

 that is, with the parallel wires idle; the application of them, however, 

 reduces greatly the detrimental effect of crossfire on transmission. 

 For example, the use of these arrangements on certain long open-wire 

 circuits makes possible fast manual full-duplex (two-way) operation 

 where only medium-speed half-duplex (one-way) operation was possible 

 before. Furthermore, in the case of some cable circuits where it was 

 previously impossible to operate more than two telegraph circuits 

 per group of four wires, it is now practicable to obtain four telegraph 

 circuits per quad. 



Due to reduction of crossfire, it is usually possible to secure a much 

 better duplex balance after the neutralizers have been applied. The 

 application of anti-crossfire condensers however requires that a some- 

 what different setting of the duplex artificial line be obtained for the 

 best balance, since the extra connection has appreciable admittance 

 to ground. 



