624 THE BELL SYSTEM TECHNICAL JOURNAL, JULY 1951 



This procedure, in practice, requires that the identification equipment be 

 arranged to discriminate against the surges directly introduced on these 

 leads by other equipment connected to them and against crosstalk result- 

 ing from capacitive or magnetic coupling to other leads. This is done in 

 part by adjustment of impedances and by discriminators either at the coding 

 elements or in the common circuits. The problem of feedback has been dis- 

 cussed under Section II. There is no special technical difficulty in this but 

 the economics is important. 



The third general type has no special problems due to large numbers of 

 wires or coding elements or feedback or crosstalk. The economic considera- 

 tions involve the additional equipment in numerous other switching ele- 

 ments to read the switch positions and the fact that, if the switch position 

 does not directly give the wanted number in the desired code form, resort 

 must be made to additional translation. 



Future possibilities lie in new methods avoiding these various problems 

 economically, probably methods with entirely new basic concepts. 



Conclusion 

 General Remarks 



The similarity of the problem of identification to that of translation is 

 obvious. In identification the general problem is to construct an output 

 code for information on an item to which the identifier has a connection. 

 In translation the problem is to construct an output code for information 

 on an item for which the translator has a previously registered code to use 

 as input information. 



Now, if we stretch the point, we could very well say that the identifier, 

 because of its connection to the object being identified, also has an input 

 code when a signal to start identification is applied to this connection, the 

 input code simply being a mark on a one-out-of-X basis. 



What is probably of more importance than the similarity of identifiers 

 and translators is the frequent occurrence in switching networks of elements 

 that functionally or operationally or both are essentially translators or 

 identifiers although they are not so named. 



The ordinary fine relay, responding to the subscriber when he starts a 

 call, can be considered as a coding element in a translator in some simple 

 dial systems, as it translates an input code consisting of a mark on one out 

 of 100 leads to marks in a two-place decimal system used to direct the line 

 finder to the line. In the case of the No. 5 crossbar system, the line relays 

 and their associated group equipments, although not so named, can cer- 

 tainly be considered as a identification system as the end result of their 

 operation is the registration of the calling equipment number in a common 



