424 BELL SYSTEM TECHNICAL JOURNAL 



and /, by a pulse of approximately equal amplitude and opposite 

 polarity in the vibrating winding and the position of the relay armature 

 will therefore remain unchanged. Thus as the relay is actually 

 operated by the energy supplied by the locally generated vibrating 

 impulses and the received signalling current is employed only to 

 neutralize the effect of the vibrating impulses during the second and 

 succeeding time units of the sustained pulses, a considerable amount of 

 distortion may be present in the signals without causing errors in 

 reception, in fact the impulses of unit length may be entirely missing 

 without interfering in any way with the accuracy of reception. 



Ordinary polarized relays not provided with the vibrating feature 

 are operated by the energy supplied by the amplified signals, which 

 must consequently be quite free from distortion in order to insure 

 faithful reproduction of the transmitted signal. The speed of trans- 

 mission on long submarine cables employing non-vibrating relay 

 reception cannot exceed that frequency at which the received signalling 

 impulses of unit length are reduced by the attenuation of the cable 

 to an amplitude which is only enough greater than the interference 

 currents present to cause positive operation of the relay. The 

 vibrating relay, however, does not require the pulses of unit length 

 to be present at all, so that its limiting speed is that at which the 

 impulses of two units length are received in just sufficiently large 

 amplitude to prevent the relay from vibrating and allow a reasonable 

 margin for overcoming the effects of any interference currents that 

 may be present. This limiting speed is approximately double that 

 obtainable with the use of non-vibrating relays. 



