. The Bell System technical journal . are required to tolerate a lengthen-ing or shortening of the front end of any current impulse of at least40 per cent of its length and with the same adjustment a lengtheningor shortening of the rear portion of any current impulse of at least 35per cent with the start pulse undistorted. Since bias is nearly alwayspresent to some degree in the received signals, and since as interpretedby the receiving distributor it affects only the front end of the currentimpulses as illustrated in traces (b), (c), (d) and (e) of Fig. 5, the 628 BELL SYSTEM TECHNICAL JOURNA
. The Bell System technical journal . are required to tolerate a lengthen-ing or shortening of the front end of any current impulse of at least40 per cent of its length and with the same adjustment a lengtheningor shortening of the rear portion of any current impulse of at least 35per cent with the start pulse undistorted. Since bias is nearly alwayspresent to some degree in the received signals, and since as interpretedby the receiving distributor it affects only the front end of the currentimpulses as illustrated in traces (b), (c), (d) and (e) of Fig. 5, the 628 BELL SYSTEM TECHNICAL JOURNAL distributors are usually adjusted for maximum tolerance of front enddistortions and then have ample tolerance for such distortions of therear ends of the current impulses as are experienced under serviceconditions. Regenerative Repeaters As circuits become longer and more complex, eventually a pointis reached beyond which signal distortion becomes so great that thesignals cannot be reliably received without error. To overcome this. Fig. 6—Regenerator unit. limitation a device known as a regenerative repeater may be insertedin the line at this point. It has a receiving mechanism similar inprinciple to the receiving distributor of a teletypewriter and willaccurately receive and interpret any signals which a teletypewriterwould accurately record. This receiving mechanism is interconnectedwith a retransmitting mechanism, or sending distributor, which re-transmits the signals reshaped and reformed so as to be substantiallyfree from distortion. In its latest form a one-way regenerative re-peater consists of a receiving magnet and a set of transmitting contactsinterconnected by some relatively simple mechanical parts driven from FUNDAMENTALS OF TELETYPEWRITERS 629 a motor. A photograph of such a recently developed regenerativerepeater unit is reproduced in Fig. 6. By means of these regenerative repeaters reliable teletypewriterservice may be extended to any desired distances so lo
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
