Transistorized Binary Pulse Regenerator 



By L. R. WRATHALL 



(Manuscript received March 14, 1956) 



A stjnple transistorized device has been constructed for amplifying and 

 regenerating binary code signals as they are transmitted over substantial 

 lengths of transmission line. By the use of simple circuitry, means are pro- 

 vided whereby the distortion in the output of one repeater due to low fre- 

 quency cutoff is compensated in the next repeater. Furthermore, the repeater 

 is effectively and simply timed from its own regenerated output. A brief 

 discussion of the theory of the circuit is presented along with measured re- 

 sults and oscillograms showing its performance. The effects of extraneous 

 interference on the production of errors in such a repeater are reported. 

 These results are in substayiiial agreement with theory. 



1. INTRODUCTION 



Long distance communication using digital transmission is not new 

 but was used by man in his earliest communication system. In fact, his 

 first successful electrical system, the telegraph, made use of binary 

 pulse codes. It was not until the invention of the telephone that the 

 emphasis was shifted from the digital to carrier and voice systems. 

 During recent years the development of new electronic devices and 

 techniques have brought digital transmission into the picture again, 

 and it now seems possible to use it not only for telephony but for tele- 

 vision as well. Future systems will probably make use of the binary 

 code, this choice being dictated by circuit simplicity and performance. 



The fundamental requirement for perfect binary transmission is to 

 be able to detect the presence or absence of a pulse in each of a regular 

 set of discrete time intervals. From this requirement the principal ad- 

 vantages of such a system may be tabulated. First, a pulse can be 

 recognized in the presence of large amounts of interference. Second, 

 when a pulse is recognized it can be faithfully regenerated, suppressing 

 the effect of the interfering noise to any desired degree. Third, simple 

 high-efficiency non-linear devices such as multivibrators or blocking 

 oscillators can be used to regenerate the pulses. The great disadvantage, 



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