Self- Timing Regenerative Repeaters 



By E. D. SUNDE 



(Manuscript received March 29, 1956) 



In self-timing regenerative repeaters, a timing wave for control in pulse 

 regeneration is derived from the binary pulse train at each repeater with the 

 aid of a resonant circuit tuned to the pulse repetition frequency. The timing 

 wave can he made to exercise complete control in retiming of pulses inde- 

 pendent of the received pidse train, or it can he comhined with the received 

 pulse train to provide partial retiming. The timing principles are discussed 

 here for a particular type of self-timed regenerative repeater invented by 

 I Wrathall, in which a timing wave derived from either the received or the re- 

 I generated pulse train is comhined in a particular way with the received pulse 

 train. The regeneration characteristics of such repeaters as determined by 

 various design parameters are investigated, together with the cumidation 

 of timing deviations in repeater chains and the circuit requirements that 

 must be met to insure satisfactory performance. 



INTRODUCTION 



Pulse transmission systems employing binary codes, such as PCM, 

 have two inherent properties that are desirable from the standpoint of 

 avoiding excessive transmission impairments by noise and other imper- 

 fections in the transmission medium. For one thing binary pulse codes 

 permit substantial transmission distortion of pulses within certain 

 tolerable limits with negligible degradation of received signals. For 

 another, regenerative repeaters can be used at intervals along a route to 

 prevent accumulation of transmission distortion of pulses from various 

 sources, so that virtually the entire allowable distortion can be permitted 

 in each link or repeater section. 



The above desirable properties are secured in exchange for increased 

 channel bandwidth, and can be used to full advantage in applications of 

 binary pulse systems to such transmission media as radio and wave 

 guides, where transmission is at such high frequencies that increased 

 channel bandwidth does not entail increased attenuation. In wire cir- 

 cuits, however, where baseband transmission is the more economical 



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