90 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 19o() 



CONCLUSIONS 



It is possible to build a simple device for regenerating pulses directly 

 at microwave frequencies. A long chain of repeaters employing this 

 regenerator should perform satisfactorily as long as the rms signal-to- 

 noise ratio at each repeater is maintained at a value of 20 db or greater. 

 There are a number of remaining problems which must be solved before 

 we have a complete regenerative repeater. Some of these problems are: 



(1) Recovery of information for retiming from the incoming pulse train; 



(2) Automatic gain or level control to set the slicing level at each re- 

 peater; (3) Simple, reliable, economical, broad-band microwave ampli- 

 fiers. (4) Proper filters — both for transmitting and receiving. Traveling- 

 wave tube development should eventually result in amplifiers which 

 will meet all of the requirements set forth in (3) above. Any improve- 

 ments which can be made in the regenerator without adding undue 

 complications would also be advantageous. 



ACKNOWLEDGMENTS 



A. F. Dietrich assisted in setting up the equipment described here and 

 in many other ways. The experiment would not have been possible with- 

 out traveling-wave tubes and amplifiers which were obtained through 

 the cooperation of M. E. Hines, C. C. Cutler and their associates. I wish 

 to thank W. M. Goodall, and J. R. Pierce for many valuable suggestions. 



