VOLUME XXVI JULY, 1947 NO. 3 



THE BELL SYSTEM 



TECHNICAL JOURNAL 



DEVOTED TO THE SCIENTIFIC AND ENGINEERING ASPECTS 

 OF ELECTRICAL COMMUNICATION 



Telephony by Pulse Code Modulation W. M. Goodall 395 



Some Results on Cylindrical Cavity Resonators 



J. P. Kinzer and I. G. Wilson 410 



Precision Measurement of Impedance Mismatches in 

 Waveguide Allen F. Pomeroy 446 



Reflex Oscillators J. R. Pierce and W. G. Shepherd 460 



Abstracts of Technical Articles by Bell System Authors. . 682 



Contributors to This Issue 691 



■*y- 



AMERICAN TELEPHONE AND TELEGRAPH COMPANY 



NEW YORK 



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