Abstracts of Technical Articles by Bell System Authors 



I'ltra-Short-Wavc Receiver for the Cape Charles-Norfolk Multiplex Radio- 

 telephone Circuit} D. M. Black, G. Rodwin and W. T. Wintringham. 

 The requirements for an ultra-short-wave receiver for use in a multiplex 

 radiotelephone link circuit are outlined. The technical details of a receiver 

 designed to meet such requirements in the circuit between Cape Charles 

 and Norfolk, Virginia, are described. 



lltra-Short-Wave Multiplex.- Charles R. Burrows and Alfred 

 Decino. The technical requirements of a twelve-channel ultra-short-wave 

 multiplex system are discussed and the means of meeting them are described. 

 The intermodulation between channels in equipment based on this design 

 has been reduced to the point where it is possible to use twelve-channel 

 radio systems in the toll plant. By employing a sufi&cient amount of en- 

 velope feedback, the transmitter can be operated with a high modulation 

 factor without the use of spread sidebands. 



Airplane Vibration Reproducer? G. R. Crane. This paper describes 

 a reproducer set designed for use in the reproduction for analysis of multiple 

 track film recordings. It is capable of reproducing simultaneously 13 

 variable-area tracks recorded side by side on standard 35-mm. film. Re- 

 corded signals between 5 and 3000 cps are accurately reproduced and may 

 be analyzed for frequency components, amplitude, and phase relation. 



Airplane Vibration Recorder} J. C. Davidson and G. R. Crane. This 

 paper describes a portable film recorder capable of simultaneously recording 

 13 variable-area tracks on 35-mm. film. It is intended for use in the analy- 

 sis of airplane vibration or similar studies in which it is desirable to record 

 disturbances (mechanical, acoustical, or electrical) from a number of sources 

 in such a manner that the resultant record can be analyzed for frequency, 

 amplitude, and phase relation. Film speeds of 12, 6, or 3 in. per sec. are 

 available. 



Application of Sound Recording Techniques to Airplane Vibration Anal- 

 ysis} J. G. Frayne and J. C. Davidson. This paper describes methods 

 which have been developed for analysis of the various vibration components 

 present in airplane structures. The complex wave forms are recorded on 

 standard motion picture sound negatives during flight. These films later, 



^Proc. I. R. E., Fehruarv 1945. 

 ^Proc. I. R. £., February 1945. 

 ^Joiir. S. M. P. E., January 1945. 

 ^Jo'ur. S. M. P. E., January 1945. 

 ^Jour. S. M. P. E., January 1945. 



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