EXPERIMENTAL TRANSVERSAL EQUALIZER FOR TD-2 



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DRIVE IN DECIBELS ABOVE NORMAL 



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Fig. 16 — Effect of improved equalization on cross modulation noise, Denver- 

 Omaha route. Measurements on two channels, referred to — 9 db transmission 

 level. 



provement at normal drive, and a somewhat greater improvement at 

 higher dri\'es. Channel B, however, showed a slight degradation at 

 normal drive, which becomes a 9- or 10-db improvement at high drive. 

 In the case of the latter channel, the improvement at normal drive was 

 limited by the presence of a delay ripple, due to waveguide echoes, 

 which was of too short a period to be equalized by the present ecfualizer. 

 The realization of such improvements in a working system is limited 

 by such Avaveguide echoes, which are not stable enough for ready equal- 

 ization, as well as by other instabilities in the transmission characteristic 

 which have been attributed to antenna and air path effects. 



ACKNOWLEDGMENTS 



Several of the authors' colleagues contributed materially to this de- 

 velopment. C. H. Dagnall developed the 315 and 319 type equahzers. 

 A. H. Volz and J. K. Werner developed the coaxial rheo.stat, based on 

 suggestions by S. Bobis. Mrs. Grace L. Ebbe was responsible for much 

 of the equalizer design and the assembly and testing of models. J. G. 

 Chaffee and I. Welber directed the field tests. 



REFERENCES 



1. A. A. Roetken, K. D. Smith, and R. W. Friis, The TD-2 System, B.S.T.J., 30, 

 pp. 1041-1077, Oct., 1951. 



