death_place death_date birth_place nationality fields workplaces signature_alt footnotes birth_date known_for residence signature article_title name alma_mater
morristown , new jersey january 1970 -lrb- aged 82 -rrb- ripon , wisconsin american electrical engineering at & t co , bell labs handwritten `` inventor : o. j. zobel '' . zobel appears on a patent application 's signature in his draughtsmanlike hand as it 20 october 1887 filters , equalisers and matching networks new jersey signature.png otto julius zobel
 otto julius zobel university of wisconsin
otto julius zobel

otto julius zobel -lrb- october 20 , 1887 -- january 1970 -rrb- was an electrical engineer who worked for the american telephone & telegraph company -lrb- at&t -rrb- in the early part of the 20th century .
zobel 's work on filter design was revolutionary and led , in conjunction with the work of john r. carson , to significant commercial advances for at&t in the field of frequency division multiplex -lrb- fdm -rrb- telephone transmissions .
although much of zobel 's work has been superseded by more modern filter designs , it remains the basis of filter theory and his papers are still referenced today .
zobel invented the m-derived filter and the constant-resistance filter , which remains in use .
zobel and carson helped to establish the nature of noise in electric circuits , concluding that -- contrary to mainstream belief -- it is not even theoretically possible to filter out noise entirely and that noise will always be a limiting factor in what is possible to transmit .
thus , they anticipated the later work of claude shannon , who showed how the theoretical information rate of a channel is related to the noise of the channel .
