TABLE OF CONTENTS The story of video tape recorders really began before the turn of the century with the experiments of Valdemar Poulson. By this time, the relationship between electricity and magnetism was well understood, and the idea of impressing magnetic pulses on a moving magnetic medium was sufficiently advanced in 1900 to justify the US patent on Poulson s apparatus, the Telegraphone. The medium was magnetic wire rather than tape; and without any form of recording bias and scant means of signal amplification, the reproduced sound signal was low, noisy, non-linear and lacking in frequency response. These problems of tape and record/replay head performance are ones that have continually recurred throughout the history of sound and vision tape recording, as we shall see.
By the early 1930s, many advances had been made in the field. The d.c. bias or pre-magnetism of the recording wire had been tried with better results, then overtaken by the superior system of a.c. bias, as used today. The magnetic wire gave way to steel tape 6 mm wide travelling at 1.5 m/s, and performance became comparable with the contemporary disc recording system. Not hi-fi by any means, but certainly adequate! The BBC adopted and improved the Blattnerphone system and in 1932 broadcast a programme of the Economic Conference in Ottawa, for which 7 miles of steel tape was used, edited by means of a hacksaw and soldering iron! This era also saw the first crude forerunner of a servo system in the Marconi ?Stille...
