On the recording of low frequency signals on magnetic tape
A short review of the different methods of recording on magnetic tape is given together with the advantages and disadvantages of each method. Particular emphasis was given to the ability to record low frequencies. This review is given to verify a particular choice of recording technique, where the signals, in a frequency range from 1-100 cps, are recorded by the direct record method at a tape speed of 0.06 in per sec. The playback is performed on a high quality machine operating at one of the conventional speeds (in this case 7/2 in per sec was chosen). Thus a time compression of 125 times and a frequency multiplication with the same factor are obtained, in addition to a very long recording time. A tape recorder based on these principles has been constructed and details concerning the mechanical and electronic units are given.