Experimental HDTV digital VTR with a bit rate of 1 Gbps

This paper describes the technical details of an experimental High Definition Television (HDTV) digital VTR with a bit rate of 1.037 Gbps. The basic parameters, which must be taken into account in designing the record/ playback system of any digital VTR, are the tape and head materials, modulation code, minimum recording wave length and maximum recording frequency. To obtain a short recording wave length, metal particle tape and Sendust sputtered type heads have been used. In order to achieve the longest minimum wave length and the lowest maximum frequency, scrambled NRZ and 8-8 conversion, requiring no overhead, were studied as possible modulation codes. A special multi-channel rotary transformer with an extended frequency response has been newly developed in order to record the video data with 8 heads, and to reproduce with an additional 8 heads. Since the total recording rate is 1.037 Gbps, the recording rate per channel is 130 Mbps. The tape/head interface and channel equalization are also thoroughly investigated. Using this experimental machine, the fundamental feasibility of such an ultra high-speed digital recording has been confirmed. The experimental results and the possibility of a higher recording data rate are discussed.