Record/Replay Performance of a Video Disc-Recorder System

Video recording on a magnetic medium can be optimized using analog-to-bi-level modulation. The video information is contained in the relative spacing between transitions of the bi-level modulation signal. Quality television displays require a signal-to-noise ratio of 40 dB or greater. Experience has shown that the signal-to-noise performance of a video disc recorder system is essentially that established in the replay of the bi-level signal from the disc. As discussed in this report, when the parameters of the head/disc interface are available for “adjustment,” it is important to have a better understanding of the relative effects of each parameter on the overall record/replay operation. By optimizing the record/replay performance of the head/disc combination, the overall system signal-to-noise capabilities are improved. — Information has been derived and combined in this report to provide understanding of the significant parameters and their effect on the overall pulsewidth and bandwidth responses of the system. Factors of magnetic medium thickness, co-ercivity, remanence and self-demagnetization, head-to-medium separation and velocity, head gaplength and write-current risetime have been considered. The effects of these factors on the pulsewidth response of the record/replay channel are used to direct the optimizing of the disc-recorder system performance. Head-to-disc spacing and head gaplength emerge as the present state-of-the-art parameters which contribute most to the determination of the system's pulsewidth and bandwidth responses.

Print ISSN

0361-4573

Published

1970-11

Content type

Original Research

DOI

10.5594/J13579