Modulator Calibrator for Helical-Scan Videotape Recorders

Determining that modulator frequencies for helical-scan videotape recorders were at least close to manufacturer's specifications required the time-consuming use of a calibrated oscilloscope and frequency generator until the use of integrated circuits made it possible to design and construct a simple, inexpensive device to calibrate the modulator. Once installed in the recorder the calibrator may be utilized to check and adjust the modulator prior to recording. The result is less time spent in preparing recorders for use and reduction of the possibility of over-modulation. Additionally, the use of the modulator calibrator decreases color moiré, and sideband noise, increases frequency response and results in a reduction in differential gain and phase errors. The use of this calibrator requires only the monitoring of the video output of the recorder with any waveform monitor or even an uncalibrated service scope.

Print ISSN

0361-4573

Published

1972-09

Content type

Original Research

DOI

10.5594/J08227