A novel method of measuring the deviation of video FM modulators

The author presents a simple yet accurate method of verifying, and if necessary adjusting, the frequency deviation of the visual carrier and of the aural subcarriers without having to resort to the indirect method of carrier Bessel null. The method proposed is a direct method in that it measures the actual deviation of the FM carrier when this carrier is modulated with video test signals. This assures optimum use of the available transponder bandwidth for single or dual video operation. Tables and charts are provided for determining the levels of test tones for any frequency deviation of the main carrier or aural subcarrier.<>