CIRCUIT ARRANGEMENT FOR CIRCUIT GENERATION AND CIRCUIT CENTERING IN AN ELECTRONICALLY GENERATED GRID TEST PATTERN.

摘要

1. Circuit arrangement for generating a circle in an electronically generated grating test pattern, particularly for different television line standards and vertical frequencies, the video pulses for the circle being generated by double integration in each case from a rectangular voltage by means of a vertical-and a horizontal-frequency parabolic voltage and the parabolic voltage having a constant crest voltage as a quadratic function of time and a second null which can be changed by changing the time constant, characterized in that the resistors used in the integration sections are connected in series with one electronic switch each in such a manner that, for changing the time constant, the switch is switched at a frequency which is higher compared with the repetition frequency of the parabolic and at a variable duty ratio which depends on the required time constant and by this means the effective value of the resistors determining the integration is changed.