Test signals and test signal generators for use with PAL plus televisions
AssigneeFluke Corporation
InventorsRene Vroemen, Rolf Putzhofen
Life of this patent
Estimating the term…
Abstract
A test pattern is suitable for a television signal decoder which detects changes in the color content of a signal from frame to frame, and on the basis of these changes attenuates high frequency luminance components, and possibly switches its output between intra-frame averaged chrominance and high-frequency luminance signals and directly-derived signals. The test pattern has discrete areas within which a motion value representing the change in chrominance from frame to frame is constant, but different from the value in other areas. The areas also contain a high-frequency luminance component. Other areas have a hue which varies from field to field.
Claims16
A test signal provided at the output terminal of a signal generator for testing a television signal decoder which decodes a television signal by attenuating high frequency luminance components in dependence on detected changes, with respect to time, in the chrominance content of elements of a picture defined by the signal, the test signal containing a high frequency luminance component, and defining picture areas each containing a plurality of cycles of said high frequency luminance component and each having a chrominance content which varies with respect to time at a rate which is constant within the area but different from rates in other areas.
A test signal provided at the output terminal of a signal generator for testing a television signal decoder which decodes a television signal by attenuating high frequency luminance components in dependence on detected changes, with respect to time, in the chrominance content of the signal, the test signal containing a high frequency luminance component and defining a picture region throughout which one of two chrominance signals defining said chrominance content varies with respect to time at different rates, the other chrominance signal being constant throughout that region.
A signal generator for testing a television signal decoder which decodes a television signal by attenuating high frequency luminance components in dependence on detected changes, with respect to time, in the chrominance content of elements of a picture defined by the signal, the signal generator being operable to generate a test signal containing a high frequency luminance component, and defining picture areas each containing a plurality of cycles of said high frequency luminance component and each having a chrominance content which varies with respect to time at a rate which is constant within the area but different from the rates in other areas.
A memory storing data defining two frames of a test pattern for testing a television signal decoder which decodes a television signal by attenuating high frequency luminance components in dependence on detected changes, with respect to time, in the chrominance content of elements of a picture defined by the signal;
- the test pattern having picture areas each containing a plurality of cycles of a high frequency luminance component and each having a chrominance content which varies from frame to frame by an amount which is different from the amounts in the other areas.
A method of testing a television signal decoder which decodes a television signal by attenuating high frequency luminance components in dependence on detected changes, with respect to time, in the chrominance content of elements of a picture defined by the signal, the method comprising:
- (a) applying to the decoder a test signal containing a high frequency luminance component, and defining picture areas each containing a plurality of cycles of said high frequency luminance component and each having a chrominance content which varies with respect to time at a rate which is constant within the area but different from the rates in other areas;
- (b) observing a picture generated by an output of the decoder;
- and
- (c) determining whether the decoder is attenuating the high frequency luminance component by inspection of the picture to determine differences between the visibility of the high frequency component in respective areas .
Dependencies are inferred from the claim text.