Test Instruments for Color Television

Abstract

The development of color television has produced some "growing pains" in television system operation. To radiate a satisfactory color TV signal, routine maintenance must include the measurement and adjustment of some characteristics not ordinarily considered for monochrome television. In other cases the accuracy of operation must be considerably better than in the past. This paper describes several test instruments developed to simplify some of these measurements. The first instrument described produces a frequency response test signal. The signal contains the elements necessary for normal operation of clamp circuits so that a rapid check can be made on either a single component or a complete system, including networking facilities. The second instrument was developed primarily for making differential gain and differential phase measurements. It produces a staircase type signal to which sine waves of a selected frequency can be added. The third device is a calibrated phase shifter useful for making accurate phase measurements. The device and a test method are described. This instrument is particularly useful in making precision measurements on system components. The last instrument described is for frequency measurement. The presence of a color subcarrier makes it important to hold accurately the 4.5 mc sound-to-picture separation. The test instrument reads directly the deviation from the correct spacing with an accuracy of a few cycles.