The IEC-835 Phaselcon measures the subcarrier to horizontal condition of any composite NTSC video signal and displays the results on any standard monitor. This measurement system also greatly decreases the time involved in extremely precise system timing. The information shown on the video monitor is horizontal timing and subcarrier phase. The visual display of the Phaselcon is keyed over the selected input. The Phaselcon displays the graphics for SC/H in the lower ½ of the video display.
In the certify mode of operation, a sine wave is displayed that represents one cycle of subcarrier. A vertical line represents the leading edge of sync relative to subcarrier phase. In the compare mode of operation, the certify and compare signals are displayed. An additional vertical mark is displayed on the left side of the display that shows relative differences in horizontal timing between the two composite signals. When H phasing reaches 200 nS the vertical line appears on the right for accurate timing.
Although the primary function of the Phaselcon is SC/H certification, it does system timing and burst amplitude as well. Timing of two video sources is accomplished by adjusting the source timing until the two vertical lines on the left side of the display are superimposed. As the source timing approaches 200 nS, the vertical line is moved to the right side of the display to increase the accuracy of the measurement. SC/H is accomplished by adjusting the source subcarrier for a match of the two sine waves. Each source to be matched should be switched into the compare input of the Phaselcon and calibrated until all sources in the system are timed and phased.
The shadow mode of operation reduces the video level behind the sine wave graphics. This area is calibrated to represent 40 IRE units for accurate burst level adjustment. The single sine wave signal should just touch the top and bottom area of the shadow signal. By comparing all video sources in the system, a perfect burst match can be obtained.