Tektronix 1740A/1750A PAL, SC/H R---Y

Basic Measurements

PAL

The 1751A uses a series of dots around the compass rose with a single dot in a blanked area to denote sync (see Figure 4-8). Place the burst vector at 0°, align the burst vectors with the graticule markings, and read the SC/H phase error as the amount of sync dot offset from the the horizontal axis. The input signal and the the EXT REF signal are properly color framed when the sync dot is within 90° of the burst vector.

VECTOR PHASE

Figure 4-8. PAL SC/H display.

SC/H R---Y

SC/H phase can be viewed over a frame of video. Select WAVEFORM display and FIELD sweep. Enter the FILTER menu and select SC/H R---Y. For NTSC, stable SC/H is a horizontal line as shown in Figure 4-10. (Figure 4-9 shows the same display with a LINE sweep selected.) A sample SC/H phase error is shown in Figure 4-11. The flat lines indicate that SC/H phase is stable over the entire frame. For PAL, SC/H is a sine wave resulting from the 25 Hz offset (Figure 4-12).

4-12 1740A/1750A Series Waveform/Vector Monitor User Manual