Tektronix 013-0278-XX, Инструкция по эксплуатации, Страница: 12 / 32

The Video Display Clamp
2
013-0278-00 Video Display Clamp
Video Signal Disrupted with 60 Hz Hum Video Signal Stabilized using the Video Display Clamp
Figure 2: Video waveform disrupted by 60 Hz hum
The Video Display Clamp receives its power from the host instrument. The host
instrument must have a TEKPROBE
TM
Level 2 interface (such as the Tektronix
TDS400, TDS500, and TDS600 Series Oscilloscopes).
The video display clamp works with most popular signal formats including the
following:
H
NTSC
H
PAL
H
HDTV (component and composite)
Features
Features of the video display clamp (other than setting the back porch to ground
reference) include the following items.
CLAMP FILTER. When ON , the Video Display Clamp ignores the presence of a
color burst signal. This helps ensure a ground level for the back porch. The filter
does not remove the color burst signal from the video waveform.
SYNC POLARITY.
Select + to match sync pulses having a positive leading edge.
Select -- to match sync pulses having a negative leading edge.
Using the video display clamp
Signals passing through cables often pick up stray 60 Hz hum (from the line
voltage) or a small DC offset might be generated by the video equipment.
Although these signals may not affect the quality of the information contained in