Specifications

Chapter 15 155
Concepts
Trigger Concepts
Concepts
• Field
A television image or frame is composed of 525 (or 625 lines)
delivered in two successive fields of 262.5 (or 312.5 lines) interlaced
together on a CRT when displayed.
When
Field is set to Entire Frame, the line count starts at line one in
field one (often referred to as the “odd field”) and ends at 525 (or 625)
in field two (often referred to as the “even field”).
When
Field is set to Field One or Field Two, the line count begins at “1”
with the first full line in the selected field and ends at count 263 (or
313) for Field One, and 262 (or 312) for Field Two.
•
Sync
Analog broadcast or cable television signals are usually amplitude
modulated on an RF carrier. For NTSC and PAL broadcasts,
typically the RF carrier amplitude is maximized at the sync tips of
the baseband video waveform and minimized at the “white” level.
This results in a demodulated waveform on the analyzer where the
sync pulses are on top, or positive (
Sync (Pos)).
With SECAM broadcasts, typically the RF carrier amplitude is
minimized at the sync tips of the video waveform and maximized at
the “white” level. This results in a waveform on the analyzer where
the sync pulses are at the bottom, or negative (
Sync (Neg)).
A normal baseband video waveform for all TV standards will have
the sync tips on the bottom. When
TV Source is set to Ext Video In,
Sync should be set to Neg.
•
TV Monitor
When TV Monitor is pressed, the picture represented by the video
waveform selected with
TV Source is presented on the LCD display of
the analyzer. The picture can only be viewed, not printed or saved.
Pressing a key that normally brings up a menu restores the original
graphical display with the selected menu enabled.
SECAM 625 50 Hz SECAM 4.406 MHz,
4.250 MHz
Table 15-5
TV Standard Number of
Lines per
Frame
Approximate
Field Rate
Color
Encoding
Method
Color
Subcarrier
Frequency