Specifications

154 Chapter 15
Concepts
Trigger Concepts
Concepts
TV Trigger
TV Trigger Setup Menu Functions
•
TV Source
When TV Source is set to SA, the analyzer demodulates the TV
signal, by using the analyzer as a fixed tuned receiver. This allows
stable, zero span sweeps of the baseband video waveform (band
limited by the RBW and VBW filters).
When
TV Source is set to EXT VIDEO IN, an external baseband video
signal may be used to produce the TV line trigger. In this case, an
external TV tuner can be used to obtain the baseband waveform of
the given RF carrier for triggering the analyzer sweep. This will
allow the analyzer to be used in swept mode for measurements of the
RF spectrum to synchronize to the video modulation. The
EXT VIDEO
IN
connector is located on the rear panel of the analyzer.
•
TV Standard
Selection of a TV standard establishes the number of TV lines and
the kind of color encoding method that is used. The number of TV
lines establishes the defaults for the TV line counting circuits of the
analyzer and the color encoding method is used to properly set up
the TV picture display circuits. Option B7B supports both 525 line
and 625 line systems and can provide a color TV picture output for
NTSC and PAL color encoding methods. A black and white picture is
provided for the SECAM method.
The ability to display a color picture is limited by the bandwidth
settings of the analyzer (resolution bandwidth and video
bandwidth). However, baseband video signals input to the EXT
VIDEO IN connector on the rear panel of the analyzer are minimally
filtered, allowing a full color display of NTSC or PAL TV signals.
Table 15-5
TV Standard Number of
Lines per
Frame
Approximate
Field Rate
Color
Encoding
Method
Color
Subcarrier
Frequency
NTSC-M 525 60 Hz NTSC 3.58 MHz
NTSC-Japan
(no pedestal)
525 60 Hz NTSC 3.58 MHz
PAL-M 525 60 Hz PAL 4.43 MHz
PAL-B,D,G,H,I 625 50 Hz PAL 4.43 MHz
PAL-N 625 50 Hz PAL 4.43 MHz
PAL-N
Combination
625 50 Hz PAL 3.58 MHz