Ripple Measurement Mode - Planar IT-14 Operating Manual

each time, signal is appeared on the input. It is shown by the progress indicator «channels scanning». The
modulation type of the channel indicated by the marker will be shown in position 6 while the measurement is
being performed.
If one of the channel plans has been selected, the scanning will be performed only over the selected
plan channels. In this case, after entering SCAN mode you will see selected channel plan name indicated by
«Plan:» for a few seconds. The navigation by ◄ and ► keys will be fulfilled only within the selected channel
plan. The channel name will be displayed in position 3, modulation type will be displayed in position 6.
In SCAN mode the Analyzer applies estimating method for determining the digital channel level. This
method involves measurement of the signal level in the central point of the channel, which is further
recalculated into channel level value using the following formula:
Uch = Um +10Lg (Вch/Вm) + К, where
Uch - channel level;
Um – channel level in the central point;
Вch - digital channel bandwidth;
Вm – measurement channel passband;
К - correction coefficient.
The value of the Bch bandwidth is determined by the channel plan (Section 4.4.2) or by channel
template (Section 4.9.6 ), if no channel plan has been selected. The K constant are determined empirically.
This method helps to accelerate the measurement process but gives additional error when digital
channel has high ripple.
The graph reference level shown in Figure 4.3.8 is automatically set to the channel with the maximum
level.
You can access other measurement modes using functional keys. F1 key will open LEVEL measurement
mode (Section 4.3.2). F2 key will open RIPPLE measurement mode (Section 4.3.4). F3 key will open
SPECTRUM measurement mode (Section 4.3.5).

4.3.4 RIPPLE measurement mode

This measurement mode is selected from SCAN mode by pressing F2 key. This mode displays signal
levels as vertical bars and the horisontal level lines between the peaks of the two selected channels. The
screen view is represented in the Figure 4.3.9:
On the screen you will see the following data:
1 – channels ripple value between A and B markers
2 – A marker
3 – command line with commands activated by F1, F2 and F3 keys
4 – B marker
Adjust the marker position by ◄ and ► arrows. Selection of the marker is performed by F1 and F3 keys
and indicated by the asterisk in the command line.
If no channel plan is selected, all the channels of the channel template will be displayed on the screen.
Channel modulation type is determined automatically each time, signal is appeared on the input and what is
shown by the progress indicator (channels scanning).
If one of the channel plans has been selected, the scanning will be performed only over the selected
plan channels. The navigation by ◄ and ► keys will be fulfilled only within the selected channel plan.
The graph reference level shown in Figure 4.3.9 is automatically set to the channel with the maximum
level. The marker positions are saved into the memory and restore once you enter RIPPLE measurement
mode again.
Channels measurement nad representation on the graph according to the same principle as in SCAN
measurement mode (Section 4.3.3).
Figure 4.3.9
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