Cable TV Measurements (Option K20) R&S FSL
1300.2519.12 2.88 E-11
Quiet Line: Some measurements need a horizontal line with no video information in it. You must
s
pecify the number of this horizontal line here. For further information see also Example: Creating a
channel table.
Sideband Position: Is the signal in normal position or inverted?
S
ometimes the analog TV signal to be analyzed is only available with an inverted sideband. This
can for example happen if the cable operator feds – for some reason – an inverted signal into the
network. It may also happen in R&D labs where measurements on different IF stages of a new TV
transmitter or a receiver hardware are to be performed. Please be aware, that these two
applications also lead to two different cases when measuring with the Cable TV Measurements
option:
Measurements with channel tables
Measurements without a channel table, i.e. < none >.
The sideband position can either be altered in the modulation standard or in the Analog TV
settings dialog box. When measuring with a channel table, switching the sideband position (from
normal to inverse or vice versa) keeps the channel's start and stop frequencies constant. As a
consequence the RF frequency will be modified.
Example:
Channel Information:
RF frequency = 401.25 MHz
Width = 8 MHz
Modulation standard = analog TV with sideband position = normal.
This leads to the following channel borders:
Start frequency = RF – 1.25 MHz = 400 MHz
Stop frequency = Start frequency + Width = 408 MHz.
Next, the sideband position of the referenced modulation standard will be set to inverse. In order
to keep the start and stop frequencies constant the RF frequency will be adapted as follows:
RF frequency = Stop frequency – 1.25 MHz = 206.75 MHz.
In case of measurements without a channel table, i.e. < none >, we realize that there are no start
and stop frequencies existing. Hence, changing the sideband position keeps the RF frequency
constant. As a consequence you will analyze different parts of the spectrum depending on the
selected sideband position.
Digital TV modulation standards
In the Cable TV Measurements option, digital TV is used as a synonym for quadrature amplitude
modulated (QAM) signals. In digital Cable TV networks exclusively single carrier modulated signals are
used. The Cable TV Measurements option does not support multicarrier techniques such as OFDM in
terrestrial TV networks.
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