R&S FSL Cable TV Measurements (Option K20)
1300.2519.12 2.89 E-11
Fig. 2-63 Modulation Standard Options dialog box for digital TV
This section describes the parameters that characterize digital cable TV signals. Refer to section Digital
TV Basics to learn more about digital TV signals. The parameters discussed here can also be modified
(temporarily) in the Digital TV Settings dialog box.
For digital TV the Modulations Standard Options dialog box is structured as follows:
The channel table references modulation standards by their Name. Its name (see Fig. 2-63) should
comprise information about the used constellation and the symbol rate, e.g. "64QAM_6900''.
Here the Signal Type is always set to Digital TV.
Depending on the TV Standard the default values of the parameters below are set. The following
digital TV standards exist:
QAM J.83/A (DVB–C Europe)
QAM J.83/B (US Cable)
QAM J.83/C (Japanese Cable)
The Constellation parameter supports the values below:
4QAM
16QAM
32QAM
64QAM
128QAM
256QAM
512QAM
1024QAM
Fig. 2-64 shows ideal 16QAM and 32QAM constellation diagrams. 4QAM, 16QAM, 64QAM,
256QAM and 1024QAM have a square structure, whereas 32QAM, 128QAM and 512QAM have a
cross structure.
The Symbol Rate and the Roll–off factor of the pulse shaping filter determine the occupied
bandwidth of the digital TV signal. In the Cable TV Measurements option only root raised cosine
filters are supported. The bandwidth can be calculated by the following formula:
OccupiedBandwidth = SymbolRate (1 + RollOff)
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