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Chapter 7 - TV Measuring Range
106 V3.2
You can select the modulation scheme for the DOCSIS variant in another menu.
Figure 7-8 DOCSIS modulation type
The associated symbol rate is automatically set.
Automatic scan with DOCSIS:
If you enter a new channel, the receiver attempts to synchronize with the current settings (DOCSIS
variants, modulation schemes). If this is not successful, the instrument alternatively uses the other
settings
EUDOC64
,
EUDOC256
,
USDOC64
or
USDOC256
to receive the signal that is present.
DOCSIS parameters
7.2.2.2.1
As soon as the receiver has completed the synchronization process, several parameters are shown
on the display. When LOCK appears, it means that the digital receiver is receiving a valid data
stream.
In contrast, UNLK means that either the quality of the signal that is present is insufficient, or that
the parameters of the receiver do not agree, or that no DOCSIS signal can be received at this
frequency.
Once the receiver has synchronized, the set modulation scheme and the associated symbol rate is
shown on the display.
In the case of a US-DOCSIS signal, the automatically detected de-interleaver depths are also
shown in the display. The variable de-interleaver is part of the J83B specification (in the case of
DVB-C and EURO-DOCSIS, the de-interleaver is fixed with I = 12 / J = 17).
