Chapter 11 - DOCSIS Analyzer
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11.5.1
Tuning to an OFDM-downstream
With the Menupart
MODULATION -> DOCSIS
in the TV-Range (6.2.2 - DIGITAL (DVB-C,
DOCSIS) operating mode) you can activate the downstream receiver of the measurement device.
Additional the modulation scheme of the DOCSIS-standard can be choosed. Here you will be find
also the
OFDM
variant to the EURO- and US-DOCSIS variants. If
OFDM
is activated, in the upper
menu field "OFDM" is shown. The number next to it is the bandwidth of the carrier in MHz. If the
bandwidth is unknown, a 0 will be indicated.
Another possibility to activate OFDM is the usage of the so called D-channel (user defined, see
Chapter 17.8.1 - D-Channels). In an D-channel the bandwidth indicates an ScQAM or an OFDM
channel. For automatic detection of the standard EU/US-DOCSIS must be predefined, otherwise
the receiver operates always in OFDM mode.
Figure 11-13 activate OFDM standard
With
ENTER
the boot- and lock-process can be started. The progress of the bootprocess (ca. 30
seconds) is shown in a graphic with the percentage value. Depending of the modulation standard,
signal level, signal qualitiy (MER) and the lock-status are also shown. If the bootprocess is finished,
the Mainscreen of the DOCSIS-3.1-Analyzer is shown, with two diagrams for Up- and Downstream.
OFDM Informations can only be evaluated after a complete bootprocess and a first lock to the
OFDM channel. That Information can be shown in Submenu
DOWNSTREAM
.
11.5.2
Down- and Upstream analyze with DOCSIS-3.1-Analyzer
With the DOCSIS-3.1-Analyzer first you can make a statement, if pincipal a communication
between modem and CMTS can be established. Further the Analyzer is an instrument for leveling
back channel amplifiers.
After a successful lock to a CMTS, the DOCSIS-3.1-Analyzer offers a graphical overview of all
bonded Down- and Upstreamchannels with level informations and channel bandwidths. The
ranging process only works in the mainscreen, in the submenues are only the evaluated data
visible.