Chapter 15: DOCSIS 3.1 Cable Modem Test
To link a PC to the instrument and use the DS2831 as a DOCSIS 3.1 32x8 or OFDM cable modem, connect a
standard Ethernet cable to the LAN port in the DS2831’s top panel. Set the computer network IP settings to
DHCP. The computer can then access the Internet once the Cable Modem has registered with the CMTS.
The DS2831 incorporates an automatic switching Ethernet chip. The DHCP function of the instrument does
not conflict with the DHCP function of an external computer, so the DHCP mode does not need to be
disabled.
There is one exception, however. If the Cable Modem configuration files sent by CMTS include the setting
Maximum_Number_of_CPEs=1
(meaning that the Cable Modem can support only one CPE device), the
DS2831’s DHCP does need to be disabled. This allows the computer to automatically acquire an IP.
15-1 Basic Operation
Before starting a cable modem measurement, ensure that
DHCP
is enabled in the unit’s settings.
If the downstream frequency and upstream channel ID of the bidirectional network are already known,
press
DS Freq
(F4) to preset the priority downstream frequency and upstream channel ID. This helps shorten
registration time dramatically, as the instrument will not have to scan for the DS DOCSIS main channel
frequencies and will instead seek connection at the programmed frequency directly. (See below.)
Users may also set the "Level Correction" value to compensate for inaccuracies. The final result displayed on
the screen will be the measurement result + Level Correction value.
Cable Modem Downstream Frequency Configuration
:
The above icons appear when the Cable Modem function is active. The color of the four dots indicates the
CM status.
Red
: CM is initializing.
White
: CM is registering with the CMTS.
Green
: CM has successfully registered with the CMTS.
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