SURFboard Cable Modem Installation Manual
Section 2
Overview
The SURFboard cable modem delivers digital multimedia content in a two-way transmission
system. It provides access to a cable data network, which provides access to the Internet and
World Wide Web.
The SURFboard cable modem is authorized by a cable modem terminations system (CMTS) for
use on the network and automatically configures itself with parameters received from the
CMTS or headend. When the SURFboard cable modem is powered on, it:
! Scans the frequency spectrum to locate the data frequency and automatically locks on to the
channel.
! Searches for a message containing the upstream parameters such as frequency, modulation,
symbol rate, and forward error correction (FEC) format.
! Transmits a message to the CMTS requesting additional information enabling network
connection.
! Establishes Internet Protocol (IP) connectivity using Dynamic Host Configuration Protocol
(DHCP)
! Receives a configuration file using the Trivial File Transfer Protocol (TFTP). This file
contains additional parameters required by the SURFboard cable modem.
! Registers with the CMTS and is authorized to use the network.
Figure 2-1 illustrates the SURFboard cable modem data path:
Figure 2-1
SURFboard cable modem data path
Internet
IF
RF
RF
RF
HFC plant
Upconverter
Client PC
Diplex
filter
CMTS
Network
management
services
Customer premises
equipment
SURFboard
external
cable
modem
The SURFboard cable modem supports 64 QAM and 256 QAM signals that are necessary for the
DOCSIS/Euro-DOCSIS data network. This network carries IP data in standard MPEG-2
packets. The RF downstream receives data at rates up to 38 Mbps (55 Mbps for Euro-DOCSIS)
and the RF upstream transfers data rates of up to 30 Mbps. The actual speeds will vary; speeds
of 30 Mbps are only attainable with A-TDMA or S-CDMA technology.
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