Cisco Broadband Cable Command Reference Guide

cable downstream frequency
cable downstream frequency
Syntax Description
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Cisco Broadband Cable Command Reference Guide
Chapter 2 Cisco Cable Modem Termination System Commands
To note the downstream center frequency for the cable interface line card to reflect the digital carrier
frequency of the downstream radio frequency carrier (the channel) for that downstream port, use the
cable downstream frequency command in cable interface configuration mode. On the Cisco uBR7100
series routers, to unset the downstream frequency and to disable the RF output from the integrated
upconverter, use the no form of this command.
cable downstream frequency down-freq-hz
no cable downstream frequency
Note The no form of this command is supported only on the Cisco uBR-MC5X20 cable interface line card and
on the Cisco uBR7100 series universal broadband router.
Defaults Disabled. On the Cisco uBR7100 series routers, the default downstream center frequency for the
integrated upconverter is 500 MHz.
Command Modes Interface configuration (cable interface only)
Command History
down-freq-hz The known center frequency of the downstream carrier in Hz (the valid
range is 54,000,000 to 858,000,000). The Cisco IOS supports a superset of
the DOCSIS standard, which is limited to 88 to 860 MHz (88,000,000 to
860,000,000 Hz). The range of center frequency that is acceptable to a CM is
91,000,000 to 857,000,000 Hz. Setting the frequency to values outside these
limits violates the DOCSIS standards.
Release Modification
11.3 XA This command was introduced to support NTSC/DOCSIS Annex B RF
operation.
12.0(7)XR2, 12.0(8)SC Modified to support PAL/SECAM EuroDOCSIS RF operation.
12.1(2)EC1 Supports both Annex A and Annex B.
12.1(5)EC1 Modified to support the integrated upconverter on the Cisco uBR7100 series
universal broadband router.
12.2(11)CY Support was added for the Cisco uBR-MC5X20 cable interface line card.
Usage Guidelines The downstream frequency of your RF output must be set to match the expected input frequency of your
upconverter. To do this, you enter the fixed center frequency of the downstream channel for the
downstream port. (You can also select a default that does not set a specific fixed value.) The valid range
for a fixed center frequency is 54,000,000 to 858,000,000 Hz. The center frequency is also used to
configure an IF-to-RF upconverter that must be installed in your downstream path.
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