Set the Downstream Center Frequency

Note The default values for the commands used in these configuration steps are, in most cases, adequate to configure the Cisco uBR7246.

Set the Downstream Center Frequency

You need to set the downstream frequency of your RF output to comply with the expected input frequency of your upconverter. To do this, enter the fixed center frequency of the downstream RF carrier for a downstream port.

Downstream frequency is an information-only command that should reflect the digital carrier frequency, which is the center frequency of the downstream RF carrier (the channel) for that downstream port. The configuration controlling the digital carrier frequency is done in the IF-to-RF upconverter that must be installed in the downstream path from the Cisco uBR7246. Refer to the upconverter’s manufacturer’s instructions for information about configuring the upconverter.

The digital carrier frequency is specified to be the center of a 6.0 MHz channel. For example, EIA channel 95 spans 90.000 to 96.000 MHz. The center frequency is 93.000 MHz, which is the digital carrier frequency that should be configured as the downstream frequency.

Note The digital carrier frequency is not the same as the video carrier frequency. For EIA channel 95, the video carrier frequency is 91.250 MHz, which is 1.75 MHz below the center frequency.

Note This command currently has no effect on external upconverters; it is informational only.

To set the downstream center frequency, use the following command in cable interface configuration mode:

Command

Purpose

cable downstream frequency down-freq-hzEnter the fixed center frequency for your downstream RF carrier in Hz.

Validation Tips

To verify the current value of the center frequency, enter the show controllers cable command for the downstream port that you have just configured:

•If the center frequency is fixed, the actual frequency will be displayed:

router# show controllers cable 6/0 downstream Cable6/0 Downstream is up

Frequency=96000000, Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps

FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4

•If the center frequency is not fixed, the frequency will show that it is not set:

router# show controllers cable 6/0 downstream Cable6/0 Downstream is up

Frequency is not set. Channel Width 6 MHz, 64-QAM, Symbol Rate 5.056941 Msps

FEC ITU-T J.83 Annex B, R/S Interleave I=32, J=4

Configuring Cisco uBR7246 Universal Broadband Router Features VC-139

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Cisco Systems uBR7246 manual Set the Downstream Center Frequency, Command Purpose
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uBR7246 specifications

The Cisco uBR7246 is a versatile edge router designed primarily for cable operators wishing to deliver high-speed Internet, telephony, and video services over hybrid fiber-coaxial (HFC) networks. This router is part of Cisco's extensive line of broadband access solutions, addressing the increasing demand for bandwidth among consumers and businesses alike.

One of the uBR7246's main features is its ability to support a wide range of broadband technologies including DOCSIS (Data Over Cable Service Interface Specification) and EuroDOCSIS. The router is designed to facilitate the delivery of high-speed data services while allowing for flexible configurations that adapt to evolving network technologies. This is crucial for operators looking to maximize their network efficiency and future-proof their infrastructure.

The uBR7246 is equipped with multiple modular slots, enabling service providers to customize the router according to their specific needs. High-capacity interface cards can be added to support various types of connections, such as Ethernet and TDM (Time Division Multiplexing), thus offering scalability. With support for both DOCSIS 1.0 and advanced versions like DOCSIS 3.0 and 3.1, the router can handle increased data rates and offer maximum efficiency in terms of bandwidth utilization.

Security features are integral to the uBR7246, as it employs advanced measures such as encryption and robust authentication protocols to ensure that subscriber data remains secure. This is particularly vital in an era where cyber threats are pervasive, and customer trust is essential.

In terms of performance, the uBR7246 offers exceptional throughput, capable of efficiently managing vast amounts of traffic without degradation of service. Advanced Quality of Service (QoS) mechanisms help prioritize traffic, ensuring that high-demand applications like video streaming and VoIP receive the necessary bandwidth they require for optimal performance.

The router is also designed with operational ease in mind, offering centralized management capabilities through Cisco's suite of management tools. This allows operators to monitor performance, manage configurations, and troubleshoot issues more efficiently, reducing downtime and enhancing service reliability.

In summary, the Cisco uBR7246 is a powerful and flexible solution that meets the demands of modern broadband delivery. Its advanced technologies, modular design, high-level security features, and robust performance make it an ideal choice for cable operators aiming to provide high-quality services to their subscribers while staying ahead of the competition.
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