Consumers - Cable Modem RF Signal Specifications

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Cable Modem RF Signal Specifications

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What are the acceptable Cable Modem RF Signal levels?


Cable Modem RF Signal Specifications

All DOCSIS cable modems require that the RF signals fall within a very specific range to be an acceptable level for the modem to operate properly. These levels apply to all SURFboard cable modems and cable modem/gateways.

Downstream Signal to Noise Ratio (SNR):25dB or greater
Downstream Power Level:+15 to -15dBmV
Upstream Transmit Power Level:less than 58dBmV

These values are absolutes. If the cable modem or gateway is experiencing levels that approach the minimum or maximum acceptable levels then it is a warning sign that there is a possible cable plant issue. If the cable connection at the modem is OK, then the you need to refer the caller to their cable operator to address the issue.
Agents should be making an effort to help the caller to understand which value is incorrect so that they can provide the cable operator with that information.
Checking these values is the same for all SURFboard cable modems and gateways.

To verify these signal levels, launch a web browser and navigate to and navigate to the "signal" page. On cable modems this can be accessed directly by entering in the following URL:, on gateways you must first log in and then select Cable -> Signal to see the information.

Here are some screen shots of the SB4100 and the SBG1000:






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