PreEqualization Analyzer: FAQ
Pre-equalization is a DOCSIS feature that enables cable modems to pre-distort their signal to compensate for impairments in the upstream network. With pre-equalization turned on, you can see an immediate 5 to 10 dB improvement in upstream SNR (MER).
It varies based on the CMTS. To turn on pre-equalization, add the appropriate command to the upstream configuration in the CMTS. If the command is already in there, then it’s turned on. Following are the commands for Cisco, Arris and Casa.
- Cisco CMTS Example: cable upstream 0 equalization-coefficient
- Arris CMTS Example: cable pre-eq-enable true
- Casa CMTS Example: logical-channel 0 pre-equalization
PNM is a concept developed by a group within CableLabs who realized that tools could be developed to analyze the pre-equalization data coming from the cable modems in order to locate where impairments are in the upstream network. Since pre-equalization is compensating for the impairments, a tool could show where the impairments are before they impact service for the subscribers. This can allow operators to proactively address the upstream issues in their cable plant as part of their routine maintenance, rather than reacting after service is affected when customers call to complain.
Yes, PreEqualization Analyzer is a hosted PNM application that analyzes the pre-equalization data, displays key metrics from cable modems such as tap values and upstream frequency response, and shows impairments such as group delay and micro-reflections. We display where the impacted modems are on a map, including the severity of the impairment and estimated distances involved.
Yes it does, which is a great reason to use PreEqualization Analyzer. Not only can you get the immediate benefits of a better customer experience that pre-equalization offers, but you will have a tool that will let you find and fix the impairments in your upstream network before they impact service for your subscribers.
No. PreEqualization Analyzer is a SaaS solution. Our server gets the pre-equalization data from your cable modems and our software analyzes that data. There is no server in your network and no probes required. In a sense, every cable modem in your network becomes a troubleshooting probe.
DOCSIS 2.0 or 3.0 is required for full compatibility. DOCSIS 1.1 devices have less resolution, with only 8 taps available instead of 24. DOCSIS 1.0 systems are not compatible. Even if you have a modem that is DOCSIS 1.1 or better, make sure that you are using a DOCSIS 1.1 or better config file with the modems. All DOCSIS compatible CMTS should work, although Arris BSRs need to be running software version 7.0 or higher.
This is controlled by the operator and can range from once every 24 hours to as often as once per hour.
PreEqualization Analyzer only shows upstream impairments, although there is a possibility that fixing an impairment on the upstream could resolve a specific issue that also happens to be affecting the downstream.
Yes. Although we do not have a mobile app for PreEqualization Analyzer at this time, it is a web-based application that can run in a browser on a mobile device. We plan on adding a mobile interface in the future.
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