How Can I Lower an Upstream Power Level?

Upstream power levels that are too high will affect a modem connection’s consistency. As the levels increase, the modem’s ability to connect to the provider decreases. As with all modulation signals, the upstream power level tends to fluctuate depending on various influences such as temperature. If the problem is on your end, it is usually the result of a bad splitter or poor cabling. Troubleshoot your upstream power levels by first capturing the initial results and then begin going through the procedures necessary to identify the problem.

Instructions

Preliminary Signal Capture

1. Open up a Web browser and input “http://192.168.100.1” in the address bar. This accesses the modem’s software interface.

2. Click the “Status,” “Signal” or “Statistics” link on the following page. While the names of the elements are generally similar, the exact name of the links and buttons on a modem’s interface will vary.

3. Locate the “Upstream” section and find the listed power level. Acceptable levels are between 30 dB and 55 dB. If the upstream power is above 55 dB, it needs to be lowered. Perform a full power cycle to see if levels improve.

Power Cycling Procedure

1. Disconnect the coax cable from your modem. Leave the power cord plugged in and let the modem sit idle for three minutes. If you have a router, go ahead and unplug it as well.

2. Disconnect the power cord from the modem and let the modem sit unpowered for two additional minutes.

3. Reconnect the coax cable to the modem. Once it is hand-tight, reconnect the power cord. Wait until the modem is back online by looking at the “Status” or “Online” light. If you have a router, reconnect its power cord.

4. Check your upstream power level again by accessing the modem’s software interface. In some cases, the full power cycle will resolve the problem. If still too high, continue reading to check line quality.

Probing Line Quality

1. Locate the first coax jack that enters your home. Figure out how you can connect your modem and computer together from this location. You need to check the signal level from the first entry point to confirm if the signal problem is actually in your home. If you have a wireless router or laptop, you can simply move the router or laptop to the modem. However, if you only have a desktop PC, you may have to do a bit more moving things around to test.

2. Disconnect your cable modem from the coax and power outlet then move it to the first coax jack. Reconnect the coax followed by the power. Test your signal levels again. If the upstream power is still too high at the first jack, there is nothing you can do on your end to resolve the problem. Contact your cable provider and advise them of the levels and steps you have taken to resolve. Continue reading if the levels have lowered, this indicates the problem is definitely somewhere between the first outlet and the outlet you regularly use for your modem.

3. Decrease the total number of splitters between your modem and the service box and check the line for sharp bends or deterioration. If possible, connect a single splitter at the first entry point and run a dedicated line from that splitter to your modem. Use as few splitters as possible for optimal signal quality. You should also test each of your splitters to determine if any of them are bad.

4. Disconnect each splitter from your line and bring them over to the first outlet in your home. Disconnect the cable modem from the wall outlet and add each of the splitters one at a time between the wall outlet and modem. Go to the modem’s software interface and look at the signal levels each time. This will allow you to see if any of your splitters are giving you problems. Dispose and replace any bad splitters.

References

• DSL Reports: What Kind of Signal Levels do I Want on My Cable Modem?
• Cable Labs: DOCSIS Specifications