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Ignition · 01-07-2004, 09:53

The cable modem doesn't monitor upstream power, the uBR you connect to tells the cable modem to adjust its' transmit power constantly depending on requirements. The uBR has a target received power level that it wants the modems to get as close as possible to and when they deviate too far from this as part of standard DOCSIS protocol exchanges the uBR will demand that the cable modem adjust its' power.

But no that sort of change isn't normal, and you need to get an engineer to visit really - the T3 timeouts are probably due to overly large power adjustments, while a large power adjustment is taking place the cable modem cannot transmit, this is to avoid a rogue cable modem broadcasting at too high a power and drowning out signals from other modems on your upstream segment.

Suggest you call customer services, sounds more like an issue with your modem to be honest but can't be sure on that one. Either way engineer can check return path from your modem back to ntl and if need be swap the modem out.

Also if you have an attenuator fitted on your modem might be worth seeing how it goes with that removed. If the attenuator is supplying inconsistent attenuation or is attenuating the return as well as forward path a lot that could certainly cause issues..

01-07-2004, 09:53	#2
Ignition Permanently Banned Join Date: Jun 2003 Location: South-East London Age: 47 Services: Depends who's being serviced :p Posts: 2,588	Re: Gradually falling upstream power level The cable modem doesn't monitor upstream power, the uBR you connect to tells the cable modem to adjust its' transmit power constantly depending on requirements. The uBR has a target received power level that it wants the modems to get as close as possible to and when they deviate too far from this as part of standard DOCSIS protocol exchanges the uBR will demand that the cable modem adjust its' power. But no that sort of change isn't normal, and you need to get an engineer to visit really - the T3 timeouts are probably due to overly large power adjustments, while a large power adjustment is taking place the cable modem cannot transmit, this is to avoid a rogue cable modem broadcasting at too high a power and drowning out signals from other modems on your upstream segment. Suggest you call customer services, sounds more like an issue with your modem to be honest but can't be sure on that one. Either way engineer can check return path from your modem back to ntl and if need be swap the modem out. Also if you have an attenuator fitted on your modem might be worth seeing how it goes with that removed. If the attenuator is supplying inconsistent attenuation or is attenuating the return as well as forward path a lot that could certainly cause issues..