As I work for a cable company and am a Network Engineer, I can attest that sub-optimal modem levels impact speed. However, this is dependant on the modem. (Some seem to handle a less clean plant.) Essentially you are looking for approximately 40 to 50 dB on the Reverse and between 5 to -5 dB on the Forward. The further you are from those ranges, the more likely you are to accumulate errors, dropped packets, retransmits and other networking headaches which chew up your bandwidth. Amazingly, that's why those little numbers on splitters and pads are important. They actually add up to something. Except for a directional coupler, every split in a splitter accounts for approximately 3.5 dB. 2 way = (2)3.5dB 3 way = (1)3.5dB, (2)7dB 4 way = (4)7dB As you can see to make a 3 way, you need to split one that is already split. These help pad and adjust the levels in addition to thelevels coming into the house. (Incoming levels could vary depending on equipment at the street.) Now, if you have a dirty plant where signal to noise is down at 20dB, a 35dB reverse could be impacted by the noise even though DOCSIS modems supposedly can handle a reverse down at 8dB to 58dB. That's the difference between a test bench controlled environment and the real world with snow and cold weather, cars hitting polls and peds, humidity, and a billion other variables. I think you'll now see, cable is NOT either ON or OFF. ============================ Daniel Rysztak, CCNA -----Original Message----- From: tclug-list-bounces at mn-linux.org [mailto:tclug-list-bounces at mn-linux.org]On Behalf Of Jack Ungerleider Sent: Saturday, February 07, 2004 10:49 PM To: TCLUG Mailing List Subject: Re: [TCLUG] New Comcast speeds On Saturday 07 February 2004 02:56 pm, David Phillips wrote: > Jima writes: > > My immediate guess is that maybe the coax feed to your cable modem is > > sub-optimal. I'm not a cable expert, though. > > Cable is either on or off. A bad signal (often caused by too many > splitters) will cause failure, not lower speeds. The way I understood it from the guy who did the cable check for my cable modem in Duluth was that there are optimal signal voltage levels for the data channels. If the signal is outside that level the modem can have trouble. To me that implies the possibility of sub-optimal performance. But like Jima I'm no cable expert. -- Jack Ungerleider jack at jacku.com _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota http://www.mn-linux.org tclug-list at mn-linux.org https://mailman.real-time.com/mailman/listinfo/tclug-list _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota http://www.mn-linux.org tclug-list at mn-linux.org https://mailman.real-time.com/mailman/listinfo/tclug-list