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| comcast heat related failures http://interceptradio.com/bbs/viewtopic.php?f=1&t=1139 |
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| Author: | 2wayguru [ Mon Jul 24, 2006 7:06 am ] |
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This is very typical comcast! I have had problems with heat and when it would rain hard or rain for a long period of time. The problem lies in the amplifier box that is out on the pole, I had to fight with comcast for them to send out a line tech to fix the problem because the problem was in the box not at my house but they sent the home techs out to tell me that they could not find a problem with my equipment and that everything in the house was fine ( NO S(*&% sherlock) I was out of service for almost a month and that they tried to charge me for sending someone to my home to tell me there was nothing wrong. Finally I got a guy that was intellegent and was not a minimum wage moron, he threw a meter on the line coming from the pole to the juction box that is in the ground and said " Hey there is a signal problem from the Pole! Let me get a line Tech out!" Well to make a long story short they line tech came out, opened the amp box and about a quart of water came out, he replaced the the box and guess what? My Modem was screaming again. Have them check the amplifiier box on the pole I bet that will solve your problem........ |
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| Author: | Rich [ Mon Jul 24, 2006 8:22 am ] |
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Overheated amps/LE's are one possible cause. Heat expansion of coax increases attenuation so there are cases where you will experience loss due to improper amplifier spacing. I've also seen cases where cable companies disable AGC on their amps but of course the downside of this is that they can't compensate for the heat-related attenuation. One easy way to pick up a few dB for your modem is to split your modem off your cable feed with a DC-6 instead of a standard splitter. Of course 2-way house amps work too but they don't have the greatest noise-figures plus they can cause the modem transmit level to be too low which further degrades your upstream SNR. |
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| Author: | Larry [ Wed Aug 02, 2006 6:10 pm ] |
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Yes the heat is causing quit a stir. We/I mean Comcast has also upgraded/changed the upstream modulation from qpsk to 16quam. This is an ongoing process and will take a while to complete...IE if your upstream transmit was a little "hot" before...its screaming now. We...I mean Comcast have seen a max transmit from modems (upstream transmit...the power your modem puts out to get your upstream....UPSTREAM) FROM 59 TO A WHOPPING 64db. 55 is the max for a "reliable connection" on either modulation schemes. Depending on your modem type in 192.168.100.1 into your browser and check the signal portion of your modem diags. If your upstream trnasmit is above 55.....yeah your having issues. If your downstream receive is below -15, yes your having problems. Most customer premise issues exist on the premise. If you have a tereyon modem or a no name AMBIT modem please feel free to ask how to get to those pages.....password and a little extra typing required. BTW You didnt hear this from me and I will say our system is under a hell of a lot of stress with the digital simulcast going on. Email me for more info Larrymax at a place called gmail dot com (hiding from the bots :) |
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| Author: | Rich [ Fri Aug 11, 2006 12:24 pm ] |
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QPSK tops out at +58dbmv and 16QAM is a few dB less. Some modems (RCA, etc) will top out at +61. One problem with 16QAM is modems with high-transmit will fall off since the transmit power is less and the SNR requirement is greater. If you think 16QAM is a pain, just wait until you guys catch up with technology and play with 32QAM+ upstream. Thats what I had to deal with on my last DOCSIS 2.0 system upgrade. |
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