Intermittent Cable signal2003-02-01 (updated: 2014-08-17) by Allen D. Herring
I hope this story helps someone with the same problems I had. I started having problems one day with my cable TV. The picture was fuzzy sometimes. When this happened of course my cable modem would lose sync with the Cable Modem Termination System (CMTS) or be really slow. I called Cox @Home service and told them I was having problems come and check it out.
The guy they sent was somewhat knowledgeable and changed out the cable from the house to the telephone pole. He also told that my grounding block was "out of spec". This little block grounds the cable system to earth ground. After changing all that out my tests on bandwidth were incredible. I went from 100-200kb/s to over 1mb/s. I thought this is awesome!!! Simply changing out my cable and the grounding block shot my bandwidth way up. This isn't the end of the story unfortunately.
About three days later my cable modem went out altogether for no apparent reason! I kept looking at the TV and it looked great? What could be wrong? Called Cox again and this time they started giving me the run around. Oh, it must be your cable modem. We'll send someone out in a week. What the hell? I had to raise a lot of hell but they finally gave me a free month because of the trouble but, it was still going to be a week before someone would come out. I was pretty aggravated about this and decided to take matters into my own hands.
I'm a new MCSE by trade and I figured this would be a good challenge and learning experience. The telephone pole that provides cable, power, and telephone service to my house was the last one in a long line. I guess I'll work upstream. I went to the houses in this long line back the main road to our neighborhood. Only two people out of about 20 houses had cable modems and they were having similar problems. Ok, so it's not just me. I called Cox regular cable TV and lied and said my cable was out. They said no problem we'll have someone out the next day.
The guy came the next day and I said, "oh my cable TV just came back an hour ago but, now my cable modem is out". He left and worked on it for about a couple of hours then came back and told me that my cable TV and modem was going to be out for about 10 minutes. It was and when it came back everything was twice as good as it was before. I didn't think I could get more than 1mb/s but I have achieved during non peak times 1.8mb/s. The problem all along was a intermittent amplifier on the main trunk line that was feeding our neighborhood. The guy told me that the cable system has an amplifier about every 1/2 mile of so. Then why did I have cable TV and no cable modem. He said that the cable signal for TV was very forgiving and it didn't take very much to get it down the trunk line. The cable modem signal on the other hand is a very precise signal and must be very stable and clean.
I hope this helps someone.