I am not sure where to put this, but this seems as good a spot as any.

Can bare coax cable have db spikes? Had the cable guy out due to cable modem dropping a couple times a day. He said its due to line noise. Says he see 10db spikes in the cable. He tested the cable when it had no connections at all.

All my cable modem setting seem to be correct up stream and down stream power levels are within range. It seems like every cable in the house he tested except for one was quite noisy. The thing is this problem only start a month ago. Some cable in the walls in at least 8 months old now and the other has been in the house for a good 5 years. Suddenly there is this problem. Could it really be the lines and noise spikes doing this? And if so how can I reduce the line noise. Replacing the cable is pretty much out of the question for now.

Oh the cable and HD signals are just fine. No issues

Thank for any advice.

Yes, it's called impulse noise and it is one of the biggest headaches for cable systems.

IMO... have another "cable guy" identify and resolve the issue. Escalate to a supervisor. That's what you pay for on a monthly basis.

It should be simple...
drop from pole/ped to your home.
splitter... one to TV one to modem.
TV good, modem bad.

Start with the obvious. Bad splitter, bad cable (or connector) from splitter or perhaps a bad modem.

ya, I will have to get them out here again. He tested every line in house that I have in use. They all had noise even when connected to nothing. he replaced a few ends that looked bad and put a new splitter in place. I asked him what the noise was from the box and he said he could not measure that. I though that was a little strange. He said there would be noise for everyone around if it was at the box. That did not seem right either.

Thanks,

He should easily be able to measure noise out of the back of the box. Just attach a jumper from the meter and read ingress parameters as per usual. You won't get noise too often out of boxes but it can happen. More commonly you'll get noise directly out of TVs but if they have boxes that shouldn't be an issue.

Some lines, like older RG-59 start generating a good bit of noise just for the fact that they've been there so long and have been susceptible to the usual wear and tear. Or possibly they were sub-standard to begin with. Depending on the layout of your house it's not always practical/possible to replace lines in the exact same location though.

Anyway it's fairly easy to track down with a meter - if there's no noise out of the box but noise at the other end of the line then the line's no good.