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Toronto, ON
·TekSavvy DSL

[Cable] 8-10dbmv upstream power drop

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Two days ago
I just noticed that two days ago my modem lost sync, and when it came back it appears the upstream power dropped by 8-10dbmv depends on the channel... I was in the happy range of 40-42dbmv for a long long time...

I know lower is better for upstream power, but are these numbers too low?

There have been some weird shenanigans since i was switched from McNicoll to Comstock POI a week ago. Even cable TV seems to have been affected with some weird channel unavailability. I wonder they serve CableTV from the same POI as the internet.


Toronto, ON
»Adelphia High Speed Internet »FAQ: Acceptable cable modem signal levels.

That FAQ says it should be between 8 and 55, with the recommended level between 35-52. However I've read that a Tx power level below 30 may cause connectivity issues.

I'm not sure how their TV and internet network works, but last month my cable modem lost sync a couple days for hours at a time, and each time I was also unable to tune to a few cable TV channels. As of now I still seem to be on McNicoll, not sure if that will change though.

Sudbury, ON
reply to HiVolt
@Hivolt, I wouldn't be so worried....what'll happen is when the modem is reaching out to the CMTS during upstream and downstream ranging, it will connect at that same level always whenever a power cycle occurs....its possible that they made some changes to the physical plant to clean up some of that spectrum....in reality it just means that your modem doesn't have to shout as loud to be heard .

If there's an issue your modem will ratchet up the upstream power level as needed, but there's really no such thing as too low....the cable tv wouldn't be directly related unless they're putting tv channels in that 5-42mhz range which I would say 99.99% that they're not since those are all served on the downstream side and not the upstream side...

Long story short, if you run tests and everything is still good, don't worry, everyone will have slightly different signal levels depending on where they are on the physical plant...if they've made a small design change, and they've done it right, there can be variances based on tap plate, perhaps your tap plate was changed again based on another issue, one you might not have even seen or know about unless you knew the values of the tap plates that were out there previously....

So, again, I wouldn't worry, some people are at 33dbmv, some are at 50 and have the exact same experience...



1 edit
reply to HiVolt
Something similar happened to me, not too long ago. Only, instead of my upstream power levels going down, they went up from about 33-34 to 36-39. Also, my downstream power levels were hovering around 0, then they went to the -8 to -9 range.

The same day it happened, a Robbers van was on the street hooking up a new customer at the pedestal. He must have split the signal, causing my new (slightly worse) stats. Fortunately, so far as I can tell, it hasn't really affected my connection stability.

So, it could be a Robbers/Link-On tech recently mucked around with the pedestal you're connected to, on your street. Maybe the opposite of what happened to me, happened to you. Someone on your street was disconnected?


Scarborough, ON
reply to HiVolt
I've been sitting at around 31-33dBmV for my upstream channels for a while now and I haven't experienced any issues.