Contributor
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40 Messages
increase upstream power
Arris says my upstream power is to low. It should be 45 to 50 and mine is 44 so they will not troubleshoot until it is corrected. They said my provider can correct this.
Contributor
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40 Messages
Arris says my upstream power is to low. It should be 45 to 50 and mine is 44 so they will not troubleshoot until it is corrected. They said my provider can correct this.
BruceW
Gold Problem Solver
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26.4K Messages
2 months ago
Arris began saying that upstream QAM signals should be "at least 45 dBmV" several years ago. I don't know why, because it's complete nonsense.
The upstream signal levels are controlled automatically and continuously by Comcast's equipment and do not need to be above 45 dBmV. That's because, as long as upstream levels are not maxed out, what's important is not the level at the modem, it's the level (and quality) of the modem's signal as received at Comcast, which they control by adjusting the modem's transmit level. In fact, many customers have service that works perfectly fine with upstream modem signal levels below 45 dBmV. Some even operate with the upstream below 35 dBmV.
Comcast's signal level ranges are given in https://forums.xfinity.com/conversations/your-home-network/connection-troubleshooting-tips/602da777c5375f08cdea3db9. If Arris' products did not work in those ranges, CableLabs and Comcast would never approve the devices.
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user_a9365
Contributor
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40 Messages
2 months ago
I appreciate your reply but that puts me in a bad spot because they will not help me until the level is increased.
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BruceW
Gold Problem Solver
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26.4K Messages
2 months ago
If you insert a 3db attenuator (even a two-way splitter will do) in line with the modem it will increase the upstream power level reading. It will also lower the downstream level by 3db, which may be OK depending on where the downstream levels are now.
What "troubleshooting" do you expect Arris to do? Manufacturers can't really access the systems that communicate with the modem, nor diagnose signal level problems.
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user_a9365
Contributor
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40 Messages
2 months ago
Where would I get a 3db attenuator? What type of splitter could I get? I was told not to use splitters. All my downstream levels are around 3 and 4 dBmV.
I have an SBG8300 and I believe it MAY be going bad. My speeds are kind of all over and I wanted them to replace it if it is going bad since it's still under warranty.
Arris told me my provider could fix this from the office. I don't know anything about it, I just use it.
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user_a9365
Contributor
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40 Messages
2 months ago
So you believe a 3db attenuator would bump my upstream from 44 to maybe 50? I found a 3 and a 6db.
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BruceW
Gold Problem Solver
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26.4K Messages
2 months ago
A 3db attenuator should increase a 44 dBmV upstream to 47 (the attenuation adds to upstream power and subtracts from downstream power). I'd avoid 6 db as that would put you at 50 dBmV which is Comcast's max for upstream power.
Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.
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user_a9365
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40 Messages
2 months ago
Thank you I will try it. I don't understand any of this stuff. Hopefully Arris will talk to me if it works.
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BruceW
Gold Problem Solver
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26.4K Messages
2 months ago
I should have said before: Arris' statement that your provider could "fix this from the office" is not correct. It just doesn't work that way. Comcast's systems automatically control modem upstream power to keep the level they receive at 0 dBmV (AKA 1 millivolt). Beyond that, power level adjustments require "boots in the field".
Please do, if you have the chance, let me know how this turns out please. Appreciate it!
Please be aware that there are 2 kinds of responses in this Forum: Replies and Comments. When you Comment on a post by scrolling down to "Comment on this post here...", I am notified of your response. But if you select Reply, I am NOT notified and may not be aware of your response.
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user_a9365
Contributor
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40 Messages
2 months ago
I bought a 3db attenuator and you were correct. My upstream levels are about 48 now and my downstream are about -1 to +1. Arris has no excuse not to talk to me now. I really appreciate your help.
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