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smtips's avatar
New Contributor II

Upstream Power SB 6190

My speeds have been getting pretty bad on the upstream side. It's gone from 4 to 20 Mbps up and should be 30 because that's what I pay for.  Had a tech here yesterday. All lines are good (they were all replaced appr. 3 years ago including the drop and  tap). Tech put an attenuator on my modem at my request and raised the upstream power to BARELY adequate for this modem, it was running 38-41 and Arriss recommends minimum 45. The upstream issue was okay for a while yesterday, and today it's right back down where it was.

Here are Arriss's own level requirements:

  • Upstream Transmit Power Level
    Channel US Channel Type Symbol Rate Acceptable US Power Level
    TDMA 1280 Ksym/sec +61 dBmV to 45 dBmV
    ATDMA 2560 Ksym/sec +58 dBmV to 45 dBmV
    5120 Ksym/sec +57 dBmV to 45 dBmV
    TDMA 1280 Ksym/sec +58 dBmV to 45 dBmV
    ATDMA 2560 Ksym/sec +55 dBmV to 45 dBmV
    5120 Ksym/sec +54 dBmV to 45 dBmV

    Three or more
    TDMA 1280 Ksym/sec +55 dBmV to 45 dBmV
     2560 Ksym/sec +52 dBmV to 45 dBmV 
     5120 Ksym/sec +51 dBmV to 45 dBmV
  • Refresh the page at least twice to identify variations in SNR, Downstream Power, and Upstream Power.   

    NOTE: If the either of the signal levels are outside of the acceptable range, power cycle or factory reset the modem. 

  • Contact the cable provider to adjust the signal level to the acceptable level range.


Here are the levels of the modem after installing an attenuator:

Upstream Bonded Channels

Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 2 5120 kSym/s 23.30 MHz 44.75 dBmV
2 Locked ATDMA 4 5120 kSym/s 36.30 MHz 46.25 dBmV
3 Locked ATDMA 3 5120 kSym/s 29.80 MHz 44.75 dBmV
4 Locked TDMA and ATDMA 1 2560 kSym/s 18.40 MHz 43.25 dBmV

It seems that everything that could be done by a tech on the premises was done yesterday. Although one is coming here tomorrow again, because that's just what happens when you call support.

Does this look like some adjustment needs to be made at the CMTS? Because I've had this modem for 1 year and 1 month and there was no issue and suddenly there is now. I do speed tests about once a week and this only started being an issue.

Arriss says "Contact the cable provider to adjust the signal level to the acceptable level range."

I'm really not going to go round and round with you guys like I did 3 years ago with many tech visits and no resolution til I contacted your Advocacy dept. Just the fact I HAD to go there before your people actually did a thorough job was appalling.  Done that been there. It took at least 30 calls and 10 tech visits and finally a call to the Advocacy people, to find out it wasn't an issue here at all (as I knew), it was noise on the line someplace supposedly.  I just won't do all this again, I will simply dump Cox, so I hope someone's gonna be looking at the CMTS this time a LOT sooner than they did before and track back where the noise is happening. I'm getting too old for this runaround I got before and simply won't do it this time.

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  • cpljp's avatar

    For one, there is no difference between having an upstream power in the 30s vs the 40s. There is a "sweet spot" of 44-48 dBmV, but that has nothing to do with upload speeds, its more to help the modem with adaptive equalization purposes for the modulated waveform on your upstream QAMs. The Arris supplied levels are on the high side actually before modem failure. So your attenuator is doing nothing and your previous upstream power levels were fine. In fact, all the attenuator is going is causing the modem to raise its transmits just to get lowered again 3 inches later after the attenuator. There is also nothing that would be able to get adjusted at the CMTS side to fix your upload levels. 

    If it is noise like you said it was last year, it won't be at the CMTs either. It will be somewhere in the cable plant or coming from someone's home. What you can do is ask the technician who comes tomorrow to call his/her maintenance tech and have them take a look at the node for noise. And if there is confirmed to be noise, then the tech can submit a ticket to plant maintenance to track the noise out.

    There is a chance this isn't the issue this time though. I'm assuming you've already bypassed the router and tested directly to the modem right? No QOS or anything on the router?

  • Hello,

    Everything cpljp stated was correct.  Being that we are going to need some more information from you so we can look into it and see if we have an area issue or something we may need a tech out for.   Can you please reach us on Twitter at @CoxHelp, visit us on Facebook, or email by at Provide us the name on the account with the full service address with a link to this thread so we can get started.


  • smtips's avatar
    New Contributor II

    I already stated a tech was coming here tomorrow. I don't use Twitter and I don't use Facebook.

    Please answer me why Arriss is stating the Acceptable US Power Level minimum as 45. This other guy said something like Arriss purposely said it's high, yet THEY MAKE THE MODEM. Does that make sense why the manufacturer would state a minimum that isn't true? It doesn't to me. Yet you are recommending this modem on your list of compatible modems.

    You also said you'd address why your forum search doesn't work AT ALL in this thread, yet you said nothing about it. What good is a search if it isn't working?

    Incidentally, I was gone for several hours today and returned a half hour ago (AZ 9 pm) and tested and the speeds are fine now. But I'm not canceling the tech visit until I know the speeds are consistent tomorrow at the same times they weren't today. It could be like before where the speeds went to pot overnight, but at a different time of day now. Maybe some jerk on the network is running 50 bittorrent connections or some nonsense. So we will see tomorrow.

    Lastly, tomorrow's tech visit will be the only one I do and something best progress from this visit, because I absolutely refuse to do THIS again:

  • Hello,

    You didn't have to use Facebook or Twitter.  We mentioned you could also email us to relay information.  Sorry your search from the other forum was not working and will need to look into that.  We are happy to see a tech is scheduled to come out to assist you with the connection issues you are seeing.  Another thing you can look into with the Arris 6190 modem is concerns with the Puma 6 chipset.  Depending on what they find tomorrow you might want to look into this as well. 

  • cpljp's avatar

     I can't answer why their customer service is trained to give those power levels out, but I can say it is not correct. They've been doing this for years, and your are right, it doesn't make sense.

    When your modem starts outputting an upstream of over 49-50 dBmV, it actually starts causing packet loss and latency issues and gets worse and worse every additional dB of attenuation introduced, so Arris's specs are way off. Really, your return levels represent the attenuation measured in decibels between your modem and the input of the CMTS as the signal makes its way through your wiring, splitters, hardline and passives in the plant, amplifiers in the plant, the node, fiber, and then again the coax and splits in the headend. Having transmits of 35dBmV versus 45 dBmV simply means you have 35 dBs of attenuation vs 45 dBs of attenuation. But, when you start hitting the 50s, your modem starts transmitting at the high end of the docsis specs and causes issues.

    Yes, someone running 50 bit torrent congestions could congest the return path and cause slow upstream speeds.

    If it is noise, unfortunately its just a nuisance byproduct of the technology. DSL/telco has to deal with noise as well as even fiber (dirty connectors/splices and improper bends cause reflections/refractions and noise). Wireless cellphone companies have to deal with noise as well on their LTE band, only difference is since its wireless if you see degraded speeds, no one really complains en mass. 

  • smtips's avatar
    New Contributor II

    So after the tech was here today, and I told him your suggestions, he got the same low speeds on his meter. He checked the tap just to verify, called ops and discovered there are already 2 tickets open for this very issue. So he's opening a 3rd ticket and marking it as critical because it's been several days now. At least we now know the issue.

    One interesting aspect of this is that the speeds were good last night and the issues returned again today during the day. When I had all these major issues a couple years ago or so, the speeds would be bad at night and okay during the day. So whatever.

    It IS very unfortunate that the right hand doesn't know what the left hand is doing at Cox. The rep on the phone when I had a tech here two days ago SHOULD have known about these tickets, and instead sent the tech to a known issue. And the next rep should have known, but sent a tech out for today. I will only say one more thing about that: You guys keep raising our prices and your costs go up because of stupidity like that. I will definitely be calling for credits on my bill for every day this isn't getting the speeds I'm paying for.

    I contacted Arriss after getting the DNS Benchmark tool from and finding that over 50% of the DNS benchmarks were deplorable (really only 3 were 100% as they should be, OpenDNS). Turns out that, unlike Newegg's site says, these SB 6190's have a TWO year warranty, not a one year warranty. I'm not sure if I should exercise that option and get a replacement or not because it has been working okay. OpenDNS servers were the only ones that gave me a 100% reliability reading so I may just go ahead and change to those after I hook my router up again. The reps at Arriss had me do a factory hard reset and gave me a case number to call them back with. That obviously did nothing for the speeds because of the Cox issue. So I guess maybe I won't hassle with a replacement for now. Maybe I will jump on the class action lawsuit that's out there about the Puma chipset if I can though.

  • EdwardH's avatar
    Valued Contributor
    @Smtips You can use any DNS servers you prefer with the connection it would not have a negative impact on the connection using OpenDNS, Google's DNs or any other DNS servers you prefer. As far as credits we can review the account for the total days effected once we have resolved the speed issues.

  • smtips's avatar
    New Contributor II

    I'm on the phone right now with an agent and after a lot of looking around initially she told me the tickets had been closed and marked as resolved. But I was persistent about the issues still being there, she was ready to open another ticket about it (because sending more techs here makes no sense at all), but checked with her supervisor first. They dug deeper and found out that indeed the maintenance ticket is still open about these issues.

    Had I NOT been persistent, this wouldn't have gotten more attention and another ticket would have been created. So now it's a week later, and the "critical" 3rd ticket the field tech sent up a week ago is STILL OPEN and STILL not resolved. What the heck, are your people at the head end on vacation??

  • Hello, apologize as sometimes finding related maintenance tickets become difficult to locate for some.  I checked the status on this ticket you have with them.  It is still classified as "major" so it does take a priority.  Over the holiday weekend the teams only address total outages due to staffing.  This may be the reason the ticket was not updated today as them may be catching up.  I have reached out and spoke to the local network monitor department and the will place a note on this ticket to be the pick back up to finish tracking the underlying noise issue under the data carrier. If you need to follow up on the ticket you are welcome to contact us via Facebook, Twitter or Email. 

  • cpljp's avatar


    do you live in Phoenix by any chance? East valley or central (tempe, phx, chandler)?