Forum Discussion

Dave9's avatar
Dave9
Contributor III
5 years ago

Dynamic Range Window violation/Commanded Power - cause for concern?

Approximately 10 times per day, I get the following warnings in my cable modem (SB8200) event log:

05/09/2020 07:59 2436694061 5 "Dynamic Range Window violation"
05/09/2020 07:59 82001100 5 "RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=(redacted);CMTS-MAC=(redacted);CM-QOS=1.1;CM-VER=3.1;"

As far as I can tell, this corresponds with a change in the upstream power values, which currently vary between 47.0 dBmV and 49.0 dBmV depending on time of day.

I replaced the modem and had a tech come out due to very high upstream power values (53+ dBmV) and disconnections. Before the tech came out, downstream power values were +3 to +6 dBmV and upstream was +52 to +54 dBmV. The tech removed  some old equipment and possibly made some other changes which reduced the downstream power levels to -7 dBmV to -3 dBmV depending on frequency and time of day. Upstream power was reduced to +47.0 dBmV to +49.0 dBmV depending on time of day. Downstream SNR before and after is in the range of 42 to 43 dBmV.

I'm currently getting about 3,000 to 5,000 correctables and 0 uncorrectables per day on the higher frequency channels (750 MHz+) and a very small number (<5 per day) of correctables and 0 uncorrectables on the lower frequencies (350-450 MHz). Millions of correctables and 8 uncorrectables on the DOCSIS 3.1 OFDMA channel. I know the large number of correctables is normal but I've also heard that having any uncorrectables on the OFDMA channel is very bad.

My question is: are the dynamic range window violations (specifically having commanded upstream power above the top of the DRW) an indication of lingering problems that could get worse later? It's normally hard for me to schedule a time to have a tech come out but I'm on WFH for a bit longer so if there's still a lingering issue this would be a good time to get it fixed before it turns into a major problem. My biggest concern is that the outside wiring is almost 20 years old. Inside wiring is new and checked for tightness.

For reference, here is the full status page from my modem after running for 2 1/2 days. I'm not currently experiencing any obvious problems but I'm not sure I would immediately notice any momentary upstream glitches related to bad power adjustments. I guess one question I'd have for the technical people is: does the warning above mean that the commanded power level was rejected (possibly due to a spike in excess of 51 dBmV), or does it just mean that it doesn't like the current power level of 49 dBmV but it's setting that power anyway? The former would of course be a bigger concern than the latter.

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 831000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File OK
Security Enabled BPI+
DOCSIS Network Access Enabled Allowed

Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
9 Locked QAM256 831000000 Hz -4.2 dBmV 42.7 dB 9823 0
1 Locked QAM256 783000000 Hz -3.1 dBmV 43.5 dB 3021 0
2 Locked QAM256 789000000 Hz -3.0 dBmV 43.6 dB 2928 0
3 Locked QAM256 795000000 Hz -3.5 dBmV 43.3 dB 5165 0
4 Locked QAM256 801000000 Hz -3.4 dBmV 43.2 dB 4534 0
5 Locked QAM256 807000000 Hz -3.6 dBmV 43.2 dB 5737 0
6 Locked QAM256 813000000 Hz -3.8 dBmV 43.0 dB 7149 0
7 Locked QAM256 819000000 Hz -3.8 dBmV 43.0 dB 6177 0
8 Locked QAM256 825000000 Hz -4.2 dBmV 42.7 dB 9475 0
10 Locked QAM256 837000000 Hz -4.5 dBmV 42.5 dB 12287 0
11 Locked QAM256 843000000 Hz -4.8 dBmV 42.4 dB 14672 0
12 Locked QAM256 849000000 Hz -4.9 dBmV 42.5 dB 13817 0
13 Locked QAM256 855000000 Hz -5.1 dBmV 42.1 dB 15160 0
14 Locked QAM256 861000000 Hz -5.3 dBmV 42.2 dB 13101 0
15 Locked QAM256 867000000 Hz -5.4 dBmV 42.0 dB 13384 0
16 Locked QAM256 873000000 Hz -5.7 dBmV 42.0 dB 14972 0
33 Locked QAM256 357000000 Hz -6.1 dBmV 43.0 dB 1 0
34 Locked QAM256 363000000 Hz -5.9 dBmV 43.2 dB 0 0
35 Locked QAM256 369000000 Hz -5.8 dBmV 41.4 dB 1 0
36 Locked QAM256 375000000 Hz -5.7 dBmV 43.4 dB 0 0
37 Locked QAM256 381000000 Hz -5.4 dBmV 43.5 dB 1 0
38 Locked QAM256 387000000 Hz -5.3 dBmV 43.5 dB 0 0
39 Locked QAM256 393000000 Hz -5.4 dBmV 43.4 dB 0 0
40 Locked QAM256 399000000 Hz -5.3 dBmV 43.5 dB 17 0
41 Locked QAM256 405000000 Hz -5.1 dBmV 43.5 dB 12 0
42 Locked QAM256 411000000 Hz -5.1 dBmV 43.4 dB 10 0
43 Locked QAM256 417000000 Hz -5.2 dBmV 43.5 dB 0 0
44 Locked QAM256 423000000 Hz -5.1 dBmV 43.4 dB 0 0
45 Locked QAM256 429000000 Hz -5.1 dBmV 43.4 dB 0 0
46 Locked QAM256 435000000 Hz -5.1 dBmV 43.4 dB 0 0
47 Locked QAM256 441000000 Hz -5.0 dBmV 43.5 dB 0 0
48 Locked QAM256 447000000 Hz -4.9 dBmV 43.6 dB 9 0
159 Locked Other 300000000 Hz -6.3 dBmV 41.2 dB 1048014803 8



Upstream Bonded Channels
Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 2 Locked SC-QAM Upstream 23500000 Hz 6400000 Hz 48.0 dBmV
2 1 Locked SC-QAM Upstream 16900000 Hz 6400000 Hz 48.0 dBmV
3 3 Locked SC-QAM Upstream 29900000 Hz 6400000 Hz 49.0 dBmV
4 4 Locked SC-QAM Upstream 36300000 Hz 6400000 Hz 49.0 dBmV
  • Dave9's avatar
    Dave9
    5 years ago

    I had a service call today. The tech found that the line from the pole to my house was causing over 10 dB of downstream signal loss, and also found an issue at the pole related to upstream power. He replaced the cable and opened a maintenance ticket for the other issue, and said it should be fixed in a few days. My signals look a lot better and I'm very happy with the quick response from Cox.

  • Dave9's avatar
    Dave9
    Contributor III
    5 years ago

    I had a service call today. The tech found that the line from the pole to my house was causing over 10 dB of downstream signal loss, and also found an issue at the pole related to upstream power. He replaced the cable and opened a maintenance ticket for the other issue, and said it should be fixed in a few days. My signals look a lot better and I'm very happy with the quick response from Cox.

  • LatitiaS's avatar
    LatitiaS
    Moderator
    5 years ago
    Hello Dave9,

    If there is a signal issue outside the home, naturally this could cause problems down the line. Please send us an email with your address to cox.help@cox.com. We can then review the equipment diagnostics. Be sure to include this URL.

    Latitia
    Cox Forums Support Moderator
    • Dave9's avatar
      Dave9
      Contributor III
      5 years ago

      Thanks, I've sent a e-mail. Hopefully this will make sense to whoever reviews it. Today was a bit better but still have had 3 of these occurrences so far.

  • MichaelJ's avatar
    MichaelJ
    Moderator
    5 years ago
    Dave9, we look forward to receiving your email.

    Thank you,

    Mike
    Cox Support Forums Moderator
    • Dave9's avatar
      Dave9
      Contributor III
      5 years ago

      I sent the e-mail yesterday at 12:21 PM with a subject of "Question about modem errors". Please note that I don't use Cox for my e-mail. Does the e-mail need to be sent from a cox.net e-mail address in order to reach you?

      • BrianM's avatar
        BrianM
        Moderator
        5 years ago
        It does not, it looks like we have already responded yesterday.

        Brian
        Cox Support Forum Moderator
  • Dave9's avatar
    Dave9
    Contributor III
    5 years ago

    The e-mail technicians provided information stating that my signal levels look good (which I already know, and as we all know, signal levels are only a small part of overall connection quality - for example, noise intermittently getting into the line would not be reflected in signal levels).

    They were unable to answer my other questions about the meaning of the errors in the event log, which is understandable since these are highly technical questions. So I have been doing my own research and testing. It appears that these errors might be correlated with when one of the upstream channels is set to a power level of 49 dBmV (close to the upper limit of 51 dBmv). I will continue to research and report back any additional findings.

    As of now I suspect that the 20 year old line is allowing some level of noise into the system and when there is a burst of noise that would cause these errors, but I don't have enough technical knowledge to confirm that. An additional point in favor of noise is the low level of errors on the lower frequencies and higher level of errors on the high frequencies. As I understand it, when coax cable degrades, it begins to admit higher frequency interference before it starts to admit lower frequency interference.

  • Dave9's avatar
    Dave9
    Contributor III
    5 years ago

    I was in conferences today and confirmed that I got drops in my connection correlating with the times of the event below, so it is causing an issue. I've e-mailed the support e-mail address for assistance.

    05/12/2020 12:16 2436694061 5 "Dynamic Range Window violation"
    05/12/2020 12:16 82001100 5 "RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=(redacted);CMTS-MAC=(redacted);CM-QOS=1.1;CM-VER=3.1;"
    05/12/2020 12:09 2436694061 5 "Dynamic Range Window violation"
    05/12/2020 12:09 82001100 5 "RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=(redacted);CMTS-MAC=(redacted);CM-QOS=1.1;CM-VER=3.1;"
    05/12/2020 11:05 2436694061 5 "Dynamic Range Window violation"
    05/12/2020 11:05 82001100 5 "RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=(redacted);CMTS-MAC=(redacted);CM-QOS=1.1;CM-VER=3.1;"
    05/12/2020 10:41 2436694061 5 "Dynamic Range Window violation"
    05/12/2020 10:41 82001100 5 "RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=(redacted);CMTS-MAC=(redacted);CM-QOS=1.1;CM-VER=3.1;"
    05/12/2020 10:37 2436694061 5 "Dynamic Range Window violation"
    05/12/2020 10:37 82001100 5 "RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=(redacted);CMTS-MAC=(redacted);CM-QOS=1.1;CM-VER=3.1;"
    05/12/2020 09:37 2436694061 5 "Dynamic Range Window violation"
    05/12/2020 09:37 82001100 5 "RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=(redacted);CMTS-MAC=(redacted);CM-QOS=1.1;CM-VER=3.1;"