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.
|Acquire Downstream Channel||831000000 Hz||Locked|
|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|
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.