Community Forum

Strange power levels: cause?

Highlighted
Contributor

Strange power levels: cause?

If my understanding is right, the power levels and other numbers here are way out of whack.  What could be the cause of this?

 

(I have cabling installed by Comcast entering the house, entering a MoCA PoE filter, entering a Comcast supplied and installed two-way splitter, attached to house cable, attached to two-way Comcast supplied and installed two-way splitter, attached to Comcast cabling attached to a Comcast gateway.  Total db loss due to splitters is 3.5 X 2 = 7.  MoCA is active.)

 

Downstream
Channel Bonding Value
Index
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Lock Status
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Frequency
513 MHz
459 MHz
465 MHz
471 MHz
477 MHz
483 MHz
489 MHz
495 MHz
507 MHz
519 MHz
525 MHz
531 MHz
543 MHz
549 MHz
555 MHz
561 MHz
567 MHz
573 MHz
579 MHz
585 MHz
591 MHz
597 MHz
603 MHz
609 MHz
SNR
32.237 dB
30.885 dB
29.759 dB
28.062 dB
27.607 dB
30.002 dB
31.915 dB
33.377 dB
32.963 dB
31.994 dB
32.237 dB
33.487 dB
35.084 dB
35.595 dB
34.926 dB
33.957 dB
34.346 dB
33.957 dB
34.484 dB
35.084 dB
35.595 dB
35.595 dB
35.084 dB
34.926 dB
Power Level
-18.700 dBmV
-20.800 dBmV
-22.100 dBmV
-24.100 dBmV
-24.600 dBmV
-21.600 dBmV
-19.100 dBmV
-17.400 dBmV
-17.300 dBmV
-19.100 dBmV
-18.500 dBmV
-16.700 dBmV
-13.500 dBmV
-13.200 dBmV
-14.400 dBmV
-15.300 dBmV
-15.100 dBmV
-15.500 dBmV
-14.300 dBmV
-12.700 dBmV
-11.700 dBmV
-12.000 dBmV
-12.600 dBmV
-13.100 dBmV
Modulation
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
--
https://about.me/lairdnelson
Highlighted
Contributor

Re: Strange power levels: cause?

I'm using https://pickmymodem.com/signal-levels-docsis-3-03-1-cable-modem/ to discern what is "out of whack" and what is not.

--
https://about.me/lairdnelson
Highlighted
Expert

Re: Strange power levels: cause?

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.




I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Contributor

Re: Strange power levels: cause?

Thanks for your reply.  The splitters I documented are the only ones, and they were supplied by Comcast.  Sadly, I can't drop down to one splitter.

 

Do you have any wisdom to impart on the power levels in particular?  To my naïve eyes it looks like they're too hot, not too low.

--
https://about.me/lairdnelson
Highlighted
Expert

Re: Strange power levels: cause?

The downstream power is way too low ! So are the SNR's. You didn't post the upstream power levels.



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Contributor

Re: Strange power levels: cause?

Ah!  OK, I'm glad I asked, and thanks again for your reply.

 

Here's the rest of what I didn't post originally (sorry about that):

 

Upstream
Channel Bonding Value
Index
1
Lock Status
Not Locked
Frequency
9 MHz
Symbol Rate
5120 KSym/sec
Power Level
57.000 dBmV
Modulation
64 QAM
Channel Type
ATDMA
CM Error Codewords
Unerrored Codewords
2809626032
2805395047
2804831994
2540852341
1932508948
2805129755
2805389668
2805346925
2805390008
2805389951
2805384624
2805365019
2805336849
2805364486
2805361727
2805353133
2805342599
2805340987
2805334956
2805461320
2805455658
2805447904
2805443313
2805430375
Correctable Codewords
4358
25997
588032
180682182
788336829
272541
5944
40451
3288
3662
3132
1462
177
88
114
156
108
156
61
33
43
41
41
44
Uncorrectable Codewords
1079
1185
1237
1390944
2154537
1071
953
1165
946
1043
1017
1040
31
28
28
27
32
25
24
28
0
0
1
0
--
https://about.me/lairdnelson
Highlighted
Contributor

Re: Strange power levels: cause?

Let me ask you this, if I may: is low power due to the splitters (I've certainly been in places where there have been lots more splitters involved!), or more likely due to cable run?  (From the outside of the house, the cable cuts across a garage bay and into a combination furnace/telecom room.  Not very long, but what do I know?)

 

There are no unterminated jacks or anything like that, so no place (under my control) for noise to "leak" in to the circuit.

 

(I hesitate to get a tech out because usually they're under time pressure so they just swap out the cables the previous tech has installed and leave.  I understand that bang for the buck wise this probably is a quick way to get many problems fixed, but in this case I strongly believe something else is up.)

--
https://about.me/lairdnelson
Highlighted
Expert

Re: Strange power levels: cause?

It could be. The more splitters that are cascaded, the more the loss. It especially a problem if the incoming signal from the street / pole is already too weak.

 

And the upstream power it WAY out of spec too ! So much so that you've lost the bonding of the multiple channels....

 

 



I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!
Highlighted
Expert

Re: Strange power levels: cause?

You need a tech out to investigate as was stated earlier. Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home. Good luck with it !




I am not a Comcast Employee.
I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!