Community Forum

Internet Issues - High Upstream and Downstream Power Levels.

Highlighted
New Poster

Internet Issues - High Upstream and Downstream Power Levels.

I recently switched over to a CM1150V to avoid renting a modem.  After switching, T3 errors became so common that I had no internet access. I ran new cable from the box, checked/replaced all f connectors and splitters. When I have a two-way splitter from the tap running directly to my cable modem, my 4 upstream channels were 52-53 and downstream channels are is high 8's/low 9's. SNR is consistanly around 40.

 

I had a tech come out on Saturday who spent the entire time talking to his wife on speaker phone, and didn't really want to answer any of my questions. I asked him about the high downstream & upstream levels, but all he said was my signals were good, my modem was bad. The green box (cab or whatever you call it) is located about 15 feet away in my front yard, which he checked and said the signal was pretty strong. I asked him about a cable box issue too, he paused me tv, and said there, its fixed, and left a few minutes later.

Today, i removed the splitter and connected directly from the tap to the cable modem. My downstream levels are really high, upstream is just under the max, and my cable modem is showing absolutely no issues (No T3 errors at all). What can I do to get both my downstream and upstream lower, since using a splitter will bump my upstream out of range (to 53)?  Here's my current stats:

 

Procedure Status Comment
Acquire Downstream Channel 577750000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security Enabled BPI+
IP Provisioning Mode Honor MDD honorMdd(4)
 
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 13 577750000 Hz 13.9 dBmV 41.2 dB 0 0
2 Locked QAM256 10 559750000 Hz 13.6 dBmV 41.1 dB 0 0
3 Locked QAM256 11 565750000 Hz 13.3 dBmV 41 dB 0 0
4 Locked QAM256 12 571750000 Hz 13.3 dBmV 40.9 dB 0 0
5 Locked QAM256 14 583750000 Hz 13.7 dBmV 41 dB 0 0
6 Locked QAM256 15 589750000 Hz 13.4 dBmV 40.8 dB 0 0
7 Locked QAM256 16 595750000 Hz 13.2 dBmV 40.7 dB 0 0
8 Locked QAM256 17 601750000 Hz 13.2 dBmV 40.6 dB 0 0
9 Locked QAM256 18 607750000 Hz 13.3 dBmV 40.6 dB 0 0
10 Locked QAM256 19 613750000 Hz 13.1 dBmV 40.5 dB 0 0
11 Locked QAM256 20 619750000 Hz 13.2 dBmV 40.4 dB 0 0
12 Locked QAM256 21 625750000 Hz 13.1 dBmV 40.3 dB 0 0
13 Locked QAM256 22 631750000 Hz 13.2 dBmV 40.3 dB 0 0
14 Locked QAM256 23 637750000 Hz 12.8 dBmV 40 dB 0 0
15 Locked QAM256 24 643750000 Hz 12.9 dBmV 40 dB 0 0
16 Locked QAM256 25 649750000 Hz 13.3 dBmV 40 dB 0 0
17 Locked QAM256 26 655750000 Hz 13.6 dBmV 40 dB 0 0
18 Locked QAM256 27 661750000 Hz 13.4 dBmV 40.1 dB 0 0
19 Locked QAM256 28 667750000 Hz 13.2 dBmV 40.1 dB 0 0
20 Locked QAM256 30 673750000 Hz 13.3 dBmV 39.7 dB 0 0
21 Locked QAM256 31 679750000 Hz 13.6 dBmV 40.2 dB 0 0
22 Locked QAM256 32 685750000 Hz 13.8 dBmV 40.3 dB 0 0
23 Locked QAM256 33 691750000 Hz 13.4 dBmV 40.2 dB 0 0
24 Locked QAM256 34 697750000 Hz 13.5 dBmV 40.3 dB 0 0
25 Locked QAM256 35 703750000 Hz 13.7 dBmV 40.3 dB 0 0
26 Locked QAM256 36 709750000 Hz 14 dBmV 40.3 dB 0 0
27 Locked QAM256 37 715750000 Hz 13.8 dBmV 40.2 dB 0 0
28 Locked QAM256 38 721750000 Hz 13.9 dBmV 40.2 dB 0 0
29 Locked QAM256 39 727750000 Hz 14 dBmV 40.2 dB 0 0
30 Locked QAM256 40 733750000 Hz 13.7 dBmV 40 dB 0 0
31 Locked QAM256 41 739750000 Hz 13.9 dBmV 40 dB 0 0
32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0
 
Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 5 5120 Ksym/sec 36500000 Hz 48 dBmV
2 Locked ATDMA 6 5120 Ksym/sec 30100000 Hz 48 dBmV
3 Locked ATDMA 7 5120 Ksym/sec 23700000 Hz 48 dBmV
4 Locked ATDMA 8 5120 Ksym/sec 17300000 Hz 47 dBmV
5 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
 
Downstream OFDM Channels
Channel Lock
Status
Modulation /
Profile ID
Channel
ID
Frequency Power SNR /
MER
Active Subcarrier
Number Range
Unerrored
Codewords
Correctable
Codewords
Uncorrectable
Codewords
1 Locked 0 ,1 ,2 ,3 29 780000000 Hz 14.9 dBmV 39.2 dB 1108 ~ 2987 8694582 4493848 0
2 Not Locked 0 0 0 Hz 0 dBmV 0.0 dB 0 ~ 4095 0 0 0
 
Upstream OFDMA Channels
Channel Lock Status Modulation / Profile ID Channel ID Frequency Power
1 Not Locked 0 0 0 Hz 0 dBmV
2 Not Locked 0 0 0 Hz 0 dBmV
Highlighted
Expert

Re: Internet Issues - High Upstream and Downstream Power Levels.

The upstream power at 48 dB is o/k as long as it doesn't fluctuate higher. The downstream is indeed high. You could knock it down by using a forward path only attenuator. It won't affect the upstream power;

 

https://www.amazon.com/line-Signal-Forward-Attenuator-FPA6-54/dp/B07882H96R

 

If you are not actually having any connectivity problems, just leave it alone. No need to focus on the numbers.



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
New Poster

Re: Internet Issues - High Upstream and Downstream Power Levels.

My internet issue arise when I add the two-way splitter in, which I need to for my cable boxes. Once I add the splitter back in, my upstream jumps to 53, my modem is flooded with T3 errros in the log, and I lose connectivity. Is there anything else I can do in my end or do I need to get another tech out here?
Highlighted
Expert

Re: Internet Issues - High Upstream and Downstream Power Levels.

O/k well that's not good. Perhaps the connection from the street is impaired. It may be best to get a tech out to investigate / correct this one !

 

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 !



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
New Poster

Re: Internet Issues - High Upstream and Downstream Power Levels.

Got off the phone with Comcast tonight. The first tech was great and could see my connection dropping in and out. I was able to correlate what she was seeing with T3 timeouts. After escalating my issue to “tier 2,” everything went downhill. This lady tried telling me that my downstream power levels should be at least 35, and my upstream issues were caused by my modem. After calling her out on her nonsense, she abruptly told me “your do sis connection is great,” scheduled another tech to my house tomorrow, and got off the phone. We’ll see if he actually shows up.
Highlighted
New Poster

Re: Internet Issues - High Upstream and Downstream Power Levels.

Comcast tech came out again on Tuesday and checked the lines. My upstream level at the tap was 49, but he said that it was within Comcast's specs. I tried to get him to lower my upstream/get me in contact with someone who could, but that was a losing battle. After he left, I bought a Channel Vision C-0300 Return Path Amplifier from Amazon, which arrived today. I set it up on the longest run in my house, and my upstream levels have dropped to the low 40s/upper 30s. My CM1150V's log is empty, and my internet is back to what I'm paying for.

 

I'd suggest that anyone who is currently renting a Comcast modem and is planning on switching to a CM1150V check their upstream/downstream power levels in their logs before switching. The Comcast log was showing 49, but my CM1150V's upstream was b/t 50-53 on the same coax line. Once I brought it down to <46, my modem has been working flawlessly. 

Highlighted
Expert

Re: Internet Issues - High Upstream and Downstream Power Levels.

Glad you got it figured out ! Thread now being closed.



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!