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Re: What are normal signal levels?

Tek
Problem Solver

Re: What are normal signal levels?

@EG 

 

Found this thread as I am waiting for maintenance to correct signal issues from the pole.

 

My XB7 has an Upstream Power Levels:

Index 1-4 

Power Level

51.5 dBmV
52.3 dBmV
52.0 dBmV
51.5 dBmV

 

My Downstream Power Levels:

Power Level

-2.5 dBmV
-2.5 dBmV
-2.6 dBmV
-2.8 dBmV
-2.9 dBmV

 

Would appear my Upstream values are too high? 


Tek
EG
Expert

Re: What are normal signal levels?

Yes. There is no wiggle room to allow for inevitable fluctuations. 40 to 45 dB would be the desired value.

 

The downstream power is o/k bit you didn't post the SNR values.



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Tek
Problem Solver

Re: What are normal signal levels?

@EG 

 

The Tech who checked my signals from the tap on the pole said the signal needs to be balanced and that the amp on the street is causing issues. Here are the signals. I certainly do not understand all this: 

 

 

Downstream:

 
Downstream
Channel Bonding Value                               
Index
29
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
30
31
32
159
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
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Locked
Frequency
625 MHz
457 MHz
463 MHz
469 MHz
475 MHz
481 MHz
487 MHz
493 MHz
499 MHz
505 MHz
511 MHz
517 MHz
523 MHz
529 MHz
535 MHz
541 MHz
547 MHz
553 MHz
559 MHz
565 MHz
571 MHz
577 MHz
583 MHz
589 MHz
595 MHz
601 MHz
607 MHz
613 MHz
619 MHz
631 MHz
637 MHz
643 MHz
701000000
SNR
41.1 dB
42.0 dB
41.8 dB
41.6 dB
41.6 dB
41.5 dB
41.4 dB
41.2 dB
41.0 dB
40.3 dB
40.4 dB
40.9 dB
41.2 dB
41.2 dB
41.3 dB
41.4 dB
41.5 dB
41.5 dB
41.4 dB
41.4 dB
41.3 dB
41.4 dB
41.7 dB
41.6 dB
41.5 dB
41.3 dB
41.4 dB
41.3 dB
41.3 dB
41.1 dB
41.2 dB
41.0 dB
NA
Power Level
-2.5 dBmV
-2.4 dBmV
-2.5 dBmV
-2.7 dBmV
-2.8 dBmV
-3.0 dBmV
-3.3 dBmV
-3.5 dBmV
-3.9 dBmV
-4.5 dBmV
-4.4 dBmV
-3.8 dBmV
-3.5 dBmV
-3.8 dBmV
-3.5 dBmV
-3.5 dBmV
-3.0 dBmV
-2.9 dBmV
-3.0 dBmV
-2.8 dBmV
-2.9 dBmV
-2.6 dBmV
-2.2 dBmV
-2.0 dBmV
-2.2 dBmV
-2.3 dBmV
-2.1 dBmV
-2.4 dBmV
-2.2 dBmV
-2.6 dBmV
-2.5 dBmV
-2.8 dBmV
NA
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
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
256 QAM
OFDM

 

 

Upstream:

 
Upstream
Channel Bonding Value  
Index
1
2
3
4
Lock Status
Locked
Locked
Locked
Locked
Frequency
36 MHz
30 MHz
23 MHz
17 MHz
Symbol Rate
5120
5120
5120
5120
Power Level
51.0 dBmV
51.8 dBmV
52.0 dBmV
51.5 dBmV
Modulation
QAM
QAM
QAM
QAM
Channel Type
ATDMA
ATDMA
ATDMA
ATDMA

Tek
EG
Expert

Re: What are normal signal levels?

It's just the upstream power that is too high. The downstream values are good.

 

You should get the techs re-involved, especially if you were told that the problem lies beyond your premises,

 

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 indeed lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home.
Good luck !



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Tek
Problem Solver

Re: What are normal signal levels?

The employees on this forum confirmed the tech on 1/30/21 did refer it to the maintenance team, but said I must wait 14 days for them to fix the problem. The 14th day is on Saturday. 

 

The on-site Tech did climb the pole and verify with his meter (and my house disconnected from the pole), that the upstream signal was too high. Nothing to do with my home as he experienced the same issue at the pole. 

 

We are having various issues because of it.  


Tek
EG
Expert

Re: What are normal signal levels?

You'll have to keep leaning on them. The wheels turn very slowly.



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Tek
Problem Solver

Re: What are normal signal levels?

Maintenance and a tech came out. They adjusted the pole and checked my internal wiring. Everything is now within spec. Speeds are exceeding what my plan offers up and down.

 

Here are the new levels:

https://imgur.com/a/EBTYR6s 


Tek
EG
Expert

Re: What are normal signal levels?

FWIW, the upstream power is still too high. There is no wiggle room to allow for the normal inevitable signal fluctuations. Especially when the warmer Summer weather arrives as the outside temperature will indeed cause it to rise. It's a problem waiting to happen.

 

Hope things hold up for you. Good luck !



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Tek
Problem Solver

Re: What are normal signal levels?


@EG wrote:

FWIW, the upstream power is still too high. There is no wiggle room to allow for the normal inevitable signal fluctuations. Especially when the warmer Summer weather arrives as the outside temperature will indeed cause it to rise. It's a problem waiting to happen.

 

Hope things hold up for you. Good luck !


Why would they tell me it is fine then? Literally, had a pole truck and another Xfinity tech claim I am good. They even said the modem is reporting 50/51.  

 

Quick search seems to show it is below maximum allowable levels (I assume the bold one is my signal): 

 

50 dBmV maximum for OFDMA (DOCSIS 3.1)
52 dBmV maximum for A-TDMA, TDMA & SC-QAM (DOCSIS 3.0)
53 dBmV maximum for S-CDMA DOCSIS 2.0 (All Modulations)
54 dBmV maximum for 32 QAM and 64 QAM. (A-TDMA DOCSIS 2.0)
55 dBmV maximum for 8 QAM and 16 QAM. (DOCSIS 1.0, 1.1)
58 dBmV maximum for QPSK. (DOCSIS 1.0, 1.1)

 

What should my Signal Levels be? Comcast High Speed Internet FAQ | DSLReports, ISP Information


Tek
EG
Expert

Re: What are normal signal levels?

That is if they remain rock-solid stable (which they won't). And what you posted are not the Comcast plant / system specs. They are the only ones that matter. I guess you didn't see the point that I was making about the inevitable fluctuations, and there is not any wiggle room to allow for it... 40 to 45dB is the desired safe range.



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Tek
Problem Solver

Re: What are normal signal levels?

Would an amp fix it? I don't have an amp. My connection comes into the side of the house, runs about 2 feet to the splitter. The Modem and DVR are on the main splitter from the drop. The first splitter has 1 in and 3 out. The 3rd port on the first splitter splits to the two satellite boxes (XiD). on the second splittrer. I really don't see how any reconfig of this will improve the upstream signal. 

 

What is the "spec" where it if it exceeds I will have issues? If anything, extreme cold made it worse and it is still the same temps since the techs repaired the pole connection. 

 

For the last two weeks, the service has been rock solid. My 600meg plan is bringing 720meg down and 18meg up. 

 

Splitter config: https://imgur.com/f6SFnTS

 

 

 

 


Tek
EG
Expert

Re: What are normal signal levels?

Is the modem on the -3.5dB port of the first splitter ?



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Tek
Problem Solver

Re: What are normal signal levels?

I believe it is, but can double check by disconnecting it.

 

It is possible it is the main DVR, but I am not sure. If it is the main DVR, will that have the DVR then have signal issues or they more tolerable? 


Tek
Tek
Problem Solver

Re: What are normal signal levels?

@EG So the 3.5db leg of the first splitter goes to the second splitter with the secondary XiD Boxes. The modem and DVR are on the -7db leg of the first splitter. 

 

Line Tech said the pole was sending 42. If the modem is on a 7db loss leg then 42 + 7 = 49db to the port. I am pulling 50db so I am sure there is some minor loss in the run.

 

Any advice here? 


Tek
EG
Expert

Re: What are normal signal levels?

I would experiment and put the modem on the -3.5 port of the first splitter and the second splitter on a -7dB port of the first splitter and see how the performance of everthing is Be advised that this may be too much loss for the TV stuff but you won't know until you try the test.

 

Or you could get a zero loss drop amplifier that also has what they call an *active return*. This type boosts the upstream which is what is needed in your case. You can purchase one at retail but it is Comcast that actually should supply it for free if you can convince a premises tech that that is what is needed.



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Tek
Problem Solver

Re: What are normal signal levels?

@EG the two boxes on the second split are the ones without tuners that use the XG1v4 to work. I believe they are called XiD X1. Correct me if I am wrong, but I thought those boxes use MoCA to connect to the main box and do not care about outside signal levels?

 

SIGNALS AFTER CHANGING SPLITTER: https://imgur.com/a/1RkREd2


Tek
EG
Expert

Re: What are normal signal levels?

Nice ! Now there is a bit of wiggle room on the upstream power. Hope it's enough when the warmer weather comes. The downstream of course is a bit stronger as well. Bottom line. Live with it and see. Take care.



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Tek
Problem Solver

Re: What are normal signal levels?

I can't make it any better. Connected to the tap at the pole and at the amp is sending 42/43 upstream per the Xfinity Line Technician. So unless they make a splitter with 0 loss then I can't get any better than 47 up.

Tek
EG
Expert

Re: What are normal signal levels?

Yes. They do make a zero loss amp / splitter. But 47dB isn't bad if it remains stable. As I said, live with it and see.



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