Question about Signal Levels

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I'm a Reliable Contributor
Posts: 372

Question about Signal Levels

I had a look at my signal levels and see the following:

 

Downstream Overview
Port ID Frequency (MHz) Modulation Signal strength (dBmV) Channel ID Signal noise ratio (dB)
1 657000000 256QAM 2.300 17 36.387
2 561000000 256QAM 3.100 2 35.780
3 567000000 256QAM 2.500 3 35.595
4 573000000 256QAM 3.600 4 35.780
5 579000000 256QAM 4.400 5 35.780
6 585000000 256QAM 4.900 6 36.387
7 591000000 256QAM 6.300 7 36.387
8 597000000 256QAM 6.500 8 37.356
9 603000000 256QAM 6.200 9 36.610
10 609000000 256QAM 5.000 10 36.387
11 615000000 256QAM 3.700 11 36.610
12 621000000 256QAM 2.600 12 35.780
13 633000000 256QAM 2.800 13 35.780
14 639000000 256QAM 3.400 14 36.387
15 645000000 256QAM 4.000 15 35.780
16 651000000 256QAM 2.800 16 36.387
17 555000000 256QAM 3.800 1 35.780
18 663000000 256QAM 3.000 18 35.780
19 669000000 256QAM 3.300 19 35.780
20 675000000 256QAM 3.300 20 36.387
21 681000000 256QAM 3.700 21 36.387
22 687000000 256QAM 3.700 22 36.610
23 693000000 256QAM 2.900 23 36.610
24 699000000 256QAM 2.900 24 36.387
25 705000000 256QAM 2.000 25 35.780
26 711000000 256QAM 1.000 26 35.780
27 717000000 256QAM 0.100 27 35.780
28 723000000 256QAM -1.100 28 34.926
29 825000000 256QAM 0.900 29 35.595
30 831000000 256QAM 0.400 30 35.780
31 837000000 256QAM 0.000 31 35.780
32 843000000 256QAM -0.300 32 35.595
OFDM Downstream Overview
Receiver FFT type Subcarr 0 Frequency(MHz) PLC locked NCP locked MDC1 locked PLC power(dBmv)
0 NA NA NO NO NO NA
1 4K 275600000 YES YES YES 8.400002
Upstream Overview
Port ID Frequency (MHz) Modulation Signal strength (dBmV) Channel ID Bandwidth
1 38595687 ATDMA - 64QAM 39.250 3 3200000
2 30596000 ATDMA - 64QAM 35.250 1 6400000
3 23700000 ATDMA - 64QAM 33.500 2 6400000
OFDM/OFDMA Overview
Channel Index State lin Digital Att Digital Att BW (sc's*fft) Report Power Report Power1_6 FFT Size
0 DISABLED 0.5000 0.0000 0.0000 -inf -1.0000 4K
1 DISABLED 0.5000 0.0000 0.0000 -inf -1.0000 4K

 

Is it normal to have the Channel ID not equal the Port ID?  I am seeing channel 1/17 and port ID numbers flipped.

 

 

***Edited Labels***

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Posts: 1,106

Re: Question about Signal Levels

@Alex4161 It is normal that the channel ID and channel number don't match, nothing to worry about.

This is my signal levels for example, notice my upload levels:

1 591000000 256QAM -2.600 31  38.605
2 363000000 256QAM -1.000 10  38.983
3 369000000 256QAM -1.000 11  38.605
4 375000000 256QAM -0.800 12  38.983
5 381000000 256QAM -0.900 13  38.983
6 387000000 256QAM -1.200 14  38.605
7 393000000 256QAM -0.600 15  38.983
8 399000000 256QAM -1.300 16  38.605
9 405000000 256QAM -1.200 17  38.605
10 411000000 256QAM -1.100 18  40.366
11 417000000 256QAM -0.900 19  38.983
12 423000000 256QAM -0.800 20  38.983
13 429000000 256QAM -0.800 21  38.983
14 435000000 256QAM -0.700 22  38.983
15 441000000 256QAM -0.600 23  38.983
16 447000000 256QAM -0.500 24  40.946
17 555000000 256QAM -2.300 25  38.605
18 561000000 256QAM -1.800 26  38.983
19 567000000 256QAM -1.600 27  38.983
20 573000000 256QAM -1.500 28  38.983
21 579000000 256QAM -1.800 29  38.605
22 585000000 256QAM -2.200 30  38.983
23 357000000 256QAM -1.200 9  38.983
24 597000000 256QAM -3.200 32  38.983
25 825000000 256QAM -4.300 53  38.605
26 831000000 256QAM -4.600 54  37.636
27 837000000 256QAM -4.900 55  37.636
28 843000000 256QAM -4.800 56  38.605
29 633000000 256QAM -2.700 37  38.983
30 639000000 256QAM -2.800 38  38.983
31 645000000 256QAM -2.000 39  38.983
32          651000000           256QAM             -1.800          40          38.605
OFDM Downstream Overview
Receiver FFT type Subcarr 0 Frequency(MHz) PLC locked NCP locked MDC1 locked PLC power(dBmv)
0 NA NA NO NO NO NA
1 NA NA NO NO NO NA
Upstream Overview
Port ID Frequency (MHz) Modulation Signal strength (dBmV) Channel ID Bandwidth
1 30596000 ATDMA - 64QAM 27.250 1 6400000
2 38596000 ATDMA - 64QAM 30.500 3 3200000
3 23700000 ATDMA - 64QAM 27.250 2 6400000
OFDM/OFDMA Overview
Channel Index State lin Digital Att Digital Att BW (sc's*fft) Report Power Report Power1_6 FFT Size
0 DISABLED 0.5000 0.0000 0.0000 -inf -1.0000 4K
1 DISABLED 0.5000 0.0000 0.0000 -inf -1.0000 4K


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Posts: 372

Re: Question about Signal Levels

Thanks for the fast reply.  I wish I had your s/n levels 🙂

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Posts: 8

Re: Question about Signal Levels

Experiencing intermittent issues and CODA-4582U DOCSIS event logs display frequently occuring T3-time-outs.

 

I read somewhere the optimal Signal strength (dBmV) for DownStream is between - 10 dBmV to + 10 dBmV and ideally at 0dBmV with SNR 36~40 dB range with UpStream normally 36~51 dBmV.

 

Opened several cases with Rogers but CSR avoids addressing my signal levels and critical error logs.   Past posts recommend upgrade of equipment at the headend but if I am the only one complaining no one is listening.  Please advise.

 

17 03/15/2020 09:06:11 84000500 critical SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:17:10:90:cc:8b;CM-QOS=1.1;CM-VER=3.1;
18 03/15/2020 16:43:50 82000200 critical No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:17:10:90:cc:8b;CM-QOS=1.1;CM-VER=3.1;
19 03/16/2020 13:28:32 90000000 warning MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:17:10:90:cc:8b;CM-QOS=1.1;CM-VER=3.1;
20 03/16/2020 21:47:02 82000200 critical No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:17:10:90:cc:8b;CM-QOS=1.1;CM-VER=3.1;

 

 

 

Downstream Overview
Port ID Frequency (MHz) Modulation Signal strength (dBmV) Channel ID Signal noise ratio (dB)
1 591000000 256QAM 11.100 7 40.366
2 849000000 256QAM 12.400 2 40.366
3 855000000 256QAM 13.000 3 40.366
4 861000000 256QAM 12.800 4 40.366
5 579000000 256QAM 10.400 5 38.605
6 585000000 256QAM 10.700 6 38.983
7 279000000 256QAM 10.600 1 37.356
8 597000000 256QAM 10.900 8 38.983
9 603000000 256QAM 10.400 9 40.366
10 609000000 256QAM 10.200 10 38.605
11 615000000 256QAM 10.000 11 38.983
12 621000000 256QAM 9.800 12 38.983
13 633000000 256QAM 8.900 13 38.605
14 639000000 256QAM 8.900 14 38.983
15 645000000 256QAM 9.500 15 38.605
16 651000000 256QAM 9.400 16 38.983
17 657000000 256QAM 9.100 17 37.636
18 663000000 256QAM 8.900 18 38.983
19 669000000 256QAM 8.400 19 37.636
20 675000000 256QAM 8.600 20 37.356
21 681000000 256QAM 9.300 21 38.605
22 687000000 256QAM 9.600 22 38.605
23 693000000 256QAM 9.700 23 38.983
24 699000000 256QAM 9.400 24 38.605
25 705000000 256QAM 9.000 25 38.605
26 711000000 256QAM 9.100 26 38.605
27 717000000 256QAM 8.900 27 38.605
28 723000000 256QAM 8.700 28 38.605
29 825000000 256QAM 11.600 29 38.983
30 831000000 256QAM 11.900 30 40.366
31 837000000 256QAM 12.400 31 40.366
32 843000000 256QAM 11.900 32 40.366
OFDM Downstream Overview
Receiver FFT type Subcarr 0 Frequency(MHz) PLC locked NCP locked MDC1 locked PLC power(dBmv)
0 NA NA NO NO NO NA
1 4K 275600000 YES YES YES 10.300003
Upstream Overview
Port ID Frequency (MHz) Modulation Signal strength (dBmV) Channel ID Bandwidth
1 30596000 ATDMA - 64QAM 26.000 7 6400000
2 36996000 ATDMA - 64QAM 27.250 8 6400000
3 22100000 ATDMA - 64QAM 28.500 5 3200000
4 25300000 ATDMA - 64QAM 28.750 6 3200000
OFDM/OFDMA Overview
Channel Index State lin Digital Att Digital Att BW (sc's*fft) Report Power Report Power1_6 FFT Size
0 DISABLED 0.5000 0.0000 0.0000 -inf -1.0000 4K
1 DISABLED 0.5000 0.0000 0.0000 -inf -1.0000 4K
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Posts: 6,755

Re: Question about Signal Levels

@JSS_BRAMPTON your downstream DOCSIS 3.0 (chan 1 to 32) signal levels are too high, even by Rogers standards.  The signal to noise ratios are fine as are the QAM levels. 

 

The upstream DOCSIS 3.0 channels are a little low compared to what we normally see, however, if you're in an apartment/condo/highrise or in a house that is very close to the neighbourhood node, those levels would make sense.  

 

The Downstream DOCSIS 3.1 OFDM channel would also be running at a very high level, but, the actual aggregated signal level, QAM level and signal to noise ratios are not presented in the user interface.  Tech support has access to that data, so you would have to ask tech support specifically if the OFDM signal level, QAM level and signal to noise ratio were within spec.  The QAM level should e at 1024 for this modem when the signal levels and signal to noise ratios are within acceptable ranges. 

 

If the Customer Service Rep ran an signal check on the modem, that would produce a pass/fail indication, but, you would have specifically ask the CSR to check the OFDM data.  

 

Fwiw, I refer you to the following thread regarding latency and packet loss that has been observed on the Rogers network over the last two months:

 

https://communityforums.rogers.com/t5/Internet/Brutal-latency-ping-Recently/td-p/454780

 

This is an ongoing problem where Rogers is completely silent as to the cause and any potential changes to correct the situation.  There are hundreds (?) of complaints in that thread, in a corresponding reddit thread and direct complaints from most if not all of the TPIAs that use Rogers network, to no avail I would say.  This might explain the problems that you are currently seeing, beyond anything that might be occurring due to your signal levels. 

 

Personal opinion, you need a tech to install a 9 dB attenuator to drop the downstream signal levels.  That will cause the upstream levels to rise by the same amount, but, after the attenuator, the outbound signal levels will be the same, and that will probably be fine as the outbound signal levels are controlled by the Cable Modem termination System (CMTS), so, if they needed to run at at higher level, the CMTS would command the modem to run at a higher output level. 

 

Edit:  a DOCSIS 3.0 modem on the Rogers network will typically run at 36 to 40 dBmV for upstream transmit power levels.  The 4582 historically runs in the 30 to 32 dBmV range, so your upstream signal levels are a little low, but, they might be absolutely fine if the signal level and signal to noise ratios at the arriving end (neighbourhood node) are ok.  



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Re: Question about Signal Levels

Thank you for your enlightenment. The Rogers utility box is right outside my home. Today I was lucky to get a CSR who noted signal issues and opened a ticket to dispatch another tech to troubleshoot issues outside. I will make a note of your recommendations and share with the tech. Thank you.
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Re: Question about Signal Levels

The tech will be able to access the modem signal levels before he or she arrives at your home.  His or her immediate thought should be to drop the downstream signal levels down to 0 dBmV.  A 9 dB attenuator will almost achieve that so that your downstream signal levels end up with a -0.4 to 4 dBmV range.   That's not too bad. 

 

A normal attenutor will also drive up the outbound signal levels by the same amount.  In your case, that won't be an issue. 

 

There is a Forward Path Attenuator that can be used to drop the downstream signal levels while leaving the upstream signal levels as they are.  I don't know if Rogers uses the Forward Path Attenuators or if they stick to the typical attenuators that are used throughout the industry.  



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Re: Question about Signal Levels

Wanted to know if my signals are fine. I've been having major ping issues and packet loss while pinging Rogers' primary DNS (Approx. 21%).

 

Downstream Overview
Port IDFrequency (MHz)ModulationSignal strength (dBmV)Channel IDSignal noise ratio (dB)
1615000000256QAM7.3001140.366
2603000000256QAM7.100940.366
3609000000256QAM7.2001040.366
4597000000256QAM7.000840.366
5279000000256QAM13.300143.377
6579000000256QAM7.700540.366
7585000000256QAM7.500640.946
8591000000256QAM7.500740.366
9621000000256QAM7.6001240.366
10633000000256QAM6.8001340.366
11639000000256QAM6.6001440.366
12645000000256QAM6.6001540.366
13651000000256QAM6.8001640.946
14657000000256QAM6.7001740.946
15663000000256QAM6.5001840.366
16669000000256QAM6.4001940.366
17675000000256QAM6.6002040.366
18681000000256QAM6.4002140.366
19687000000256QAM6.8002240.946
20693000000256QAM6.7002340.366
21699000000256QAM6.7002440.366
22705000000256QAM6.7002540.366
23711000000256QAM6.7002640.366
24717000000256QAM6.5002740.366
25723000000256QAM6.0002840.946
26825000000256QAM6.0002940.366
27831000000256QAM5.8003040.366
28837000000256QAM5.4003140.366
29843000000256QAM5.1003240.366
30849000000256QAM4.800240.366
31855000000256QAM4.800340.366
32861000000256QAM4.400440.366
OFDM Downstream Overview
ReceiverFFT typeSubcarr 0 Frequency(MHz)PLC lockedNCP lockedMDC1 lockedPLC power(dBmv)
0NANANONONONA
14K275600000YESYESYES10.800003
Upstream Overview
Port IDFrequency (MHz)ModulationSignal strength (dBmV)Channel IDBandwidth
122100000ATDMA - 64QAM21.00013200000
236996000ATDMA - 64QAM19.75046400000
330596000ATDMA - 64QAM19.50036400000
425300000ATDMA - 64QAM22.25023200000
OFDM/OFDMA Overview
Channel IndexStatelin Digital AttDigital AttBW (sc's*fft)Report PowerReport Power1_6FFT Size
0DISABLED0.50000.00000.0000-inf-1.00004K
1DISABLED0.50000.00000.0000-inf-1.0000

4K

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Re: Question about Signal Levels

@Datalink last evening I looked out and saw a Senior Rogers tech working on the tap.  I spoke to him and he was kind enough to quickly move my service through a splitter and a 6 dB attenuator. Readings improved and he recommended I swap the modem.  My tech visit is scheduled for March 19 and I am now tempted to ask the tech to replace the 6 for 9 dB attenuator, to drop the signal further, as you suggested.

 

Downstream Overview
Port IDFrequency (MHz)ModulationSignal strength (dBmV)Channel IDSignal noise ratio (dB)
1669000000256QAM5.3001934.346
2849000000256QAM8.800236.610
3855000000256QAM9.000337.356
4861000000256QAM9.000437.636
5579000000256QAM7.300535.595
6585000000256QAM7.600635.595
7591000000256QAM7.900736.387
8597000000256QAM7.700835.595
9603000000256QAM7.100935.780
10609000000256QAM7.0001035.595
11615000000256QAM7.0001135.595
12621000000256QAM7.1001235.595
13633000000256QAM5.2001333.957
14639000000256QAM3.8001433.377
15645000000256QAM4.3001533.487
16651000000256QAM4.5001633.957
17657000000256QAM4.8001733.957
18663000000256QAM5.1001833.957
19279000000256QAM7.600135.084
20675000000256QAM5.8002034.484
21681000000256QAM6.1002135.084
22687000000256QAM6.4002234.926
23693000000256QAM6.5002335.084
24699000000256QAM6.3002435.084
25705000000256QAM6.1002534.926
26711000000256QAM6.1002635.084
27717000000256QAM5.9002734.926
28723000000256QAM5.9002834.926
29825000000256QAM7.8002936.387
30831000000256QAM8.4003036.610
31837000000256QAM9.0003136.610
32843000000256QAM8.5003236.610
OFDM Downstream Overview
ReceiverFFT typeSubcarr 0 Frequency(MHz)PLC lockedNCP lockedMDC1 lockedPLC power(dBmv)
0NANANONONONA
14K275600000YESYESYES7.400002
Upstream Overview
Port IDFrequency (MHz)ModulationSignal strength (dBmV)Channel IDBandwidth
130596000ATDMA - 64QAM35.75076400000
236996000ATDMA - 64QAM35.75086400000
322100000ATDMA - 64QAM37.50053200000
425299824ATDMA - 64QAM37.25063200000
OFDM/OFDMA Overview
Channel IndexStatelin Digital AttDigital AttBW (sc's*fft)Report PowerReport Power1_6FFT Size
0DISABLED0.50000.00000.0000-inf-1.00004K
1DISABLED0.50000.00000.0000-inf-1.00004K
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Posts: 14,190

Re: Question about Signal Levels

@Taab & @JSS_BRAMPTON 

I would say BOTH of yours are on the high side.

'within spec' are + or - 10.
And both of them are getting up there or over.
Optimally should be close to 0.

So definitely would be worth getting a tech out to take a look at things.
Even just putting in a splitter, etc, which would drop down the signal level a bit.