Menu
Reply
Highlighted
  • 45
  • 0
  • 3
On our wavelength
205 Views
Message 1 of 16
Flag for a moderator

Experts - Explain to me this....

Had VM installed 4 months now, initial ds power levels were around +4 to +6 and then increased over time to around +6 to +10, that is until 4 days ago when there was an area outage and the whole area went off for "planned maintenance" When it did come back up originally, my power levels were around 0 to +1 which from what I understand, are perfect levels? It then went off again after an hour and came back and hasn't gone off since. The power levels are between +4 to +5.4 now and have been for a last few days. What causes the power levels, rise like they did originally to drop to 0 and then back to 4? 

On the upstream side on things, pre outage I was running at between 44-46db, post outage 39-41db, which I think is okay?

Anyhow, on the back of the outage and has since been settled, even though there hasn't been any issues that I have noticed, my router pre and post error counts are massive (i've reset the router to clear them but came back) and I also have T3 timeouts in the upstream window, i've not had T3 timeouts before pre outage, and I have had a handful of PRE errors on the DS before the outage which maybe 1 post error in 4 months prior.

So yeah so if anyone could let me know about my questions above. Like I said, not noticed any untoward effects so far, just curious to know why it has done what it has done!

Will post stats below...

Cable Modem StatusItem Status Comments

Acquired Downstream Channel (Hz)
355000000
Locked
Ranged Upstream Channel (Hz)
39400000
Locked
Provisioning State
Online

 

 

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

13550000004.338256 qam28
22510000005.438256 qam15
3259000000538256 qam16
42670000004.638256 qam17
52750000004.538256 qam18
62830000004.538256 qam19
72910000004.538256 qam20
82990000004.838256 qam21
93070000004.538256 qam22
103150000004.538256 qam23
113230000004.538256 qam24
123310000004.638256 qam25
133390000004.538256 qam26
143470000004.538256 qam27
153630000004.138256 qam29
163710000004.338256 qam30
173790000004.438256 qam31
183870000004.438256 qam32
193950000004.538256 qam33
204030000004.538256 qam34
214110000004.638256 qam35
224190000004.538256 qam36
234270000004.540256 qam37
24435000000438256 qam38



Downstream bonded channels

Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors

1Locked38.97792297
2Locked38.9265481091
3Locked38.9277391441
4Locked38.9304601674
5Locked38.9522481641
6Locked38.9758421715
7Locked38.9459281183
8Locked38.931037785
9Locked38.627238588
10Locked38.625492367
11Locked38.925857273
12Locked38.929700132
13Locked38.948778124
14Locked38.996290112
15Locked38.92684987
16Locked38.919397106
17Locked38.919292104
18Locked38.91892569
19Locked38.61773539
20Locked38.61604216
21Locked38.91498772
22Locked38.9145556
23Locked40.9135901
24Locked38.9144395

 

Upstream bonded channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

13940000040.3512064 qam12
23260000039.3512064 qam13
34620004140.5512064 qam11
45370000041.3512064 qam10



Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0040
2ATDMA0010
3ATDMA0000
4ATDMA0000

 

0 Kudos
Reply
Highlighted
  • 45
  • 0
  • 3
On our wavelength
204 Views
Message 2 of 16
Flag for a moderator

Re: Experts - Explain to me this....

General Configuration

Network access
Allowed
Maximum Number of CPEs
1
Baseline Privacy
Enabled
DOCSIS Mode
Docsis30
Config file
ewrkldJKDHSUBsgvca69834ncxv98



Primary Downstream Service Flow

SFID1200
Max Traffic Rate575000000
Max Traffic Burst42600
Min Traffic Rate0



Primary Upstream Service Flow

SFID1199
Max Traffic Rate38520000
Max Traffic Burst42600
Min Traffic Rate0
Max Concatenated Burst16320
Scheduling TypeBestEffort

 

15/11/2020 12:09:10noticeLAN login Success;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
13/11/2020 05:17:26criticalNo Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 18:04:10noticeDHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt053+voc-b.cm modified;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 18:04:10ErrorDHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 17:04:11noticeDHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt053+voc-b.cm modified;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 17:04:11ErrorDHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 16:34:10noticeDHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt053+voc-b.cm modified;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 16:34:10ErrorDHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 16:04:9noticeDHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt053+voc-b.cm modified;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 16:04:9ErrorDHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 15:34:9noticeDHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt053+voc-b.cm modified;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 15:34:9ErrorDHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 15:04:9noticeDHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt053+voc-b.cm modified;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 15:04:9ErrorDHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 14:34:9noticeDHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt053+voc-b.cm modified;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 14:34:9ErrorDHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 14:04:8noticeDHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt053+voc-b.cm modified;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 14:04:8ErrorDHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 13:34:8noticeDHCP Renew - lease parameters tftp file-cmreg-vmdg505-bbt053+voc-b.cm modified;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
12/11/2020 13:34:8ErrorDHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
0 Kudos
Reply
Highlighted
  • 45
  • 0
  • 3
On our wavelength
140 Views
Message 3 of 16
Flag for a moderator

Re: Experts - Explain to me this....

It was : 

13550000004.338256 qam28
22510000005.438256 qam15
3259000000538256 qam16
42670000004.638256 qam17
52750000004.538256 qam18
62830000004.538256 qam19
72910000004.538256 qam20
82990000004.838256 qam21
93070000004.538256 qam22
103150000004.538256 qam23
113230000004.538256 qam24
123310000004.638256 qam25
133390000004.538256 qam26
143470000004.538256 qam27
153630000004.138256 qam29
163710000004.338256 qam30
173790000004.438256 qam31
183870000004.438256 qam32
193950000004.538256 qam33
204030000004.538256 qam34
214110000004.638256 qam35
224190000004.538256 qam36
234270000004.540256 qam37
24435000000438256 qam38

 

Upstream bonded channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

13940000040.3512064 qam12
23260000039.3512064 qam13
34620004140.5512064 qam11
45370000041.3512064 qam10

 

 

It is now :

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

12030000007.338256 qam9
213900000010.938256 qam1
31470000001038256 qam2
41550000009.538256 qam3
5163000000938256 qam4
6171000000938256 qam5
71790000008.538256 qam6
81870000008.438256 qam7
91950000007.938256 qam8
102110000007.438256 qam10
11219000000738256 qam11
122270000006.838256 qam12
132350000006.138256 qam13
142430000005.838256 qam14
15251000000538256 qam15
162590000004.638256 qam16
172670000004.438256 qam17
182750000004.538256 qam18
192830000004.438256 qam19
202910000004.638256 qam20
212990000004.538256 qam21
223070000004.538256 qam22
233150000004.438256 qam23
243230000004.338256 qam24

 

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

13940012240.5512016 qam12
23260007340.5512016 qam13
34619999140.5512016 qam11
45370006142512032 qam10

 

 

So the power has doubled on some channels to now what is out of spec (+10?) from what I have read, and the upstream modulation has dropped from 64qam to 16qam on 3 of channels with the other at 32qam.

Doing a speed test still shows things are fine, my upload has dropped maybe 2-3mb from 35mb to 32-33mb from but not seeing the issues people usually see when their power levels are higher than normal / upstream qam levels are low, which is a good thing, but I feel like I want to understand why, its like an itch that I need to understand these things.

0 Kudos
Reply
Highlighted
  • 45
  • 0
  • 3
On our wavelength
139 Views
Message 4 of 16
Flag for a moderator

Re: Experts - Explain to me this....

Screenshot 2020-11-18 083549.jpg

0 Kudos
Reply
Highlighted
  • 5.97K
  • 1.13K
  • 1.58K
Very Insightful Person
Very Insightful Person
130 Views
Message 5 of 16
Flag for a moderator

Re: Experts - Explain to me this....

Hello

Looking at the stats and the logs you seem to have quuite a number of Post RS Errors which shows as T3 errors in the log, these can be caused by noise on the which may be resolved by doing the following please go around and make sure that all coaxial connections to all VM equipment are finger tight best way to do this is too loosen the connector and re-tighten, once checked power off the hub for 30 secs and back on, then check in your downstream again if you see the Post RS rising at a large rate then only an engineer can resolve that.

Please let the forum know the results of doing the above.

Regards Mike

I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more

Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks

0 Kudos
Reply
Highlighted
  • 45
  • 0
  • 3
On our wavelength
99 Views
Message 6 of 16
Flag for a moderator

Re: Experts - Explain to me this....

My upload speed has now taken a swan dive and my upstream QAMs are all over the place, one min they will be at 64 then 32 but at the moment they are all on 16QAM and my upload is now limited to around 12mb (rather than 34-36mb), power dbm looks okay I think, so what else might it be? 

Screenshot 2020-11-25 151606.jpg

0 Kudos
Reply
Highlighted
  • 12.06K
  • 939
  • 1.54K
Alessandro Volta
90 Views
Message 7 of 16
Flag for a moderator

Re: Experts - Explain to me this....

Can you set up a Broadband Quality Monitor (BQM) at thinkbroadband.com - this will give you an insight into what is happening with the signal at the other side of the Hub, it will take a few hours to get any kind of trend showing although you should post the link straight away.

Post a 'Live Link' to your BQM on here.

Instructions for posting BQM Link

Under your BQM graph are two links in red.

Click the lower link (Share Live Graph) then click generate.

Copy the text in the Direct Link box, beware, there may be more text than you can see.

On here click the Link icon (2 links chain to the left of the camera icon)

In the URL box paste the link you copied and in the ‘text to display’ box write My BQM then click OK - you can post the link straight away.

I think the BQM will explain the Upstream QAM issues.

***********************************************************************************************************************************

Mike Robinson
Semi-Retired Aircraft Engineer & Computer Based Training and Learning Designer for many of the world's Military Arms.

My Broadband Ping - Mike Robbo
0 Kudos
Reply
Highlighted
  • 45
  • 0
  • 3
On our wavelength
83 Views
Message 8 of 16
Flag for a moderator

Re: Experts - Explain to me this....

BQM 

My Broadband Ping - VM500

 

Setup. Its back to 64QAM now, but it will soon change again!

0 Kudos
Reply
Highlighted
  • 2.22K
  • 144
  • 430
Problem sorter
72 Views
Message 9 of 16
Flag for a moderator

Re: Experts - Explain to me this....

Sticking my neck out here.  The acceptable DS power range is -6 to +10 and US 34 to 51.  Post RS errors should be 0 or very low.

The fact your US jumps between 16QAM and 64QAM is most likely noise in the circuit, and the modem is dropping to 16QAM to cope. 

A quiet circuit should be 64QAM ( I believe there may be some areas still on 16 x 4 QAM?, as I was until recently) 

If you do as suggested and check all connections from outside to in, and they are all tight. then you will need an engineer to check the ingress and fix it.

In any case, don't over think the power levels as they also fluctuate with the outside temperature, so they are not static.

0 Kudos
Reply
Highlighted
  • 45
  • 0
  • 3
On our wavelength
47 Views
Message 10 of 16
Flag for a moderator

Re: Experts - Explain to me this....

All connections are tight, the install is only 4 months old, brand new cable pull and street works to accommodate! Stats and speeds have been good until the outage the other week for the area, and now nothing is stable. How do I get an engineer out to look at the upstream QAM?

My BQM has been running for over a day now and you can see there is alot of spiky yellow! It actually went off at 00:01am this morning and required a router reboot. Stats were just as bad post reboot at 00:01am.

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

12030000007.838256 qam9
213900000010.940256 qam1
31470000001038256 qam2
41550000009.538256 qam3
5163000000938256 qam4
61710000008.840256 qam5
71790000008.438256 qam6
81870000008.338256 qam7
9195000000840256 qam8
102110000007.538256 qam10
112190000007.440256 qam11
12227000000738256 qam12
132350000006.538256 qam13
14243000000638256 qam14
152510000005.538256 qam15
16259000000538256 qam16
172670000004.838256 qam17
182750000004.638256 qam18
192830000004.638256 qam19
202910000004.838256 qam20
212990000004.938256 qam21
223070000004.538256 qam22
233150000004.638256 qam23
243230000004.838256 qam24



Downstream bonded channels

Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors

1Locked38.6130
2Locked40.370
3Locked38.9190
4Locked38.9220
5Locked38.960
6Locked40.3100
7Locked38.940
8Locked38.970
9Locked40.360
10Locked38.9200
11Locked40.3200
12Locked38.9170
13Locked38.9240
14Locked38.960
15Locked38.960
16Locked38.9110
17Locked38.9140
18Locked38.6130
19Locked38.620
20Locked38.6150
21Locked38.9100
22Locked38.980
23Locked38.9110
24Locked38.680
0 Kudos
Reply