Virgin upgrade works has messed up power levels

[madmanx]

Hi had some work on my local network done today as it says it was doing upgrade work to improve the services, 

But after being down for half the day when the hub came back online I saw the power levels are way out if sync now. The downstream before was between 0 and 3dbmv and the upstream dbmv was about 38 dmbv, now the downstream is +10 dbmv and the upstream is now around 34dbmv, do I need an engineer to fix it? I have a 6db forward path attenuater fitted at back of hub which i could change to a 10db forward path attenuator to bring down the downstream power levels but its the upstream I'm concerned about as its only 34dbmv?

Have I a problem now?

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Downstream bonded channels

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

1	138750000	9.8	38	256 qam	1
2	146750000	9.5	38	256 qam	2
3	154750000	9.5	38	256 qam	3
4	162750000	9.5	38	256 qam	4
5	170750000	9.6	38	256 qam	5
6	178750000	9.5	38	256 qam	6
7	186750000	9.5	38	256 qam	7
8	194750000	9.6	38	256 qam	8
9	202750000	9.6	38	256 qam	9
10	210750000	9.5	38	256 qam	10
11	218750000	9.6	38	256 qam	11
12	226750000	9.6	38	256 qam	12
13	234750000	9.8	38	256 qam	13
14	242750000	9.6	38	256 qam	14
15	250750000	9.8	38	256 qam	15
16	258750000	9.8	38	256 qam	16
17	266750000	10	38	256 qam	17
18	274750000	9.8	38	256 qam	18
19	282750000	9.8	38	256 qam	19
20	290750000	9.8	38	256 qam	20
21	298750000	10	38	256 qam	21
22	306750000	10	38	256 qam	22
23	314750000	10	38	256 qam	23
24	322750000	10.1	38	256 qam	24

Downstream bonded channels

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

1	Locked	38.9	6	0
2	Locked	38.6	6	0
3	Locked	38.6	6	0
4	Locked	38.9	5	0
5	Locked	38.6	7	0
6	Locked	38.6	5	0
7	Locked	38.6	18	0
8	Locked	38.9	15	0
9	Locked	38.9	5	0
10	Locked	38.9	6	0
11	Locked	38.6	4	0
12	Locked	38.9	7	0
13	Locked	38.9	5	0
14	Locked	38.9	5	0
15	Locked	38.9	4	0
16	Locked	38.6	5	0
17	Locked	38.6	6	0
18	Locked	38.6	4	0
19	Locked	38.9	5	0
20	Locked	38.9	6	0
21	Locked	38.6	6	0
22	Locked	38.9	5	0
23	Locked	38.9	5	0
24	Locked	38.9	5	0

[Matthew_ML]

Hey madmanx, thank you for reaching out and I am sorry to hear about this.

I can see you've spoken to the team about this, did they manage to help at all?

[madmanx]

Hi seph I managed to lift cover up it's full of mud will post photo

 

[Sephiroth]

Is that wet mud?  The photo has to be approved by someone and that might take a while.  Wet mud can cause electrolytic effects - depends on how well insulated the cables and connectors are.  Water is much worse than mud, though.  This is stuff to tell the tech when he/she arrives.

[madmanx]

Hi seph yeah the mud is damp not soaking wet though, hopefully moderator will approve photo soon so u can see it, it's been raining for couple of days and as expected the upstream qam on the lowest frequency has dropped to 16qam.

[madmanx]

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Router status

• Status
• Downstream
• Upstream
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Refresh data

Upstream bonded channels

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

1	23600033	34.2	5120	16 qam	5
2	36600167	34.5	5120	64 qam	3
3	43100000	34.8	5120	64 qam	2
4	30100000	34.5	5120	64 qam	4
5	49599966	35	5120	64 qam	1

Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1	ATDMA	0	0	5	0
2	ATDMA	0	0	7	0
3	ATDMA	0	0	3	0
4	ATDMA	0	0	2	0
5	ATDMA	0	0	2	0

[Sephiroth]

I assume that you're right near the VM cabinet (which explains the power levels).   If the upstream noise isn't coming from micro-reflections in the drop point, then something in the cabinet is getting et.  The technician should know what to check.  Rain seems to be the simultaneous factor.

Fitting an attenuator of any sort won't fix this (sometimes they try to bring downstream power down when that isn't needed and if they fit a fat attenuator, it pushes up the upstream power and that still won't help.  All notions of power 'sweet spots' are relevant only in perfect line conditions.

[madmanx]

Hi the cabinet is about 100 ,meters away I will post another photo its not that near, are u saying the tech shouldn't lower the power levels? The downstream stream is over 10dbmv

[Sephiroth]

You don't have any post-RS errors (is that still the case?) - so downstream is OK.  The upstream power is commanded by the CMTS and set at the value it needs to read the upstream data.  This can dynamically change at any time.  If there is noise on the line, the QAM modulation will be changed by the CMTS.

When it rains, according to my understanding of your issue, the QAM modulation on upstream falls and you have a bad internet experience.  So something is getting wet and causing noise ingress on the upstream.

Any neighbours with the same issue?  A very useful piece of knowledge that would be.

[Sephiroth]

Btw, wrt to your high power - you will have been placed on a low attenuation tap point at the cabinet.  My sticky post on power level explains all that.

[madmanx]