Gig1 Fibre self install - low power levels and inconsistent speeds

[acrelle]

Hi, upgraded to Gig1 fibre last week, but getting low power levels reported in the hub, the lowest power is a touch below -7.

Is there any way this can be checked remotely? I've seen in some posts that the 3.1 downstream at QAM2048 might be a sign that there may be interference on the line?

Just ran 3 samknows realspeed tests in a row. Speed to virgin media hub was 395, 889, 380.

3.0 Downstream channels

Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
25	331000000	-2.700001	38.605377	QAM256	25
10	211000000	-1.400002	38.983261	QAM256	10
11	219000000	-2.000000	38.605377	QAM256	11
12	227000000	-2.099998	38.983261	QAM256	12
13	235000000	-2.500000	38.983261	QAM256	13
14	243000000	-2.099998	38.983261	QAM256	14
15	251000000	-2.400002	38.983261	QAM256	15
16	259000000	-2.200001	38.605377	QAM256	16
17	267000000	-2.099998	38.983261	QAM256	17
18	275000000	-2.000000	38.983261	QAM256	18
19	283000000	-2.200001	38.983261	QAM256	19
20	291000000	-1.599998	38.605377	QAM256	20
21	299000000	-1.299999	38.605377	QAM256	21
22	307000000	-1.400002	38.983261	QAM256	22
23	315000000	-2.200001	38.605377	QAM256	23
24	323000000	-2.500000	38.983261	QAM256	24
26	339000000	-2.599998	38.983261	QAM256	26
27	347000000	-2.900002	38.605377	QAM256	27
28	355000000	-3.400002	38.605377	QAM256	28
29	363000000	-3.099998	38.983261	QAM256	29
30	371000000	-3.000000	38.983261	QAM256	30
31	379000000	-3.700001	38.983261	QAM256	31
32	387000000	-4.599998	38.983261	QAM256	32
33	395000000	-5.299999	38.605377	QAM256	33
34	403000000	-5.400002	37.636276	QAM256	34
35	411000000	-5.500000	38.605377	QAM256	35
36	419000000	-5.799999	38.605377	QAM256	36
37	427000000	-6.000000	38.605377	QAM256	37
38	435000000	-7.099998	37.636276	QAM256	38
39	443000000	-6.200001	38.983261	QAM256	39
40	451000000	-6.099998	38.983261	QAM256	40

3.0 Downstream channels

Channel	Lock Status	RxMER (dB)	Pre RS Errors	Post RS Errors
25	Locked	38.605377	0	0
10	Locked	38.983261	0	0
11	Locked	38.605377	0	0
12	Locked	38.983261	0	0
13	Locked	38.983261	0	0
14	Locked	38.983261	0	0
15	Locked	38.983261	0	0
16	Locked	38.605377	0	0
17	Locked	38.983261	0	0
18	Locked	38.983261	0	0
19	Locked	38.983261	0	0
20	Locked	38.605377	0	0
21	Locked	38.605377	0	0
22	Locked	38.983261	0	0
23	Locked	38.605377	0	0
24	Locked	38.983261	0	0
26	Locked	38.983261	0	0
27	Locked	38.605377	0	0
28	Locked	38.605377	0	0
29	Locked	38.983261	0	0
30	Locked	38.983261	0	0
31	Locked	38.983261	0	0
32	Locked	38.983261	0	0
33	Locked	38.605377	0	0
34	Locked	37.636276	0	0
35	Locked	38.605377	0	0
36	Locked	38.605377	0	0
37	Locked	38.605377	0	0
38	Locked	37.636276	0	0
39	Locked	38.983261	0	0
40	Locked	38.983261	0	0

3.1 Downstream channels

Channel	Channel Width (MHz)	FFT Type	Number of Active Subcarriers	Modulation (Active Profile)	First Active Subcarrier (Hz)
41	96	4K	1880	QAM2048	759

3.1 Downstream channels

Channel ID	Lock Status	RxMER Data (dB)	PLC Power (dBmV)	Correcteds (Active Profile)	Uncorrectables (Active Profile)
41	Locked	34	-14.8	13130359	36

[Andrew-G]

You've diagnosed your own problem, I've marked that for a staff response - they'll book you a technician unless the cause is a known area fault that's already being worked on.

[Ashleigh_C · Accepted solution]

Hi there @acrelle 

Thank you so much for your post and I am so sorry to hear that you have faced these issues! 

It does appear that there are a few issues showing on our side here as well, for that reason I think it would be best if we arranged for an engineer to look into this for you! 

I will send you a PM now so we can arrange it. Please keep an eye out for the purple envelope in the top right corner of your screen alerting you to a new message. 

Thank you. 

[acrelle]

PM received, thank you 🙂

[acrelle]

Hi, things have improved. Much thanks to those who helped!

So took a couple of engineer visits to get this sorted, the problem resided somewhere between the street cabinet and hub.

If I understood correctly, there was a ~15dBm loss in the cable that runs from the roadside connection at my house, and the Hub. This cable was old and that had been laid underneath a patio, with a three way splitter in a box that was partially submerged. New cable was the solution when the splitter couldn't be accessed and removed by the engineers. 

Modem stats after the work took place.

3.0 Downstream channels

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

21	299000000	7.500000	40.366287	QAM256	21
10	211000000	6.900002	38.983261	QAM256	10
11	219000000	6.500000	38.605377	QAM256	11
12	227000000	6.400002	38.605377	QAM256	12
13	235000000	6.099998	38.605377	QAM256	13
14	243000000	6.199997	38.983261	QAM256	14
15	251000000	6.199997	38.983261	QAM256	15
16	259000000	6.400002	40.366287	QAM256	16
17	267000000	6.599998	40.366287	QAM256	17
18	275000000	6.699997	40.366287	QAM256	18
19	283000000	6.699997	40.366287	QAM256	19
20	291000000	6.900002	40.366287	QAM256	20
22	307000000	7.500000	40.366287	QAM256	22
23	315000000	7.199997	40.366287	QAM256	23
24	323000000	6.599998	38.983261	QAM256	24
25	331000000	6.699997	40.366287	QAM256	25
26	339000000	6.599998	40.946209	QAM256	26
27	347000000	6.599998	40.366287	QAM256	27
28	355000000	6.400002	40.366287	QAM256	28
29	363000000	6.300003	40.366287	QAM256	29
30	371000000	5.800003	38.983261	QAM256	30
31	379000000	5.500000	38.983261	QAM256	31
32	387000000	5.099998	38.983261	QAM256	32
33	395000000	4.500000	38.983261	QAM256	33
34	403000000	4.400002	38.983261	QAM256	34
35	411000000	4.199997	38.983261	QAM256	35
36	419000000	4.099998	38.983261	QAM256	36
37	427000000	4.300003	38.983261	QAM256	37
38	435000000	4.000000	38.983261	QAM256	38
39	443000000	4.099998	40.946209	QAM256	39
40	451000000	4.000000	38.983261	QAM256	40

3.0 Downstream channels

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

21	Locked	40.366287	0	0
10	Locked	38.983261	0	0
11	Locked	38.605377	0	0
12	Locked	38.605377	0	0
13	Locked	38.605377	0	0
14	Locked	38.983261	0	0
15	Locked	38.983261	0	0
16	Locked	40.366287	0	0
17	Locked	40.366287	0	0
18	Locked	40.366287	0	0
19	Locked	40.366287	0	0
20	Locked	40.366287	0	0
22	Locked	40.366287	0	0
23	Locked	40.366287	0	0
24	Locked	38.983261	0	0
25	Locked	40.366287	0	0
26	Locked	40.946209	0	0
27	Locked	40.366287	0	0
28	Locked	40.366287	0	0
29	Locked	40.366287	0	0
30	Locked	38.983261	0	0
31	Locked	38.983261	0	0
32	Locked	38.983261	0	0
33	Locked	38.983261	0	0
34	Locked	38.983261	0	0
35	Locked	38.983261	0	0
36	Locked	38.983261	0	0
37	Locked	38.983261	0	0
38	Locked	38.983261	0	0
39	Locked	40.946209	0	0
40	Locked	38.983261	0	0

[acrelle]

Hi,

Thanks all for the help. Took a couple of engineer visits to resolve, but power levels are normal and monitoring speeds now.

There was an old cable that had been laid under a patio. This had a three way splitter in a box that couldn't be access. A new cable was laid to prevent a 15 dBm loss that was happening between the roadside connection point and the Hub.

New modem stats

3.0 Downstream channels

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

21	299000000	7.500000	40.366287	QAM256	21
10	211000000	6.900002	38.983261	QAM256	10
11	219000000	6.500000	38.605377	QAM256	11
12	227000000	6.400002	38.605377	QAM256	12
13	235000000	6.099998	38.605377	QAM256	13
14	243000000	6.199997	38.983261	QAM256	14
15	251000000	6.199997	38.983261	QAM256	15
16	259000000	6.400002	40.366287	QAM256	16
17	267000000	6.599998	40.366287	QAM256	17
18	275000000	6.699997	40.366287	QAM256	18
19	283000000	6.699997	40.366287	QAM256	19
20	291000000	6.900002	40.366287	QAM256	20
22	307000000	7.500000	40.366287	QAM256	22
23	315000000	7.199997	40.366287	QAM256	23
24	323000000	6.599998	38.983261	QAM256	24
25	331000000	6.699997	40.366287	QAM256	25
26	339000000	6.599998	40.946209	QAM256	26
27	347000000	6.599998	40.366287	QAM256	27
28	355000000	6.400002	40.366287	QAM256	28
29	363000000	6.300003	40.366287	QAM256	29
30	371000000	5.800003	38.983261	QAM256	30
31	379000000	5.500000	38.983261	QAM256	31
32	387000000	5.099998	38.983261	QAM256	32
33	395000000	4.500000	38.983261	QAM256	33
34	403000000	4.400002	38.983261	QAM256	34
35	411000000	4.199997	38.983261	QAM256	35
36	419000000	4.099998	38.983261	QAM256	36
37	427000000	4.300003	38.983261	QAM256	37
38	435000000	4.000000	38.983261	QAM256	38
39	443000000	4.099998	40.946209	QAM256	39
40	451000000	4.000000	38.983261	QAM256	40

3.0 Downstream channels

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

21	Locked	40.366287	0	0
10	Locked	38.983261	0	0
11	Locked	38.605377	0	0
12	Locked	38.605377	0	0
13	Locked	38.605377	0	0
14	Locked	38.983261	0	0
15	Locked	38.983261	0	0
16	Locked	40.366287	0	0
17	Locked	40.366287	0	0
18	Locked	40.366287	0	0
19	Locked	40.366287	0	0
20	Locked	40.366287	0	0
22	Locked	40.366287	0	0
23	Locked	40.366287	0	0
24	Locked	38.983261	0	0
25	Locked	40.366287	0	0
26	Locked	40.946209	0	0
27	Locked	40.366287	0	0
28	Locked	40.366287	0	0
29	Locked	40.366287	0	0
30	Locked	38.983261	0	0
31	Locked	38.983261	0	0
32	Locked	38.983261	0	0
33	Locked	38.983261	0	0
34	Locked	38.983261	0	0
35	Locked	38.983261	0	0
36	Locked	38.983261	0	0
37	Locked	38.983261	0	0
38	Locked	38.983261	0	0
39	Locked	40.946209	0	0
40	Locked	38.983261	0	0