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NChannon
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Millions of Pre-RS errors

For a while now I've had "funny" net issues but it's been hard to diagnose because some connections seem to be fine, but after reading a few forums posts I noticed that my hub stats aren't great...

My set-up is SH3 in modem mode. Router Status logs below are at the end of this message but the short version is I think the downstream power levels are too high, the SNR is too low and we're getting hundreds of millions of Pre-RS errors (quite literally, uptime of 24 hours can be into 500,000,000 errors) and although Post-RS errors are zero,  Ithink this is hindering the hub's performance somewhat because we just have strange net activity.

One thing that's really strange is that for the life of me I am unable to get in contact with anybody about this - I hate the UK telecoms industry for support, they've just got it all wrong, absolutely horrendous.

I'm hoping for someone from @virgin to help/arrange a tech visit to get this sorted as I rely upon it for work and I'm worried it's about to die completely.

Logs (No network log as it's pretty empty) - I think upstream looks OK?

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

12990000009.332256 qam21
213900000012.332256 qam1
314700000012.132256 qam2
415500000012.432256 qam3
516300000012.332256 qam4
617100000012.532256 qam5
717900000012.433256 qam6
818700000012.532256 qam7
919500000011.932256 qam8
1020300000011.533256 qam9
1121100000011.432256 qam10
1221900000010.932256 qam11
1322700000010.932256 qam12
1423500000010.332256 qam13
1524300000010.432256 qam14
162510000009.932256 qam15
172590000009.932256 qam16
182670000009.532256 qam17
192750000009.632256 qam18
202830000009.432256 qam19
212910000009.532256 qam20
223070000009.332256 qam22
233150000009.132256 qam23
243230000008.932256 qam24



Downstream bonded channels

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

1Locked32.2500624240
2Locked32.6509093530
3Locked32.6533789830
4Locked32.6531203400
5Locked32.6493419810
6Locked32.6457839630
7Locked33420129310
8Locked32.9406038320
9Locked32.9376052660
10Locked33373152480
11Locked32.9369499760
12Locked32.9378321750
13Locked32.5399646060
14Locked32.6420613430
15Locked32.5394354970
16Locked32.6390656260
17Locked32.3459734720
18Locked32.3466651680
19Locked32.5429400020
20Locked32.3457163200
21Locked32.2478337910
22Locked32.2500644080
23Locked32.3471648560
24Locked32.2503380860

 

Upstream bonded channels

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

13940000937.8512064 qam2
22579999137.8512064 qam4
33260000937.8512064 qam3
44620002939512064 qam1



Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1ATDMA0000
2ATDMA0000
3ATDMA0000
4ATDMA0000

 

 

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MikeRobbo
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Alessandro Volta
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Message 2 of 12
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Helpful Answer

Re: Millions of Pre-RS errors

Several of your Downstream Power Levels are too high and will need an engineer visit to put them right.

You can either phone in (08:00 is the best time) or wait on here for a few days until one of the VM Forum Staff comes along.

++++++++++++++++++++++++++++++++++++++++++++++

To clear the Pre RS Error count try a reboot using this method ...

Switch the Hub off using the small switch on the rear of the Hub next to the power cord and pull the PSU plug from the wall socket.

Give it a good 5 minutes put the plug back in and switch the Hub back on.

Allow the Hub a few minutes to fully restart then check your error count again.


*********************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************
BT Smart Hub 2 with 70Mbs Download,18Mbs Upload, 9.17ms Latency & 0.35ms Jitter.
NChannon
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Message 3 of 12
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Re: Millions of Pre-RS errors

Thank you for the response. I keep rebooting once a day to keep the errors from going beyond a number that might crash the hub!

I'll try the phone again, it seems to be an infinte loops of pressing numbers on the handset until you give up and put it down though... I'm glad you agree on the levels though. Do you also agree the SNR is too low?

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jem101
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Re: Millions of Pre-RS errors

Yes they are too low across the board.

NChannon
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Re: Millions of Pre-RS errors

Going to close this off as I now have an egineer booked.

 

Thanks all.

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Lee_R
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Message 6 of 12
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Re: Millions of Pre-RS errors

Hi NChannon

Did the tech visit resolve your issue?

Regards


Lee_R

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NChannon
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Re: Millions of Pre-RS errors

Hi - yes and no. The downstream power levels were fixed with an attenuator, but the SNR is still low. I didn't realise, but the engineer confirmed we had 1GB available in my area so I ordered that, and have installed the SH4. It's all working, but I still see SNR is a little low, and that there's a big spread on power values for the downstream, so we're still seeing millions of Pre-RS errors - but only the odd Post-RS errors (virtually none really, might be 1 per day).

My download hasn't hit the magical 1GB yet but I think that's possibly because of the noise? I'm honestly not sure.

Values in next post because of the char limit.

 

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NChannon
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Re: Millions of Pre-RS errors

3.0 Downstream channels

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

263390000002.59999832.237156QAM25626
11390000007.50000033.376591QAM2561
21470000007.59999833.376591QAM2562
31550000007.09999833.376591QAM2563
41630000007.00000033.062504QAM2564
51710000006.90000233.376591QAM2565
61790000006.80000333.486542QAM2566
71870000006.59999833.376591QAM2567
81950000006.50000033.376591QAM2568
92030000006.19999733.376591QAM2569
102110000006.00000033.486542QAM25610
112190000005.69999733.376591QAM25611
122270000005.40000232.962662QAM25612
132350000005.00000032.962662QAM25613
142430000004.90000233.062504QAM25614
152510000004.59999832.962662QAM25615
162590000004.19999732.584778QAM25616
172670000004.09999832.584778QAM25617
182750000004.40000232.962662QAM25618
192830000004.19999732.676208QAM25619
202910000004.09999832.584778QAM25620
212990000003.79999932.584778QAM25621
223070000003.29999932.676208QAM25622
233150000003.09999832.676208QAM25623
243230000002.79999932.584778QAM25624
253310000002.70000132.321487QAM25625
273470000002.50000031.993563QAM25627
283550000002.20000131.915308QAM25628
293630000002.20000131.993563QAM25629
303710000002.20000131.993563QAM25630
313790000002.20000132.237156QAM25631



3.0 Downstream channels

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

26Locked01404760
1Locked4283837781087510
2Locked4317211361083950
3Locked4187594041095210
4Locked4303451851027750
5Locked2995379243954700
6Locked2980500048889040
7Locked431157052863120
8Locked296132830839670
9Locked295841205826220
10Locked296408939795300
11Locked296100823847760
12Locked295016195899520
13Locked294352626955820
14Locked293876267875910
15Locked294546038923850
16Locked2942724831006180
17Locked2958036881030250
18Locked295155497942190
19Locked2962273781030080
20Locked2882703301037010
21Locked2921314401053110
22Locked2950216031115010
23Locked2950497491034190
24Locked3893176971106660
25Locked4184156351205470
27Locked4271071801569610
28Locked4270432091674250
29Locked4277659441600730
30Locked4269170411618670
31Locked30430056561536670



3.1 Downstream channelsChannel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)
159804K1560QAM2048392


3.1 Downstream channelsChannel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)
159Locked 2.0347201290

 

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Tudor
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Message 9 of 12
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Re: Millions of Pre-RS errors

Just for your information Pre RS error are error that have been corrected, Post RS error are uncorrectable error. Of course correcting the errors does slow down your connection.


Tudor
There are 10 types of people: those who understand binary and those who don't and F people out of 10 who do not understand hexadecimal c1a2a285948293859940d9a49385a2
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NChannon
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Re: Millions of Pre-RS errors

Hey @Tudor - yeah I understand that but I don't know what the norm is or if there should be any at all? It's quite hard to find information about what's normal and what's not.

I think it's amazing it can correct so many and still perform quite well but at the same time, I have the following questions that nobody seems to be able to answer:

1. How can I fix the SNR from home (or can't I?) I read that you check all connections accessible to you, and I have, and they're all good. If it's not them, can it be fixed from the cabinet, or will I need a new cable running?
2. Does everyone have Pre-RS errors? I don't think millions can be norma and like you say, must be having an impact.

Thanks again.
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