Post RS Errors
 

I've noticed for a couple of weeks now that I've been getting some post rs errors showing in the downstream stats. If I've understood correctly, these are packets of data that can't be corrected? Current values are below:

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 5 1 2 3 4 6 7 8
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) -1.37 -1.73 -1.63 -1.39 -1.33 -1.05 -1.05 -1.08
RxMER (dB) 34.63 34.63 34.35 34.63 34.77 34.77 34.77 34.63
Pre RS Errors 100113 94327 120390 106905 61287 80476 82631 121075
Post RS Errors 14220 4505 1530 11368 19479 20452 20391 20630

The SH2 was reset 4 days ago and I cleared the counters after it had finished booting up. Are they anything to be concerned about? Speed and ping seems fine.

Re: Post RS Errors
 

The MER Levels are borderline hence the Pre/Post Errors. So could need investigating

Re: Post RS Errors
 

those levels are fine

Re: Post RS Errors
 

Nobody will investigate an SNR over 34db

Re: Post RS Errors
 

Haven't had any more post rs errors overnight, pre rs have gone up but I don't think they are anything to be concerned about? Any ideas why the post rs errors are occuring? Doesn't seem to be affecting anything as far as I can tell.

Is it possible to adjust the SNR from my side? Or is it something that is done in the cabinet? I know I can adjust the power levels through different value attenuators.

Re: Post RS Errors
 

Do you actually have problems with your internet access? If so, what?

Re: Post RS Errors
 

Not that I've noticed, was just more out of curiosity than anything.

Re: Post RS Errors
 

Sometimes a loose coax connection going into your router causes this.

Re: Post RS Errors
 

Both ends are tight from the internal wall box to the modem. Not checked outside in the external wall box.

Re: Post RS Errors
 

Sometimes thats just the snr of the area

Re: Post RS Errors
 

Over 34dB no, but under 34dB then that will cause problems as was experienced

Re: Post RS Errors
 

Was going to post back and say that everything was fine after reseating the coax cable and resetting the SH on Wednesday. Post RS errors stayed at 0 until Thursday morning. Gone back up into the thousands again now. Did have a brief loss of sync Thursday morning. Can't see anything obviously wrong other than 3 of the channels are a smidge below 34dB.

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 5 1 2 3 4 6 7 8
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) -0.99 -1.52 -1.36 -1.11 -1.06 -0.83 -0.84 -0.78
RxMER (dB) 33.96 34.48 33.60 33.83 34.21 34.21 34.21 34.08
Pre RS Errors 325679 111039 783248 500481 134774 161912 171494 252541
Post RS Errors 16306 11872 16601 16775 16798 16723 16672 16579

Re: Post RS Errors
 

There should be no post-RD errors. They are lost packets and if your downloads are UDP without software checking, the packets are irrecoverable.

It will be down to the SNR (RxMER). I suggest you post on the VM forum so that the VM bods there can check what's happening on your circuit.

Re: Post RS Errors
 

Thanks for the reply Sephiroth. Have posted on the VM forum (as you've already seen). Will have to wait and see what they say.

Re: Post RS Errors
 

Technician came out a bit earlier and couldn't really find anything wrong. Took the 6dB attenuator off as said it wasn't needed. Checked everything was ok with a signal meter.

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 5 1 2 3 4 6 7 8
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 4.50 4.33 4.22 4.47 4.55 4.91 4.82 5.01
RxMER (dB) 34.63 34.63 34.48 34.48 34.63 34.77 34.77 34.63
Pre RS Errors 480 454 625 495 218 114 111 273
Post RS Errors 0 0 0 0 0 0 0 0

SNR has gone up a smidge with the attenuator off. He did suggest it could of just been down to an intermittent issue with SNR dropping briefly? Will keep an eye on it but pretty sure it'll be fine.

Just as an aside and it's something that has been mentioned on here, he did mention that the tiers are likely to be going 100, 200, 300Mb this year.

Re: Post RS Errors
 

Yes - an unnecessary attenuator or splitter does remove components that can break down and cause noise, though your SNR is just about tolerable and not the standard that VM generally want to see, IMO.

Re: Post RS Errors
 

Just been reading your power level and snr sticky thread on the VM forum. If the SNR is above 32dB I'm guessing VM won't do anything? Hence the technician saying everything was ok? Not a great deal I can do I suppose other than monitor it.

Re: Post RS Errors
 

The VM Forum Team usually send an engineer in when it's down at the 33 dBmv mark, which they did. Above 34.5 they'll say it's within tolerance especially if you have no post-RS errors.

Post-RS errors must not happen (except during the first part of modem reset when there is no Sync). VM may respond that 1% is tolerable, but that shouldn't be accepted and must be pushed back.

If VM wanted to move to 1024QAM for higher speeds then 34 would be no good. So they don't want low SNR.

Re: Post RS Errors
 

Seems to be sorted, not had any post RS errors since last Thursday.

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 5 1 2 3 4 6 7 8
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 3.94 3.74 3.72 3.97 4.07 4.31 4.23 4.43
RxMER (dB) 34.48 34.63 34.35 34.35 34.63 34.77 34.77 34.48
Pre RS Errors 132852 115394 182001 150531 65819 34871 41659 84211
Post RS Errors 0 0 0 0 0 0 0 0

Re: Post RS Errors
 

i have the same issue, i had a SNR issue which made my SNR drop to 31dBmv across all channels.

Now its between 37-38dBmv across the board but still Pre RS Errors continue.

Re: Post RS Errors
 

Pre-RS errors are nothing to worry about because the data is corrected in flight.

Re: Post RS Errors
 

Just a note that MER (Modulation Error Ratio) as a measure includes more than just plan SNR (Signal to Noise Ratio).

MER will also reduce for other signal path problems such as amp linearity, filter phase distortions, laser clipping etc.

As Seph indicates this figure is very much borderline. Given the cold weather I wouldn't be surprised if you start to have issues as temperatures rise.

Ian

Re: Post RS Errors
 

As I understand it both MER and SNR take account of all signal issues by the time things arrive at the modem, they're just calculated differently. MER is based on the distance each decoded QAM symbol comes out at from perfect centre of that square in the constellation. SNR is a simpler measure of the power of the noise floor versus the wanted signal.

MER can only be done on digital signals - it is a measure of perfect demodulation versus the actual demodulation.

Re: Post RS Errors
 

Getting post RS errors again.

Downstream
DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 2.81 2.81 2.75 2.94 3.00 3.23 3.26 3.49
RxMER (dB) 32.41 27.97 28.87 29.71 30.95 33.60 34.63 34.63
Pre RS Errors 58368 31994881 16094512 5805880 743797 7286 4690 4686
Post RS Errors 865 1306 931 879 704 753 879 981

The SNR is low on some of the channels, going to guess that something is failing. Weirdly, everything still seems to be working fine for now.

Re: Post RS Errors
 

Looks like a lot of noise on the line. That'll cause low SNR and errors, but it's VM's problem to deal with.

That SNR, especially on the middle channels, is definitely low enough to cause issues in itself.

Re: Post RS Errors
 

Is that something that'll be affecting multiple users? Would VM be able to see/monitor it and pass it on to the network engineers?

Re: Post RS Errors
 

Give them a ring and find out.

Re: Post RS Errors
 

Could do. It all depends on the source of the noise. Could be a dodgy amp, could be something the neighbours plugged in that they shouldn't have, could be a dangling wire somewhere.

Re: Post RS Errors
 

Thanks Kushan and qasdfdsaq. I've bumped the thread I had going on the VM forum. Have to wait and see what they say.

Re: Post RS Errors
 

You would be much better off calling them, they can check for issues there and then, as well as book an engineer if need be.

Re: Post RS Errors
 

Good luck with that if you get the script monkeys!

Re: Post RS Errors
 

Which is exactly why I haven't :p:

Re: Post RS Errors
 

Which is why your issue is still ongoing. Even the "script monkeys" are (usually) capable of checking the outage page and booking a tech. There's a reasonable chance that it would have been fixed by now had you just called in a couple of days ago.

Re: Post RS Errors
 

Go on. Do it and let us know how the conversation ran! It's a percentage game. Good luck!

Re: Post RS Errors
 

Ha, I would but the support team have replied back on the forums to book an engineer. In less than 24 hours as well.

Re: Post RS Errors
 

Ha ha - Kush!

Re: Post RS Errors
 

Noticed a novel thing with the recording of errors by the SH2ac. Once it gets to 200000000, it goes in to negative numbers and counts upwards.

Downstream
DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 4.32 4.10 4.09 4.35 4.37 4.59 4.52 4.68
RxMER (dB) 32.50 28.00 28.94 29.81 31.07 33.72 34.63 34.63
Pre RS Errors 5140313 -1494310897 1385274806 528430914 69359201 255807 51686 55772
Post RS Errors 7827 15968 9034 8199 9790 10211 12189 13226

Re: Post RS Errors
 

That's professional software development for you. Influenced by someone who said "Nah there will never be so many RS errors. The phenomenon you've seen is an effect known as "overflow" leading to the "negative complement"; at least the code was written so that the SH didn't crash.

Your SNR is appalling.

Re: Post RS Errors
 

200,000,000 is a weird number to overflow at. Could it perhaps have been 2,000,000,000 (actually 2,147,483,647)?

[Edit]
Probably was 32-bit signed int overflow. I can see a reading of 1,385,274,806 in there which is over 200,000,000 already. He probably missed out a '0'. 2 billion errors is a lot to have on one channel, but considering routers these days are rated in mpps (million packets per second) it wouldn't take that long at full pelt.

Re: Post RS Errors
 

Oops yeah sorry missed off a 0. Seem to be getting around 100,000 errors after every refresh (think it refreshes around every 5 seconds if you keep hitting the refresh button)

Re: Post RS Errors
 

I don't see why that's amusing, the point still stands - phoning in, even to offshore, is 9 times out of 10 the fastest way to get an issue resolved. The forum support team is good, but it still takes time and if everyone went via the forum, it'd take days to spot local issues rather than hours.

As inept as some offshore agents are, even the worst are capable of booking a tec and had OP just phoned in, he'd have likely had a tech the next day. Now this has gone on for several days.

My first thought as well. A surprisingly common occurrence, these days. Then again, I can understand why the developer never gave much thought to the data type, a signed 32bit integer should be enough for anyone :P

Re: Post RS Errors
 

Understand what your saying Kushan, only reason I haven't is that it doesn't seem to be causing a noticeable effect on the connection. I still get full speed and the ping monitor looks ok:

https://www.cableforum.co.uk/images/...2015/04/31.png

I'm quite happy to wait for an engineer. Having said all that, I've just had another look at the downstream stats and the SNR has gone back to what it was. I've no idea whether I actually need an engineer now or not?

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 3.14 3.16 3.10 3.32 3.36 3.47 3.49 3.73
RxMER (dB) 34.48 34.35 34.35 34.48 34.63 34.63 34.35 34.35
Pre RS Errors 14472186 1700150773 -1460133266 1116306445 164902362 2184339 1003479 1397140
Post RS Errors 28762 2164659 222446 25030 39024 44539 51789 55981

Re: Post RS Errors
 

It all depends on the Post-RS errors and whether or not they are rising. With those SNR levels, it should not be rising much if at all, but the Pre-RS count would be rising significantly; they don't matter if Post-RS is not rising.

It's power level and SNR stability that's required here and an engineer is required as first step if there is no stability. Not that he can do much other than check all the physical bits and your cabinet tap. Then he can escalate to Networks.

Re: Post RS Errors
 

The Post RS errors are still going up even though the SNR hasn't changed from the last post. Engineer is booked for Thursday, no idea what (s)he'll be able to do, probably say everything is fine :p:

Re: Post RS Errors
 

Probably pretend the hub is faulty

Re: Post RS Errors
 

JB might care to comment, but AFAIK the Techs are being briefed that 34 dB is the low acceptable SNR. So yes - expect what you said!

Re: Post RS Errors
 

In my area if it's below 34 I pass it to networks for them to check as they don't supply us with a meter that can measure it. If it's above 34db networks won't attend

Re: Post RS Errors
 

So, basically it's going to be a waste of time unless the SNR happens to drop again by Thursday. The bloke who came last time did have a meter and he couldn't find anything wrong. If the SNR was just that bit higher, I probably wouldn't be getting the errors. Presumably only the network engineers can adjust it?

Re: Post RS Errors
 

Depends whats causing it, if I had a meter, Id measure it at the cab, if its good there but poor at the end of the drop you know where the fault lies,

Actually, do you have a fault or is it that you are looking at the stats?

Re: Post RS Errors
 

Not as such no, the SNR did drop to around 28dB on some of the downstream channels from Thursday of last week until Monday when it went back up. That's when I updated the thread on the VM forum and they agreed to book an engineer. The booking wasn't done until yesterday. Had a few PM's from the support person that was looking into it, they couldn't find any evidence of any work being done by networks for the SNR to recover on Monday. They wanted to book an engineer just to make sure that I wasn't going to be having the same "issue" again in a few weeks. The Post-RS errors are still going up, seem to come in bursts, I believe that's the "fault" but whats causing it I don't know.

Re: Post RS Errors
 

I see, well I think it will probably be a waste of time again, let us know if the tech did anything,

Re: Post RS Errors
 

Tech has been and gone, unsurprisingly couldn't find anything wrong. He did ring up his team (network engineers?) and they couldn't find anything wrong. What they could see matched what was being reported, said Cardi(?) was at 0%. Re-booted the SH. So looks as though I'll just have to leave it unless things do start causing issues.

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 2.67 2.68 2.63 2.84 2.86 2.99 3.03 3.28
RxMER (dB) 34.63 34.63 34.63 34.63 34.77 34.77 34.63 34.48
Pre RS Errors 388 423 452 382 326 334 353 1120
Post RS Errors 0 0 0 0 0 0 0 0

Re: Post RS Errors
 

All your stats look spot on right now. CARDIE (AFAIK that's how it's spelled, cannot remember what it stands for) is the tool they use to gauge noise on your cable. 0% is a good thing generally, but that can be measured over different periods. 0% over the last hour doesn't mean much, 0% over 24hours is better.

The way the cable tech works, is there's expected to be a certain level of error - it happens, even on a good day. Sometimes you can correct that error (known as FEC - Forward Error Correction), sometimes you can't (FEC Errors) and the data has to be retransmitted - again, this is normal and will happen on occasion on even good lines. The more FEC Errors, the higher the score gets.

Likewise, the lines can automatically drop down to different modulations that are less affected by noise. QAM64 might drop to QAM16, for example, which has a lot less bandwidth but some bandwidth is better than none at all (This is why "slow speeds" doesn't always mean congestion, it could mean there's noise on the line killing the modulation, so everyone has less bandwidth to share). If that happens, the score goes up. If it hits QPSK, it's even worse.

I've seen CARDIE scores of 70%+ and that generally means everything's ****ed. If I recall correctly, anything above 30% over a 24 hour period needs to be raised to networks.

Oddly enough, when the entire line is down, CARDIE seems to report exactly 25%. I have no idea why.

Re: Post RS Errors
 

Suprise surprise this happening again. Did have an issue with packet loss yesterday:

http://www.thinkbroadband.com/ping/s...08-04-2015.png

Since then this has been the levels.

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 0.94 0.72 0.63 0.89 1.04 1.30 1.22 1.45
RxMER (dB) 33.96 33.60 33.38 33.72 34.08 32.68 34.21 34.08
Pre RS Errors 145006 118227 213398 181654 76841 5237769 59250 61414
Post RS Errors 21882 11116 18543 19737 20772 82784 23303 23847

Upstream
US-1 US-2 US-3 US-4
Channel Type 2.0 N/A N/A 2.0
Channel ID 50 N/A N/A 49
Frequency (Hz) 39400000 N/A N/A 46200000
Ranging Status Success N/A N/A Success
Modulation 16QAM N/A N/A 16QAM
Symbol Rate (Sym/sec) 5120000 N/A N/A 5120000
Mini-Slot Size 4 N/A N/A 4
Power Level (dBmV) 55.00 N/A N/A 55.21
T1 Timeouts 0 0 0 0
T2 Timeouts 0 0 0 0
T3 Timeouts 2 0 0 0
T4 Timeouts 0 0 0 0

Trying to get the people on the phone to book a tech is a nightmare. As far as their concerned, if your getting full speed, which I am, there's nothing wrong. Might have to go via retentions. Last resort would be the forum but it's bound to change before they respond and get a tech out.

Re: Post RS Errors
 

You will get a tech no problem with an upstream above 51

Re: Post RS Errors
 

Downstream SNR is also poor as you've noticed. What about the neighbours? Anything bad going on there?

Re: Post RS Errors
 

Immediate neighbours seem to be on Sky or a BT product as far as I can tell.

Re: Post RS Errors
 

Any neighbours! Reason I ask (not being at your house) is that either the problem is down to your specific connection, or the amplifier or an active component along the cascade is misbehaving.

Typical causes of your specific connection being bad might be:

- Water in your street tap point;
- Loose coax connections inside the house or in the outside Omnibox;
- Duff passive components at the street cabinet at your tap point;
- Duff Superhub

Re: Post RS Errors
 

I've checked that the coax connections both inside and out are tight. They seem to be but doesn't mean there isn't anything wrong. I did wonder if it could be a duff Superhub, seems to have happened since getting the 2ac but it could just be coincidence. Plus the fact you can't see the pre or post RS errors on the Superhub 1 (as far as I'm aware). Other 2 I've no idea. Thing is neither of the 2 techs have actually physically checked anything. Just checked that the levels are ok, 1 with a meter, the other with a PDA. Typically both times they were, seems to be intermittent which I appreciate are always difficult to track down.

Re: Post RS Errors
 

This is why Techs need better tools. I need a meter to plug into the taps and see that what the SNR is, if its poor pass to networks if not move to end of the drop, if poor book a repull if not move on.....

Same with upstream

Re: Post RS Errors
 

Newer cable modems are basically full-capture spectrum analysers. They may issue those or, alternatively, as more of those arrive on the network they can just query them remotely for network conditions.

Re: Post RS Errors
 

The problem with that is you need someone clever enough on the end of the phone to look at it rather than "book a tech" for a "closer look" with no diagnostic tools to scratch his head and swap out the hub again.

Re: Post RS Errors
 

Nah, just a decent front end that colours the numbers in lots of green / red / amber along with a workflow that shoves it in the agent's face before they're allowed to book a tech ;)

Re: Post RS Errors
 

I agree JB, upstream meters should be a necessity.

Re: Post RS Errors
 

I don't understand, Virgin already has this. It's called Red Tools. It shows all the modem stats, as well as a bunch of other stuff. It also lets you remotely reboot the hub and works for STBs as well.

Agents are trained on power levels and what to look for, acceptable SNR and that sort of thing. They have tools for monitoring all of the statistics, BADGER for utilisation, Cardie for noise and all first line agents are trained to use them. Failing that, second line can log straight into the UBR.

Re: Post RS Errors
 

What are you hoping for an upstream meter to tell you?

Re: Post RS Errors
 

The most common BB fault when I was a service tech was high upstream. To have a meter to give you a reading of what that was at a given point saves masses amounts of time.

Re: Post RS Errors
 

One example is I can go to a house and the upstream is 49db and I think that's fine no fault there. But after I get a repeat fault my principal tech who has an upstream meter finds out the upstream at the taps is 34db. So I've lost over 10db on the drop so there must be a heatshrink or damage to it. I have no tools to check that

Re: Post RS Errors
 

Re: Post RS Errors
 

In the example the 10db loss was over the drop (tested at the omni), there was a damaged join under the lawn that caused the stinger to go rusty causing low frequecies to be blocked but allowed higher frequencies through. With correct tools it would have been a doddle to diagnose

Re: Post RS Errors
 

Right tech has been, was the same person as last time. He could immediately see there was a problem as his PDA was showing a fail on the upstream test. He could also see that the downstream SNR was low. Went off to the cabinet and adjusted the upstream there. So thats been lowered but he still wasn't happy with the downstream SNR. Rang up the same people who gave the CARDIE reading before and they said it was fine. I don't think he was convinced, so he rang networks and passed it on to them. They are going to monitor it over the next few days and the tech is going to call me back on Thursday. Stats are currently:

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 8.90 8.88 8.79 8.91 8.93 9.44 9.60 9.87
RxMER (dB) 33.72 33.72 33.60 33.60 33.96 34.08 33.83 34.08
Pre RS Errors 863274 9317351 11353577 5384277 1393045 13566411 429405 510327
Post RS Errors 128220 80392 107277 114269 164189 251900 183539 183389

Upstream
US-1 US-2 US-3 US-4
Channel Type 2.0 N/A N/A 2.0
Channel ID 50 N/A N/A 49
Frequency (Hz) 39400000 N/A N/A 46200000
Ranging Status Success N/A N/A Success
Modulation 16QAM N/A N/A 16QAM
Symbol Rate (Sym/sec) 5120000 N/A N/A 5120000
Mini-Slot Size 4 N/A N/A 4
Power Level (dBmV) 49.00 N/A N/A 48.96
T1 Timeouts 0 0 0 0
T2 Timeouts 0 0 0 0
T3 Timeouts 2 0 0 5
T4 Timeouts 0 0 0 0

Hopefully networks find something but I'm not overly convinced they'll sort it.

Does the fact that one of the upstream values ending in .x6 mean anything? I thought that the value incremented in .25 steps. I wonder if it's worth asking the lady I'm dealing with on the VM forum to perhaps send out another Superhub, just to rule it out.

Re: Post RS Errors
 

Had a call back from the tech (voicemail) and networks have told him there is a fault affecting the area but it's at the headend. It's being worked on at the moment. Think he's going to call back later, may have some more info.

Re: Post RS Errors
 

Figures: You've got a large increase in DS signal strength but no improvement in RxMER so the problem is upstream of you. Once it's all fixed up a FPA of about 6db would get everything in the right bounds.

Re: Post RS Errors
 

That's right. The high power amplified the noise!

Re: Post RS Errors
 

Any idea what they might be doing to fix it?

Re: Post RS Errors
 

Is the only way VM change the power still by physical tap change and attenuators? Mine so good for the last couple of years after new kit fitted in the street cab I assumed they were able to actively control downstream at 0dB?

SHUB1 so no rs errors

Hope they can do same to yours Jon22

Re: Post RS Errors
 

I've got some FPA's somewhere, not sure if I have a 6dB though. So, I'll stick one of those on once everything is sorted.

Re: Post RS Errors
 

They should have seen it and be trying to find the source. What's going on in your VM Forum thread on this?

Re: Post RS Errors
 

I've resorted to PMing one of the team, seem to get a faster response that way. The person couldn't see that any fault reference had been raised though but did say it could of been a bit too early for it.

Upstream power level has dropped overnight, downstream SNR is still low.

Upstream
US-1 US-2 US-3 US-4
Channel Type 2.0 N/A N/A 2.0
Channel ID 50 N/A N/A 49
Frequency (Hz) 39400000 N/A N/A 46200000
Ranging Status Success N/A N/A Success
Modulation 16QAM N/A N/A 16QAM
Symbol Rate (Sym/sec) 5120000 N/A N/A 5120000
Mini-Slot Size 4 N/A N/A 4
Power Level (dBmV) 43.75 N/A N/A 43.96
T1 Timeouts 0 0 0 0
T2 Timeouts 0 0 0 0
T3 Timeouts 2 0 0 5
T4 Timeouts 0 0 0 0

Downstream
DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 8.29 7.92 7.78 7.92 8.15 8.81 8.88 9.07
RxMER (dB) 33.38 33.16 33.16 33.16 33.60 33.72 33.72 33.72
Pre RS Errors 1220703 9651255 11868496 5900224 1630301 13744573 621134 704209
Post RS Errors 140510 82871 109604 117715

Just had another call from the tech, he reckoned it should be sorted within the next week or so.

Re: Post RS Errors
 

For individual customers, yes.

It can only be controlled on a per-channel-per-node basis. Changing it would affect every customer connected to that shared channel, which could be thousands.

---------- Post added at 12:04 ---------- Previous post was at 12:03 ----------

Given the location of the problem is upstream from his cab, it probably needs second level (Networks?) to look at it. Ordinary techs can't deal with stuff that far up AFAIK.

Re: Post RS Errors
 

Yeah that's what the tech told me yesterday. He deals with problems from the house to the cab, anything else is passed on to networks.

Re: Post RS Errors
 

Looks as though some work has been done this afternoon.

DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 11.25 10.61 10.50 10.78 11.08 11.65 11.68 11.85
RxMER (dB) 35.97 35.78 35.42 35.78 36.17 36.17 36.17 36.17
Pre RS Errors 1364411 9842024 12172551 6105944 1787834 13892642 777371 867447
Post RS Errors 190192 106279 134757 148091 245359 343382 278423 282756

Re: Post RS Errors
 

not really, it has got worse. You downstream power has gone up and it needs to go way down.

Re: Post RS Errors
 

Well at least the SNR has improved... :p:

Re: Post RS Errors
 

Well the RxMER picked up a bit but the DS power's getting too high. If the OP's got some FPA's now's the time deploy some before he looses connectivity.

Re: Post RS Errors
 

At least this time it's gone up without a concomitant increase in noise.

I suppose that's one way to find the source of the noise, if you're lazy. Turn the power up at each accessible point on the line to see which change increases power without increasing noise.

Re: Post RS Errors
 

10 dB be ok? I've got a 6dB coming if not. Although I don't know if there's any more work being done.

Re: Post RS Errors
 

Either would be fine. Just keep an eye on the levels and adjust accordingly.

Re: Post RS Errors
 

10db should do a treat but as they're obviously still mucking about keep an eye on the levels. Once they identify the noisy node the levels could fluctuate as they apply the fix. Whatever that might be.:erm:

Re: Post RS Errors
 

It could be a box swap? But based on your previous reply to me DS power will have gone up for lots of others too - so I doubt they are finished yet!

Re: Post RS Errors
 

I've put the 10dB attenuator on, it's lowered the downstream power levels to between 1 and 2 dBmV. Be interesting to see if anything else going to be done.

Re: Post RS Errors
 

So it's been a week since whatever was done to bring the SNR up a bit yet I'm still getting the Post RS errors. Not as many as before though.


Downstream
DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 0.95 0.35 0.49 0.74 0.81 1.18 1.20 1.24
RxMER (dB) 36.61 36.61 36.39 36.39 36.84 36.84 36.84 36.84
Pre RS Errors 34372 32607 40905 28075 29114 27782 28638 28708
Post RS Errors 15235 5064 15724 11469 15712 16117 17230 17388

Re: Post RS Errors
 

The power levels and snr are excellent, reset the rs errors counter and see what happens.

Re: Post RS Errors
 

I reset them yesterday. Seem to get a burst of them after a few hours.

Re: Post RS Errors
 

Has the modem reset at all during that period? Or have you rebooted it?

Re: Post RS Errors
 

Last time I rebooted the modem was after I put the attenuator on. There's been 1 T3 timeout since.

Re: Post RS Errors
 

So the post RS errors were cleared after the reset and no reset has occurred since?

Re: Post RS Errors
 

Yep, reset the counters after and also reset them yesterday. Haven't rebooted the modem since last week. Gone up a bit more since the last stat post.

Downstream
DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 267000000 275000000 283000000 291000000 307000000 315000000 323000000
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Locked Locked
Channel ID 13 9 10 11 12 14 15 16
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17
Power Level (dBmV) 1.98 1.53 1.49 1.61 1.66 2.29 2.51 2.47
RxMER (dB) 36.61 36.61 36.39 36.39 36.84 36.84 36.84 36.84
Pre RS Errors 42452 42428 49518 35967 36538 35003 36033 35696
Post RS Errors 17977 7663 18163 14121 18401 19061 20287 20107

Re: Post RS Errors
 

Mmm.

If these are causing a service problem and the same thing isn't being seen with the rest of the people on your tap I reckon you could do with being moved to another port in the cabinet.

If that doesn't sort it might need a repull - new cable between you and cabinet.

Re: Post RS Errors
 

Been sending more PM's back and to, to the person I'm dealing with on the VM forum. Looks as though they are going to arrange for another Superhub to be sent out. Don't know if it'll help but would at least rule it out. If not, I'll have to somehow see if they can arrange to do what Ignitionnet has suggested. Not quite sure how I'm going to approach that.