50M : Post RS Errors

[Sephiroth]

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!

[jb66]

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

[Jon22]

Originally Posted by jb66

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

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?

[jb66]

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?

[Jon22]

Originally Posted by jb66

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?

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.

[jb66]

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

[Jon22]

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

[Kushan]

Originally Posted by Jon22

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

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.

[Jon22]

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



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.

[jb66]

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

[Sephiroth]

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

[Jon22]

Originally Posted by Sephiroth

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

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

[Sephiroth]

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

[Jon22]

Originally Posted by Sephiroth

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

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.

[jb66]

Originally Posted by Jon22

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.

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