Loss of Signal / HEC errors

AntiRip

hi all

Every evening at about 8pm and this evening even earlier I get billions of HEC errors on my line. My profile then reduces from 4096 to to 2700/2800 download.

Even if I reset/restart my router the HEC errors will reset but the profile will stay the same. I have to reset my router every morning to get my 4096 speeds back.

Now my line inside the house. The phone line comes into the attic where it goes into a small box with fuses inside. The two wires comes out (red and blue) down to the socket. I put a microfilter on this to split the cable into two separate lines, one for a digital phone and one for the router. No sky box. Is this right?


Any help apprciated
Thanks

lucernarian

If those stats are right, the phone line looks a little noisy or else there's some interference etc. The attenuation values should definitely allow at least 3mb download speeds. The signal margin is accordingly too low. If it's associated with a time then some sort of external interference is causing it. Anything from a dodgy street light or fluorescent light inside to a heating thermostat or some sort of timer kicking in.

In other words, it could be a real pain in the backside to fix. Some things that might help include disconnecting any unnecessary phone line extensions, using a special master socket with a built-in filter to separate off all extension sockets and ensuring that the phone wires inside the house are using proper cables and not flat telephone lead or mains flex etc.

AntiRip

Just a quick question to see if this is the cause. There are only two wires coming down from the attic (from a fuse box) and these are the phone wires that go into the phone. The shielding is then paired off and two other wires attached to go to the router. 30 year old job I'm afraid. No such thing as master socket here. I wonder if this is the cause could I get an engineer to repair?

lucernarian

It'll cost you. I'm not sure how much. The line is working at a slower speed but still functional. If you claim it disconnects every few minutes they may simply lower your speed to 1 meg and then if it stops the problem is "fixed".

Phone wires aren't fused as such. Some old phone lines in older houses may have a glass fuse for lightning strikes. They certainly shouldn't be in a mains fuse box, under wiring regulations phone wires and mains electricity wires are not supposed to share the same cabinet or conduit I believe.

Most electricians aren't particularly knowledgeable on phone wiring either and will use any auld wire and simply join the right colour wires and assume that's that. Here's the document that gives the overview of how house telephone wiring should be done: http://www.reci.ie/Portals/0/RECIDocuments/technicalinfo/eircominterface.pdf

AntiRip

Well, I put all new wiring in and got rid of any junction box (splitter boxes). Working extremely well since. I have reduced the Line Attenuation from 21.5(up)/41.0(down) to 19.5(up)/39.0(down) and the noise margin was 12.0(up)/8.0(down) is now 12.0(up)/17.5(down).

The down SN margin reduces to 10-11dB in the evening.

Do you think with these settings I can go up a profile? I'm currently on the up to 8mb package but on a 4mb profile because of my bad line before I improved it.

Thanks

lucernarian

The signal margin readings of a line only give the snapshot in time of how well the line is performing. You'd want to check it a few times over the course of the evening or whenever the signal margin tends to be lowest. Maybe 10 times at different points in the evening. If it has a habit of dropping below 9-10dB, I'd give the 5 mbps profile upgrade a miss.

AntiRip

Thanks To_be_confirmed. It's at 16dB now. Between now and 8.30p.m is usually the lowest although with the brighter evenings it may be pushed out later now.

Sorry to bother you but do you know is there a set amount of dB's the line drops for each profile? I have seen on other sites that ISP's take 6dB as the lowest a stable line should maintain

lucernarian

The 6dB signal margin is a rule of thumb. Some lines may have a signal margin that only fluctuates a couple of dBs over a day. Others can have drops of 8 or 10 dB even. I have noticed a trend for urban areas to suffer more significant drops, unfortunately for you. 6dB is a good rule of thumb but you could take a chance on it and if it doesn't work out, ask for it to be dropped back to the existing speed.

AntiRip

To_be_confirmed wrote: »

The 6dB signal margin is a rule of thumb. Some lines may have a signal margin that only fluctuates a couple of dBs over a day. Others can have drops of 8 or 10 dB even. I have noticed a trend for urban areas to suffer more significant drops, unfortunately for you. 6dB is a good rule of thumb but you could take a chance on it and if it doesn't work out, ask for it to be dropped back to the existing speed.

Well, it didn't drop below 13.5dB last night so contacted support today. They seem to think my line can take 7mb now. I told them I'll try 5mb first and see how it goes

My SN Margin has dropped from 17dB to 13dB now

darth_maul

sounds like a fauty street light causing interference,

~ Noise Spikes
A lot of low SNR problems may be related to noise spikes where "noise" comes from an outside source or electrical interference. You may be able to monitor your SNR Margin and identify a pattern which correlates to your low SNR. Common causes may be microwaves, central heating pumps, street lighting, xmas lights, treadmills, the list is practically endless.
Some users have reported success in tracking down the source of the noise using a portable AM radio. The radio should be tuned in between stations somewhere in the region of 612 Khz until you hear static noise.

Read more: http://www.kitz.co.uk/adsl/lowSNR.htm#ixzz1IIeyVCSL