Question for an Openreach engineer

Evening folks,

Wondering if any Openreach engineers out there might explain something to me. Pure curiousity.

Had a visit the other day from Openreach to look at my line's instability. I was chattering away with the chap, and I mentioned Hawk. Apparently Hawk's no longer used. There's a new bit of kit which seems to be able to perform a multitude of tests instead. Anyway, during the test, he said my line quality is excellent with a value of seventy-something, and in the same breath said that anything over fifty is good. So I'm wondering what this value is? I know one thing it won't be is line attenuation in db!

Cheers for any forthcoming explanation of the mystery value.

Kev.

Noise margin? Although against what? Which frequencies?

Edited by Andrue (Tue 17-Mar-09 08:30:47)

That's the $64000 question Andrue. If there's any correlation, my router stats are something like: -

D/S synch 1824kbps
D/S noise margin 6db
D/S attenuation 63db (possibly higher, but that's all the router will report)
U/S synch 448kbps
U/S noise margin 11db (from memory, I don't pay much attention to it)
U/S attenuation 31db (ditto above)

Kev.

I believe it may be just a dimensionless number - which is the overall quality of the line which take into account, attenuation (up and down), the difference in attenuation, SNRs, various frequency test results, leg capacitive balance, and several other factors. Each factors adds a little to the score - or take some away from a maximum value.

That sounds like a possibility. Perhaps a score out of 100 based on all the line's qualities. I really should've asked the engineer while I was there.

In reply to a post by dicko1975:

...Had a visit the other day from Openreach to look at my line's instability...

It's all very well Openreach saying you've got a good line but did he manage to correct your stability problems?

If yours is good with 63dB attenuation I fail to see how the magic number whatever it is relates to ADSL - it must be some voice only measure.

Er, no. As usual, whenever Openreach visit, the line performs flawlessly. I've ordered myself a filtered face plate from ADSLNation, so as soon as I've got that fitted I'll monitor the connection for another week or two before logging another fault. Before he left, he did say he'd leave a note on the report to the effect that if the problem persists, a "lift and shift" may be required. Gonna have to wait and see!

Exactly. As the crow flies, I'm almost 4km from the exchange, hence the 63db attenuation. I consider myself pretty lucky in that I can achieve a synch of almost 2000kbps with a tail wind, so maybe it refers to some other "quality" of the line. For what it's worth, I've always considered our phone line to be very quiet on the voice side.

I'm trying to remember how he performed this particular test. I'm not sure whether it was the one where he had to grab his mobile and dial up the automated test system.

Hmmm - so much for BT's test

I can recommend RouterStats if you haven't already heard of it to monitor your connection.

In reply to a post by kwikbreaks:

If yours is good with 63dB attenuation I fail to see how the magic number whatever it is relates to ADSL - it must be some voice only measure.

Unless it's relative. IOW "for a line with 63db attenuation it scores 70 out of 100". Unlikely though. "Your dog runs very quickly considering it's only got one leg and has been dead for a month"

In reply to a post by dicko1975:

For what it's worth, I've always considered our phone line to be very quiet on the voice side.

If you can find an someone that knows about it, the audio gain can be adjusted. I had this done last year to help with a quiet and not-very-good line, but it took a second engineer to tell the newer guy it was possible.

The engineer was referring to the AC/Longitudinal balance of the line, it measures the lines susceptibility to noise ingress etc.

Thanks zhevkov. So does that mean the higher the number, the less susceptible the line is to noise?