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Moving from band to band?

grahamt
Rising Star
Posts: 565
Thanks: 13
Registered: ‎05-04-2008

Moving from band to band?

Here's something that may shed more light on the way banded profiles work.
I'd previously thought that lines moved from being banded to being free. But my recent experience suggests that lines that have been banded for a long time can be moved from one band to another when line conditions change.
In mid-November I had the bell wire removed from my line(s) (it's a slightly complicated, star-wired setup). At the time I'd been in the 1472-3072 band for over a month, generally syncing at a bit below the max, usually at 3069. After the change my noise margin immediately improved, as I expected.
On 30th November I started syncing at 4538. That's just below the max of the 2272-4544 band. This stayed the same (and the line was very well-behaved, staying up for several days between resyncs) until last Friday, when I started to sync at 6653. That's just below the max of the 3328-6656 band.
So I think I'm probably still banded, but because my line conditions have improved I'm gradually moving up the bands. I don't know if I'll ever move to a higher band than I'm on now, because my sync speed looks about right for an attenuation of 38dB. Maybe it could go a little bit higher, but it might not. In some ways I now hope my line isn't completely freed up, because that might mean it would be set too fast and then rebanded at a lower band.
Sadly, I can't (yet?) take full advantage of this improved sync speed. On Saturday morning both my Plusnet and BT profiles were still at 3500. In the evening I saw that my Plusnet profile was 5500 (which it still is at the time of writing). I did a speed test, but it was still giving me a throughput of about 3200, so I thought that my BT profile could be at 3500. I couldn't test this because I couldn't get the BT speedtester to start. This morning, however, it worked and confirmed that my BT profile is 3500.  Strangely, the test showed my throughput as 3601! I've never seen throughput faster than the profile before.
Can the Plusnet profile ever change before the BT profile? I thought it always follows BT changes, which means that my BT profile must have gone up to 5500 sometime on Saturday and then for some reason fallen back. But I'm still syncing at 6653. Odd. I'll wait to see whether there's change in the next 24 hours.
Graham
4 REPLIES
Mand
Grafter
Posts: 5,560
Thanks: 1
Registered: ‎05-04-2007

Re: Moving from band to band?

You shouldn't be able to get throughput faster than your profile. Very strange indeed.
What's your profile at now?
grahamt
Rising Star
Posts: 565
Thanks: 13
Registered: ‎05-04-2008

Re: Moving from band to band?

By early on Monday morning (00:45) my BT profile had (I assume) caught up with my Plusnet profile (5500) and ever since then I've been getting throughput of about 5mb/s on the standard Plusnet/MyBroadband speedtest. Still syncing at 6653/816, with SNR around 12 in daylight, dropping to 6-8 after dark.
After a long time of having a throughput of around 2.2mb/s, I'm very happy. It shows what a difference disconnecting the bell wire can make on a slightly complicated wiring system.
Graham
32110
Grafter
Posts: 147
Registered: ‎30-04-2009

Re: Moving from band to band?

Mand - I frequently get download test speed results on BT speed tester that are greater than my BT/PN profiles. Currently, and for a little while now, both BT and PN profiles are registering 9000 but as you can see from attached speed test, download is reported well over 9000. Huh
grahamt
Rising Star
Posts: 565
Thanks: 13
Registered: ‎05-04-2008

Re: Moving from band to band?

I think the most obvious explanation is that the download throughput reported by te BT speedtester is often wrong. Usually when it's wrong it reports a much slower throughput than other speedtesters, but I guess it's possible that it sometimes gets things wrong in the other direction.
Graham