BT Business Hub (2700HGV) and long phone lines

[#1]

Thanks Grudkin, I have been looking to get one off Ebay, but no luck so far.
In the meantime, I've applied to Plusnet to have my target SNRM reduced from 12 to 9, then I can reevaluate the 2700HGV. The lowest SNRM I've been able to hang on to is one that stays at around 6-6.25 thru the day, and drops to 5'ish in the evening, so 9 ought to be fine.

[#2]

Don't know if this is allowed in these forums but i'm willing to help you out as i have 2 ( 1 being surplus to requirement), being a long liner too we should stick together hehehe , i can do it all legal via fleabay if you wish PM me and we will chat . its an ex  sky branded one but the same as an generic one .

[#3]

Final update on the 2700HGV ;
I've now tried it on a more level playing field with the SNRM-adjustable routers - I've had my target SNRM dropped by Plusnet to 9. At this level, the HGV does not achieve  as high a sync rate as the best of the rest, but maintains its performance in a smoother way than many. Its in-use SNRM doesn't fluctuate as much as many of the others - on routerstats its almost completely a smooth line, with just a few small dips between 22:00 and 05:00.
It also has something I've not encountered on the other DMT-monitorable routers I've tried - dynamic control of the marking/unmarking of 'tones' found to be unusable. Other routers seem to need a resync/reboot in order to free-up tones once they're noted as being unusable. This feature should enable the HGV to be left running for long periods without resyncs etc.
Its now back into my top 3 for my long-line, high attenuation line, together with the DG834G V4 and the ST585 V6

[#4]

Hi
The 2700HGv may seem a more smooth line because it's SNRM is only displayed in whole numbers.
All other routers i have encountered display to one decimal place.
Saying that it is a very good router on long noisey lines.
Ian

[#5]

It might be worth mentioning that noise levels (day time especially) seem to have been getting quieter the last week/10 days or so. A bit like a mill pond compared to a couple of weeks ago at the moment and not as low, doesn't drop as low at night either, but still the same day - night range interestingly.
It might be worth doing a few more tests.
Don't forget the tip when swapping, to powerdown the modem/router and wait a while before disconnecting the line.

[#6]

Can you tell me why one should wait a while before disconnecting the line after powering down the router?  How long is a "while" in this context ( a few seconds, a few minutes....)?

[#7]

The longer the better, depends what you want to do, how many errors you are getting on your line, how marginal it is...... If you just unplug the line and do it one to many times in a short space of time, the DLM thinks you have a problem with the line and will raise the target SNRM to try and stabilise the line. I normally recommend no more than 5 disconnects within an hour and then leave it alone for the rest of the day. You may get away with more, on the otherhand with marginal conditions a couple of disconnects might do it.

[#8]

I am trying to diagnoze a sync rate problem so there is a degree of connecting and disconnecting things.  However I think my SNR margin is now at its maximum value so I hope it can't get any worse!  I am not sure what error rate is acceptable and I don't really understand how to get this information from my router.  It's not available from the web interface and I haven't got to grips with the CLI.

[#9]

Ah, right regarding stats, but even if the target has gone to 15dB persistent disconnects will mean it will take a lot longer to recover. If we can keep future posts the the other thread (otherwise it will get far too confusing) post you router detail in that thread (noting my suggestions) and we'll try and take it forward from there.

[#10]

Quote

zyxel  P-660HW-T1  Because it seems to operate at SNRM 6, I'm beginning to wonder if the modem is set to operate at a pre-defined offset.

can confirm that the post office supplied zyxel P-660HW-T1 v3 ive got on this 63+db line syncs with a fixed 6db NM, where my dg834 v4 syncs to what the DLM says is right NM and even with a snr tweak right down to 6db and beyound on the dg834 v4 it still syncs a good 250-500kbps less than the zyxel and finds it very hard to hold on to the sync.