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[nickdanby]

I think that this is a great site for information about broadband matters and ADSL, so I
would like to add a bit of information concerning the ability of certain modem/routers
to get a good synchronisation speed. I am a volunteer with a rural radio broadband
organisation and have access to various kit.

I personally have a normal ADSL line over 6Km from the exchange which syncs between
3200 and 3550 kbps. It has never been higher than 3520 in the 3 years that I have had
the line. These figures are the same with a number of modem/routers (BT Voyager 2110,
Billion 7402 and 7402R2, Safecom SAMR-4114 and SART2-4115, Netgear DG834GV4 and another
one simply marked ADSL2-2_ModemRouter) and none of these varied very much when
connecting. Also if they managed to connect at the higher speed of over 3424 kbps
(putting me on a 3Mbps profile after 3 days) they would eventually drop out when the
line became poor and the noise margin dropped below about 3dB. Most of these devices
were used for a week or more, so I am not talking about one off measurements.
Incidently I normally use the BT Voyager because I thought the stats were best.

However I was asked to check a couple of BT Homehubs (BT2700HG-B and BT1800HG) both
made by 2Wire. Both of these synchronised at over 3750! I tried this a few times and
each time was the same. I have never had such high syncs speeds. I therefore purchased
a (BT2700HG-V) and have set it up as my normal device. It has always connected at 3744
and over. Also the noise margin does drop on occasions to about 2dB but it has never
re-synched. So I am now on a stable (up to now) 3Mbps profile.

So, from my tests, it would appear that these BT Homehubs do give a good advantage on
connection speeds. It might be noted that my ISP is not BT, but that the exchange does
not have any LLUs - a small rural exchange - so my connection is through the BT
system. Also the BT Homehub that I bought was from eBay and was locked to BT broadband,
but can be unlocked (see http://bt2700hgv.tripod.com/ir1002700HGV.htm).

[waltergmw]

Hi Nick and welcome,

Thanks for your observations which are always valuable on this site.
I too have found the 2Wire BT 2700HGV Business Hub to be very stable on long lines.
However it's worth noting the cautions on web link you gave.
I'm never very happy when auto-updating logic is enabled nor when features could allow others to use the equipment, but sometimes needs must.

You are quite lucky with the speeds you're achieving on a 6 km line length.

Kind regards,
Walter

[jeffbb]

Hi
quote from Walter : You are quite lucky with the speeds you're achieving on a 6 km line length.

normally that distance would equate to over 80db attenuation !!!.
http://www.kitz.co.uk/adsl/max_speed_calc.php
what attenuation do you generally show ?

Regards Jeff

[kitz]

Hi nick and welcome.

Thank you for posting and sharing your experience.   The 2 Wires are considered exceptionally stable for some long lines.  Its a shame that in the UK theres no real retail outlet for them, and we are resorted to flashing the homehubs.

That seems to be an exceptional result for such a long line 


------------


Just a word of warning.. different lines can & do behave differently.. and whilst many times the 2Wires seem to work well for long lines... from my own experience they are a bit of a disappointment on a short line.  In fact on my own line it runs pretty poor when compared to say the ST v6 series and the Netgears with a sync speed of about 2Mb less.

This is aside from the fact that unfortunately they dont support Annex_M so its pretty useless for me giving a total speed loss of circa 3Mb

I keep meaning to take it round to a medium length line to see how it runs on that.. but since that line is now currently running its best ever using a DG834GT, not sure if the owner wants to disturb things right now.

[roseway]

I keep meaning to take it round to a medium length line to see how it runs on that.. but since that line is now currently running its best ever using a DG834GT, not sure if the owner wants to disturb things right now.

Funny you should say that, because I have a medium length line (41 dB attenuation) and stimulated by this thread I've ordered a BT 2700HGV on eBay to see how it performs here. Assuming that I can unlock it successfully I'll report back when I've got it running.

[Edit - model number corrected]

[waltergmw]

Eric,

Just a small caution.

I recently bought 3 BT 2700HGV gateways from 3 different sources. One had a S/N OF 920919131nnn and was therefore manufactured in wk 2 of 2009 has the slightly less favoured new version 6 firmware which cannot (yet) be downgraded to version 5, nor (I believe) can it be poisoned to inhibit BT's generosity of auto-upgrades.

Kind regards,
Walter

[roseway]

Thanks Walter.

[nickdanby]

Having read some of the comments on my experience, I thought that I had better do some more checking. It was a BT engineer who gave me the line distance as over 6Km, but when I measure the distance from the exchange on an 1:25000 ordnance survey map I get about 5.0Km. However that does not basically affect my original findings. For general information, as I write this, the figures from the BT2700HGV are:
Downstream Rate: 3744 kbps 
Upstream Rate: 448 kbps
Current Noise Margin: 6.0 dB (Downstream) 20.0 dB (Upstream)
Current Attenuation: 59.0 dB (Downstream) 31.5 dB (Upstream)
Current Output Power: 19.2 dBm (Downstream) 12.4 dBm (Upstream)
After I started this thread, we have had torrential rain and the Noise Margin did drop to 1dB late in the evening (a time when the margin is normally low), but the line did still not drop out.
As another point, as I said before, I do volunteer work for a rural radio broadband network, and it was the BT Homehubs from them that I was asked to check (for another reason). One of the nodes on this network is in a building opposite and at the moment the sync speed on that is 3776Kbps.

[waltergmw]

Hi again Nick,

It is quite common for BT to have significantly longer lines even than the road distance.
(I know of one horror where the crow-flies distance is about 3 km but the actual line length is over 7 km.)
The GPO installed cables for minimum total copper length so they will frequently detour to pick up additional houses rather than run a new cable from the PCP or exchange.

You might like to check the attenuation figures in the diagnostics section of your modem as this is probably a more accurate reflection of what the modem is actually observing.

Kind regards,
Walter

[djnield]

Just to chip in...

I use the 2700HGV too on a 36db line (O2) and sync around 9500~9800 usually. Occasionally I get a bit more but never have I lost sync with this router, it stays stable in the evenings when my SNR is taking a pounding.

[roseway]

My 2700HGV arrived today, and I've unlocked it using advice from here. I'm using it now, and so far it looks good. Routerstats-Lite works with it, so I'll monitor it for a few days and see how it goes.

[jeffbb]

Hi

@nickdanby: with an attenuation of 59db giving a calculated distance of about 4.3 Km.You would normally expect to synch at something like 2752Kbps  with the default target SNR of 6db .
http://www.kitz.co.uk/adsl/max_speed_calc.php

You are doing very well  You must have an exceptionally quiet line . Even all the other routers were connecting above "normal" synch rate , with figures above 3000Kbps.
Perhaps there are some advantages to being connected to a small rural exchange -

Regards Jeff

[kitz]

I'll just add my findings on a short line that Ive just done.

Speedtouch ST585v6

Uptime:   9 days, 2:57:05
Modulation:   G.992.5 Annex M US 56
Bandwidth (Up/Down) [kbps/kbps]:   2,636 / 22,480
Data Transferred (Sent/Received) [MB/GB]:   561.20 / 4.19
Output Power (Up/Down) [dBm]:   13.0 / 18.0
Line Attenuation (Up/Down) [dB]:   5.5 / 12.5
SN Margin (Up/Down) [dB]:   3.5 / 3.5
Vendor ID (Local/Remote):   TMMB / µ
Loss of Framing (Local/Remote):   0 / 0

2Wire 2700 HG-B

DSL Connection Details
DSL Line (Wire Pair): Line 1 (inner pair)
Protocol: G.DMT2+ Annex A
Downstream Rate: 22273 kbps 
Upstream Rate: 1224 kbps 
Channel: Fast
Current Noise Margin: 3.0 dB (Downstream), 3.6 dB (Upstream)
Current Attenuation: 12.9 dB (Downstream), 5.9 dB (Upstream)
Current Output Power: 16.6 dBm (Downstream), 11.9 dBm (Upstream)
DSLAM Vendor Information: Country: {0xB5} Vendor: {BDCM} Specific: {0x8F91}
PVC Info: 0/101

The 2 wire doesnt do Annex_M, so to make things equal, I put the ST585 back on and switched it to Annex A

Uptime:   0 days, 0:00:39
Modulation:   G.992.5 Annex A
Bandwidth (Up/Down) [kbps/kbps]:   1,399 / 24,156
Data Transferred (Sent/Received) [KB/KB]:   6.00 / 4.00
Output Power (Up/Down) [dBm]:   12.0 / 18.0
Line Attenuation (Up/Down) [dB]:   5.0 / 12.0
SN Margin (Up/Down) [dB]:   3.5 / 3.5

Hence why I dont use it.. (aside from the fact that it doesnt do Annex M,)  but you can see when going head to head on Annex_A it crops a hell of a lot of speed off for me 

[waltergmw]

@ Kitz,

I think many of us know how fiendishly difficult it is (impossible?) to state with any accuracy which is the "best" modem for a particular line.
However there appear to be a set preferences possibly based upon the chipset included, which perhaps could be listed for types of modems for use on particular types of line.
E.g. despite the earlier AR7 bug, AR7 based modems seem to outperform others on very bad lines.

Whilst this topic is always going to be a difficult one to handle, careful selection can make the difference between a broadband service and none at all.
The bottom end of the spectrum is probably much more important to those unfortunates than knowing which modem can be persuaded to add another 200 kbps on an 18 Mbps line.

I wonder if we could produce a page of recommendations for those struggling ? Here are a few ideas to be discussed, the ones with question marks need more detail.

1. Carefully inspect the BT-side wiring, get BT to remove all star wiring and install a NTE5 type terminating unit ensuring cable runs are a minimum of say 100 mm from all mains wiring
2. Always connect the modem to the master socket without any ringwire connected anywhere in the house.
3. Use high quality (active or passive?) filters.
4. Discard any antique-type pulse-dialling and analogue cordless phones on any lines to the house.
5. Use a screened modem lead preferably no longer than 0.5 m.
6. Locate all noise transmitters such as switched mode power supplies, DECT and mobile phones, cordless door bells, remote boiler control units, external PIR lights etc.  as far away as possible.
7. Make a careful selection of the modem from the following list ?
8. Don't attempt to get a NGA-type connection ?
9. In extremis get your ISP to have the line capped at 500 kbps ?

Kind regards,
Walter

[sevenlayermuddle]

without any ringwire connected anywhere in the house.

Walter,

I'd like to see more discussion of that one. 

Clearly it offers benefits  but, as was pointed out recently in another thread, it does leave a non-standard installation.  I know that most modern phones don't need a ring wire, and those that do can get it from a filter even if DSLs not in use, but it could cause problems for future occupiers who don't know that.

The worst scenario I can think of would be a future occupier who didn't want DSL and had a liking for antique pulse dial phones, as these depend on the continuity of the ring wire to stop one another's bells from  tinkling as other phone's dials are operated.

The alternative advice would be to fit an iPlate which leaves the ringwire intact...  have we ever quantified the performance of an iPlate compared to ringwire removal for long lines?

I'd hate to find that a future owner of my house had incurred a charge from BT to sort out what he might regard as 'bodgework' by me.  What do other people think?  Is this worth worrying about?