New Modem - possible tweaks needed?

Hi,

I just bought a new Billion 7800N and got it up and running with my ADSL2+ connection (BT). The status looks like this:

Parameters
DSP Firmware Version A2pB025f.d22k
DMT Status No Defect
Operational Mode G.DMT
Upstream 448
Downstream 5824
SNR Margin(Upstream) 19.0
SNR Margin(Downstream) 10.0
Line Attenuation(Upstream) 25.5
Line Attenuation(Downstream) 41.0

I'm not sure if these are good/bad/indifferent, or what I can do (if anything) to improve them. Can anyone check them over and give me some advice?

Thanks.

For starters you're not running on ADSL2+, on which you could get about 8 Meg.

No point in tweaking until you get on ADSL2+ and see what it delivers.

You sure your exchange (which one?) does ADSL2+?

I'm not?

The exchange is, yes. At least it's listed on BT Wholesale as being ADSL2+. It's Ely, Cambridgeshire.

Edited by deleted (Mon 16-Jul-12 20:46:40)

Definitely not on ADSL2+. G.DMT is plain ADSL, and the 448kbps upload is the norm for plain ADSL but pretty well never seen on ADSL2+. Check what the mode setting is in your Billion.

The downstream noise margin is also very high and costing a lot of speed. Have you done a lot of reconnections in a short time, trying to get it as you want? That could have caused it.

As XRaySpeX says, you should be connecting at approaching 8Mbps. ADSL2+ should be well over 8Mbps. What did you connect at before you put in the Billion?

Edited by RobertoS (Mon 16-Jul-12 20:53:39)

It's quite simillar to what it was before, just a fraction faster either due to the new modem or due to the new Cat 5e ethernet cable I bought (or both, or neither). All I've done recently is disconnect existing modem and connect the new one.

Settings for the mode page on the Billion look like this:

ADSL Mode: Annex M is checked.
Modulator: All of ADSL2, ADSL2+ G.Lite, T1.413, G.Dmt are checked
Capability: SRA Enable is unchecked
PhyR: Upstream, Downstream are both unchecked.

Ok just chatted to BT person and my profile is ADSL, although the exchange supports ADSL 2. According to the support person:

"Our test indicates that your line currently supports an estimated ADSL Max broadband line speed of 5.5Mbps; typically the line speed would range between 4.5Mbps and 6.5Mbps.

Our test also indicates that your line currently supports an estimated ADSL2+ broadband line speed of 5.5Mbps; typically the line speed would range between 3Mbps and 8Mbps."

That's a total fob-off, read from this site. Those figures are normally under-estimates.

Did he tell you why you aren't on ADSL2+?

Ah - yes, someone else recently got told they weren't on ADSL2+ because it wouldn't benefit them. Well in your case it would. The line stats tell us the truth about your line. That info is just from a known-to-be dodgy database.

Try putting your stats into this checker, then this one, and take a look at this graph and then this one. If you want to be cautious, on the graphs look at 44dB attenuation for the ADSL2+ figures, as you often find attenuation goes up by 3dB on a move from ADSL to ADSL2+.

Have a look at this page, particularly re G.DMT and ADSL2+. (On the right).

The default noise margin immediately after connecting is 6dB. Some time, reconnect and read the stats immediately. Better done in daylight though, (or repeated then if you do it now). You will probably get a lower speed at night that in the daytime.

My line:-

Our test also indicates that your line currently supports an estimated ADSL2+ broadband line speed of 3.5Mbps; typically the line speed would range between 2Mbps and 6Mbps. Our test also indicates that your line could support an estimated ADSL 2+ Annex-M broadband upstream line speed of 500Kbps and downstream line speed of 3.5Mbps; typically the downstream speed would range between 2Mbps and 6Mbps.

Our test also indicates that your line currently supports a fibre technology with an estimated WBC FTTC Broadband where consumers have received downstream line speed of 51.7Mbps and upstream line speed of 13.2Mbps.

6Mbps was normal for me on ADSL2+. My current FTTC connection speeds are 56626/14078kbps.

Edited by RobertoS (Mon 16-Jul-12 22:34:42)

Fascinating stuff. It looks like I can get a considerable boost from being given the ADSL2+ profile. It's not that I'm being fobbed off, more that I've been a customer for six years here and have never questioned it. Presumably they don't automatically upgrade people when they upgrade the exchange but would do for new customers.

I'll have to call sales then, to see what I have to do to get the correct profile.

In reply to a post by RobinsonUK:

"Our test indicates that your line currently supports an estimated ADSL Max ... typically the line speed would range between 4.5Mbps and 6.5Mbps.

Our test also indicates that your line currently supports an estimated ADSL2+ ... typically the line speed would range between 3Mbps and 8Mbps."

The top end of those ranges are most appropriate for your line. So ADSL2+ is beneficial for you over ADSL Max.

Remember your Down Attenuation will probably rise by 3 dB on ADSL2+.

Remember your Down Attenuation will probably rise by 3 dB on ADSL2+.

Sorry to divert the thread slightly, You say 'Downstream Attenuation will probably rise by 3dB on ADSL2+'. Is this dependent on how the router handles and reports the higher frequencies? I ask, because my Apple Airport Extreme still reports the 28dB downstream Attenuation that it did on ADSL1, but my Billion 7800N now shows 31dB.
I realize routers vary in their reported figures, but I have one that has hung onto the same attenuation.

You can only really compare attenuation figures on ADSL and ADSL2+ on the same router, or perhaps the same model. Even ones using the same main chipset can vary, for example Thomson and Netgear can differ.

I don't think any of us have found why most moves from ADSL to 2+ seen on these forums get a 3dB'ish rise, but a substantial minority don't. I tend to agree with your thought that it is something to do with the reporting of the attenuation on the higher frequencies, but can't find any evidence to support that. We do kknow of course that those fequencies attenuate much faster than the ADSL ones.

It's an empirical fact as far I'm concerned. Dunno the technical reasoning behind it and not too interested,

I assume the same router.

So I called them and have a new contract, to be activated next week. That will put me on the ADSL2+ at the exchange. Still not sure why my line attenuation is so high given that I'm less than 1km from the exchange. Nothing I can do about that is there?

If you have an Airport extreme reporting an attenuation then you have an very unusual model, since it only has an Ethernet WAN interface.

In reply to a post by RobinsonUK:

So I called them and have a new contract, to be activated next week.

You've been had! You should just have been moved to ADSL2+ on your existing terms. Like everybody else. It may be that you would have moved over automatically anyway in a couple of weeks,(in which case you should have been told that), or it may be you would have needed to get to pay about £11 for an express move taking two days, but it sounds as though you've been conned.

If that doesn't bother you, then no harm done.

Re the high noise margin, read this page so that you know what it is and what it does.

After that, read this one.

In reply to a post by MrSaffron:

If you have an Airport extreme reporting an attenuation then you have an very unusual model, since it only has an Ethernet WAN interface.

Well I have only ever owned one model (MD031ll/A) which as far as I know is far from unusual. Post 7 here http://forums.whirlpool.net.au/archive/1730256 shows exactly the same info shown on mine.

Edited by professor973 (Tue 17-Jul-12 10:43:48)

Im on ADSL2+ and no hardware changes have been done, everything is as original. I have a Speedtouch 536v6 supplied by Telstra connected to an Apple AirPort Extreme router in Bridge mode.

Stats there are from the Speedtouch.

In reply to a post by RobertoS:

You've been had! You should just have been moved to ADSL2+ on your existing terms. Like everybody else. It may be that you would have moved over automatically anyway in a couple of weeks,(in which case you should have been told that), or it may be you would have needed to get to pay about £11 for an express move taking two days, but it sounds as though you've been conned.

Naaa, I don't think so. The new contract is actually cheaper than my existing one (by about £4 per month). Obviously after 12 months that will go up because the first year has a discount (by £6.25). So after 1 year, I'll possibly be £2 per month worse off (boo).

I can't believe the line rental price: £14.50 per month? It's kind-of annoying that I have to pay a "rental" for the line at all. I mean I don't pay "rent" for my mobile. Without the line they can't deliver the broadband anyway!

Ah, so in my case, the stats reported in the Airport are those from the connected Draytek Vigor 120. Nonetheless, as I stated, this setup is still holding ADSL1 Attenuation figures where the Billion has jumped 3 points to 31dB. Either way no problem, I was just wondering if various routers handled the higher frequency losses better than others.

In reply to a post by professor973:

Either way no problem, I was just wondering if various routers handled the higher frequency losses better than others.

I reckon so. I also believe it affects the sync. I found the sync difference between routers roughly corresponded to the attenuation difference.

OK, I may be wrong here but:

ADSL2+ uses additional frequencies than ADSL and those frequencies are in a higher range. The attentuation figures are calculated based on the whole range of frequencies. Higher frequencies over any medium attenuate at a higher rate than lower frequencies (which is why mobile phone companies prefer lower frequencies because they travel better through air and building structures).

So, when the higher frequencies are added in to the attenuation map it results in a higher attenuation overall.

Now that could of course be complete rubbish but I am pretty sure it is not.

In reply to a post by RobinsonUK:

I can't believe the line rental price: £14.50 per month? It's kind-of annoying that I have to pay a "rental" for the line at all. I mean I don't pay "rent" for my mobile. Without the line they can't deliver the broadband anyway!

The cost of installing and maintaining the copper pair has to be recovered somewhere - would you like it included in your ADSL charges? they would then be a lot higher each month.

You can, of course, pay BT line rental for a year up front which works out at about £10.50 or so (or it did when I did mine).

There is a difference between telephone line rental which pays for the rental and maintenance of the physical line and exchange equipment and a mobile phone where if you don't use the phone you incur minimal costs to the provider.

Whether the mechanism of charging of line rental untimately to OR is a matter for much debate. Personally I would prefer if OpenReach provided the line, that you paid for, and any services (including voice) where chargeable by the service provider. This would make "naked DSL" and "full fibre" much easier to provide and would make VOIP a viable technology.

Spot on.
Some routers may actually report the attenuation at 300KHz, rather than across the whole spectrum in use too.

The 2wire 2700/2701 family report Downstream Attenuation at 300kHz and also the Attenuation across the whole of the band that is in use which is fairly dynamic.

Similarly the noise level is normally measured across the full spectrum and that used to give the SNR/Margin. I did see one non-UK version of 2wire User Interface which reported noise figures and several specific frequencies - in both up and down bands.