Talk:Asymmetric Digital Subscriber Line

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That is not true. The theoretical maximum for G.992.1 for example is 13Mbps (224 downstream carriers * 15bit/carrier * 4kHz symbol frequency). --69.105.224.209

Can someone elucidate DSLAM? I suppose it's DSL access apparatus, but abbreviations should be defined before use.

It's explained here --Tolien 3 July 2005 20:17 (UTC)

I understand that "Annex A" is for ADSL over analog lines while "Annex B" is for ISDN lines. Could someone enter this into the article with some info on how likely you are to need one or the other? Or other compatibilities or non-compatibilites to watch out for? Thanks. ---Ransom/CG

Contents 1 Spectrum allocation not quite right 2 Faxes 3 Asynchronous 4 Upload speeds 5 Upload 6 ADSL backbone network 7 Updating ADSL and DSL entries

[edit] Spectrum allocation not quite right

The spectrum breakdown is not entirely accurate in this article. CAP did allocate spectrum the way that the diagram indicates it, but DMT doesn't - it defines 247 (from memory - this figure might be a bit out) subchannels, each of which can be either upstream or downstream (dynamically). --DaveSymonds 06:11, 21 September 2005 (UTC)

Yep, just looked it up: DMT splits the channel into 247 subchannels, each 4kHz wide. This is the standard way it's done now. --DaveSymonds 06:15, 21 September 2005 (UTC)

[edit] Faxes

Out of interest, how does ADSL affect faxes? can you send or receive a fax on an ADSL line? - Ta bu shi da yu 05:34, 14 January 2006 (UTC)

A fax is just a low-speed modem, so it uses the voice band. This band is protected by a splitter from the DSL signal. Biot 09:10, 14 January 2006 (UTC)

That's what I though. Cheers Biot! - Ta bu shi da yu 13:53, 15 January 2006 (UTC)

[edit] Asynchronous

ADSL is a syncronous protocol at the lowest data layer. Amusingly enough, it runs ATM (async transfer mode) on top of this layer, but it still used syncronised clocks at the sending and receiving end.

That is, I think, true of most layers atop which ATM runs. Guy Harris 23:22, 25 November 2006 (UTC)

[edit] Upload speeds

"Upstream rates start at 64 kbit/s and typically reach 256 kbit/s but can go as high as 1024 kbit/s." Is this also true for ADSL2 and ADSL2+? Or do they allow higher upstream rates? --ozzmosis 10:26, 26 February 2006 (UTC)

[edit] Upload

The site only mentions the word "upload" once, maybe more information should be provided about uploading on ADSL, the uploading speed, and if uploading is affected by downloading. etc.--82.152.138.225 01:29, 8 March 2006 (UTC)

What I think you are referring to is "link saturation", where the maximum upload speed obtainable reduces during a high speed download, or vice versa. But this behaviour is not restricted to ADSL. --ozzmosis 12:24, 8 March 2006 (UTC)

Actually, can ADSL upload and download data at the same time, or is it effectively one or the other? --geoff_o 20:35, 11 April 2006 (UTC)

I thought I should point out that in Japan, download speeds for ADSL go as high as 47Mbps, and upload speeds up to 5Mbps. Without the proper technical background, I wouldn't want to alter this article, but I thought it might be useful info to add. For evidence of this see the NTT page, in English, on this: http://www.ntt-east.co.jp/product_e/05/2.html

I believe that the 47/5 Mbps line is propably a bonded ADSL2+ line, in otherwords, two ADSL2+ lines used together for the connection. This is covered in the ADSL2/2+ ITU-standard. But I cannot support this claim with any evidence, it's only a guess because the speeds would match pretty nicely.

This is not correct - in japan "adsl2++" is used , which extends the adsl spectrum to 3.75MHz, thus roughly doubling the downstream rate to 50Mbps. 5 Mbps upstream is with triple upstream - the upstream band is three times the US bandwidth of regular adsl. ~~===

[edit] ADSL backbone network

I was wondering, if its approriate to mention that the shift from ATM backbone networks to Ethernet is also because of the future possibilities of using the same backbone network for other services like POTS or mobile phone networks?

..."or lower signal to noise (SNR)ratios"... Shouldn't this be lower Signal to Noise Ratios(SNR)? Cruxit 15:59, 14 June 2006 (UTC)

[edit] Updating ADSL and DSL entries

CarlosRibeiro 17:23, 21 October 2006 (UTC). I've dropped a note at the DSL history. I moved some notes on DSL installation that applied specifically to ADSL here. It refers to some history on the usage of splitters, that is not longer absolutely required but is still of interest, both historically and also to understand some practical aspects of the technology.