Talk:Asymmetric Digital Subscriber Line

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Contents

[edit] Provider Section

The Suppliers section seems to be very short. I will be adding more Suppliers of ADSL/DSL services. Ishmael Rufus 16:18, 1 June 2007 (UTC)

[edit] vs DSL

Is this better than DSL? What abuot cable? Whats the difference? Is it big or small?


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

[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.

[edit] Is it an analogue or digital technology?

Hello

Is it correct to describe it as a digital technology since it modulates analogue carriers?

Thanks

I.I.A —The preceding unsigned comment was added by 195.130.120.24 (talk) 09:03, 21 December 2006 (UTC).

[edit] Annex M

The page here states the download speed is 28mbit, but the [[ITU G.992.5 Annex M] page says 24mbit... which is it? 125.236.153.184 09:05, 31 January 2007 (UTC)

[edit] Capitalization

Reading [1] I think it means this article is incorrectly capitalised, while Digital subscriber line is correctly titled. Does anyone agree that only the first word should be capitalized? Disagree? Think both styles are correct for their respective article? Jim.henderson 20:29, 19 March 2007 (UTC)

[edit] S=1/2?

My USR router specs says that with S=1/2, it can do 12Mbps, up from 8. What does S=1/2 mean and how does it extend the download speed? Any info appreciated, cheers! 84.9.32.226 14:47, 25 June 2007 (UTC)

[edit] OFDM system comparison table

Feel free to add an ADSL column to the OFDM#OFDM system comparison table. Mange01 11:46, 17 July 2007 (UTC)


[edit] History

I came to this page to find out when ADSL was invented and rolled out. If someone knows, can they add it to the article? It would also be good to know who invented it. exterminator 11:06, 8 August 2007 (UTC)

[edit] How Much Faster is ADSL compared to Dialup?

I came here hoping to find a definitive answer, because Verizon's claims make no sense ("768 kbit/s DSL is 21 times faster than 56k dialup"). 768/56 == 13 which is nowhere near Verizon's claim. (It's even less when you consider 56K modems use compression to increase effective thoughput to ~150 kbps).) I'd like to find an actual study that's not biased by salesmanship. - Theaveng 17:37, 14 September 2007 (UTC)

Given that ADSL can run from 768Kb/s (or possibly even lower) to 6Mb/s (or possibly even higher), there isn't a single definitive answer to your question. I've gotten 1.5Mb/s; 1500/56 = 26. Guy Harris (talk) 19:21, 20 November 2007 (UTC)

Typical marketing flim-flam, probably. Remember that the max tech speed of this segment of the SYSTEM that you are using is only one factor in the response you experience. Your computer is a factor. Latencies anywhere along the way are a factor, that remains no matter how fast the peak speeds. As a practical matter, you can hope that DSL will be about ten times faster than dial-up, in real life. -69.87.200.195 (talk) 11:17, 24 March 2008 (UTC)

[edit] Does DSL use V.42, V.44, or some other data compression?

My dialup modem uses V.44 to compress text 6-to-1 (effective throughput of 300 kbit/s) and executables like flash programs 3-to-1 (effective throughput of 150 kbit/s). Does DSL use a similar technology to squash data on the fly? - Theaveng (talk) 18:30, 20 November 2007 (UTC)

[edit] Installation issues

I think this part is about how it is done in the USA? This can be very different depending on local telephone installations in other parts of the world.

Example: ADSL is very in wide use in Germany now and local installation is usually done by the customer, but I have never heard of a microfilter. When you order ADSL you get a spitter from your provider and you install it yourself by pluging it into the telephone jack. The splitter is the only device directly connected to the public network. The splitter itself has two outputs, one for a DSL modem and one for a telephone or an ISDN network termination device. Since the combination of ADSL+ISDN is very common in Germany , there are combined spliiter/termination boxes (called "NTSplit" or something), sometimes there is even a small ISDN PBX inside that box.

I think microfilters make sense if you have multiple telefone jacks that are simply wired parallel. This kind of installation is not even allowed here. If you want more than one telefone you use a small PBX (or ISDN devices connectes to a S0 bus) with the ADSL splitter in front.

Christian —Preceding unsigned comment added by 80.133.139.40 (talk) 15:51, 15 January 2008 (UTC)


Filters are not necessary for ISDN lines, which do not have a large ringer condenser producing echoes. ISDN is rare in the USA, and almost non existent in American homes. Are the German DSL splitters separately marked with a phone socket and a modem socket?
Yes, the splitter has 3 Connections: An input for the old phone jack (the splitter is the only device connected to the public network) and 2 Outputs: One is for the modem, the other one is for telephone equipment.
Is the German arrangement different when DSL is applied to an old analog line?
No, as far as I know all providers in Germany use ANNEX-B DSL ("DSL over ISDN") even when there is no ISDN but an analog phone line. One of the reasons is historic, for several years you could only get DSL in combination with ISDN. Now you can also get it with analog, but they use the same equipment.
Most splitters have a small switch ("ISDN - ANALOG") so the same device could be used for ANNEX-A on an analog line, giving some more bandwidth, but the telcos don't use that and the devices are shipped configured to ISDN (ANNEX-B). I think they also want to avoid customer confusion. (Christian)

[edit] OSI Model

Where in the OSI model do (A)DSL and ADSL+ fit? In the link layer? —Preceding unsigned comment added by 194.251.240.114 (talk) 12:42, 7 February 2008 (UTC)

[edit] 768Kbps

It is great to have all this tech info about the range of possible speeds. But it would be good to also have a table of the most common marketed speeds. In the US 2008 at the low end for Verizon that is 768 Kbps / 128 Kbps. It would be interesting to see a table of the most common low-end DSL speeds current around the world, and the average price. -69.87.200.195 (talk) 11:11, 24 March 2008 (UTC)

[edit] Annex L footnote

The footnote for Annex L seems to be ineditable. I was one of the contributors to that bit of text, and I think it should probably be changed a bit by now, but that doesn't seem to be possible anymore, or am I missing something? KryzMasta (talk) 21:55, 8 April 2008 (UTC)

I just clicked on the Edit key for the table, and shortened the footnote without diffuclty. Maybe someone fixed the problem and didn't say. Jim.henderson (talk) 21:31, 14 April 2008 (UTC)