Kitz Forum

Internet => Interesting Websites => Topic started by: Weaver on October 14, 2019, 01:02:33 AM

Title: Britannia article
Post by: Weaver on October 14, 2019, 01:02:33 AM
In this article https://www.britannica.com/technology/modem/DSL-modems should the standard for ADSL not be G.992.1 ? Not G.991.2 as stated ? Or am I missing something? Was the latter earlier? The thing is, it does explicitly mention asymmetrical rates in the article.
Title: Re: Britannia article
Post by: burakkucat on October 14, 2019, 01:37:56 AM
ADSL   is ITU-T G.992.1
ADSL2  is ITU-T G.992.3
ADSL2+ is ITU-T G.992.5
VDSL   is ITU-T G.993.1
VDSL2  is ITU-T G.993.2

  :graduate:
Title: Re: Britannia article
Post by: sevenlayermuddle on October 14, 2019, 09:49:27 AM
Not sure the comparison with T1 is helpful.

Quote
DSL systems carry digital signals over the twisted-pair local loop using methods analogous to those used in the T1 digital carrier system to transmit 1.544 Mbps in one direction through the telephone network.

T1 is an entirely different technology, using TDM,  not DMT.  The USP of T1, from my hazy recollection, is the ability to multiplex 24 discreet timeslots (32 for E1), each of which has individual bandwidth as required for a single voice channel, onto a single line.
Title: Re: Britannia article
Post by: dee.jay on October 14, 2019, 08:58:46 PM
I have experience with E1 (European equivalent of T1) for voice, used to operate a Cisco CallManager over an E1 ISDN PRI interface on a Cisco 2600 router.

We had 16 channels, so could make that many external calls at once out to the PSTN, IIRC.

Fun times.
Title: Re: Britannia article
Post by: burakkucat on October 14, 2019, 09:19:11 PM
I have now read that article all the way from the Introduction to the end and my feeling is the author has somewhat "lost his way".  :-\  :-X
Title: Re: Britannia article
Post by: sevenlayermuddle on October 14, 2019, 09:32:53 PM
E1 is not just Europe, iirc pretty much everywhere uses E1, other than North America or Japan.

Quote from: burakkucat on October 14, 2019, 09:19:11 PM
I have now read that article all the way from the Introduction to the end and my feeling is the author has somewhat "lost his way".  :-\  :-X

Your attention span is better than mine, I failed to get very far.   But your conclusion does not surprise me. :)
Title: Re: Britannia article
Post by: burakkucat on October 14, 2019, 10:33:37 PM
Quote from: sevenlayermuddle on October 14, 2019, 09:32:53 PM
But your conclusion does not surprise me. :)

b*cat bows to 7LM in acknowledgement of the compliment.
Title: Re: Britannia article
Post by: Weaver on October 15, 2019, 12:21:08 AM
@burakkucat - agreed - so it wasn’t just me then?
Title: Re: Britannia article
Post by: burakkucat on October 15, 2019, 12:23:28 AM
Agreed. No, it wasn't you.
Title: Re: Britannia article
Post by: niemand on January 07, 2020, 01:20:33 AM
Quote
By varying the number of carriers actually used, DMT modulation may be made rate-adaptive

So nothing to do with changing the modulation order used in individual tones, just on or off. Right-o.