dslreports logo
 
    All Forums Hot Topics Gallery
spc
Search similar:


uniqs
94787

john2009
@covad.net

john2009

Anon

Line Mode: G.DMT Mode, ADSL2+ Mode?

whats the difference between this 2 line mode?
Line Mode: ADSL2+ Mode
Line Mode: G.DMT Mode

Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium Member
join:2001-04-19
1970 442 W30

1 edit

Doctor Olds

Premium Member

Older original DSL is G.DMT and/or ANSI T1.413 (up to 8 Mbps Downstream/up to 1 Mbps Upstream) and both are fully interchangeable. Also called "Full Rate" ADSL.

See chart above for ADSL2+ info.

These explain the Frequencies used and the different ranges.





Regards,

Doctor Olds

john2009
@covad.net

john2009 to john2009

Anon

to john2009
so adsl2+ gives you better up and down stream margin then G.DMT ?

Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium Member
join:2001-04-19
1970 442 W30

Doctor Olds

Premium Member

said by john2009 :

so adsl2+ gives you better up and down stream margin then G.DMT ?
No, not at all. Just the opposite. The faster you go the more stress and demand is placed in the entire line and even more so on the inside wiring.

ADSL2+ drops speed dramatically as distance increases since the ADSL2+ places 4 times the load demands on the line.

If you have a Marginal ADSL line that get less than 1.0, then you are not going to see any miracles from ADSL2+.


Notice ADSL2+ only adds just under 2k feet to the total length of regular ADSL.


ADSL2+ speeds are best at under 6k Feet.


ADSL2+ doubles the ADSL2 Bandwidth




Regards,

Doctor Olds

Splitpair
Premium Member
join:2000-07-29
Cow Towne

Splitpair

Premium Member

said by Doctor Olds:

The faster you go the more stress and demand is placed in the entire line and even more so on the inside wiring.Regards,

Doctor Olds
It's actually the other way around the loop places a load (loss, distortion, multi-path echo’s etc.) upon the ADSL signal as the signal is incapable of doing anything to the copper that carries it. The demand if there was one would be placed on the DSP and the algorithm running the DSP in the ADSL(2)(+) receiver in the DSLAM/modem to sort usable bits out of the received signal.

BTW stress on a copper loop is a factor of DC flowing thru the loop and causing noise at less than perfect splices which will only affect xDSL in an off hook condition.

FWIW ADSL2(+) simply places additional bins above the ADSL cutoff of bin number 254 this extends the upper limit of the signal almost an additional meg to just over 2mHz.

In order to prevent additional NEXT as a result of the higher transport frequencies the downstream output power is reduced in a ratio to the increase of frequency.

This lowering of power actually pulls in not extends the SCA that ADSL2 (+) will work at. As such once one gets into loops over 8-10 Kf non-bonded ADSL2 can have a lower thru-put than standard ADSL.

Wayne

Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium Member
join:2001-04-19
1970 442 W30

Doctor Olds

Premium Member

Thanks for the in-depth clarification.

john2009
@covad.net

john2009 to john2009

Anon

to john2009
ok thx for clearing that out guys.
My current statue of the line
margin for download usually stays at 24.0 upload usually stays at 17.0
margin fluctuate alot time from 24 db to goes down to 7 db for download margin is this normal? or something is wrong?

Line Mode: ADSL2+ Mode
Data Path: Interleaved
Transceiver Information Down Stream Path Up Stream Path
DSL Speed (Kbits/Sec) 6013 767
Margin (dB) 21.0 15.0
Line Attenuation (dB) 18.0 9.5
Transmit Power (dBm) 19.5 12.2

jamez818
please hold during the silence
join:2000-09-18
Sunland, CA

jamez818 to john2009

Member

to john2009
My Down margin fluctuates as well. Upload always seems to be ok. Its an easy fix, just restart the modem and the margin goes back up and stays like that for the rest of the day. I usually get up in the morning and automatically restart my modem out of habit now.
Up
noise margin upstream: 13 db
output power downstream: 22 db
attenuation upstream: 14 db
Down
noise margin downstream: 19 db
output power upstream: 12 db
attenuation downstream: 27 db

Upstream Speed: 1023 kbps
Downstream Speed: 7996 kbps
Expand your moderator at work
oregonexile
join:2004-08-18
Decatur, GA

oregonexile to john2009

Member

to john2009

Re: Line Mode: G.DMT Mode, ADSL2+ Mode?

I am at or around 18,000 ft from the CO. I've had good days and bad days. At one time, I used to get 1.5Mbps, but I am happy now just to get the following:

ADSL Connection Up
Resync Count 18
ADSL Mode G.DMT
Downstream Bit Rate 320 Kbps
Upstream Bit Rate 256 Kbps
Downstream Capacity Occupation 90 %
Downstream Noise Margin 6.02 dB
Downstream Attenuation 63.98 dB
Downstream Output Power 14.13 dBm
Upstream Capacity Occupation 38 %
Upstream Noise Margin 13.00 dB
Upstream Attenuation 31.50 dB
Upstream Output Power 11.97 dBm

I've tracked down every possible source of interference, and have to conclude that I am too far from the CO to get reliable connectivity. DSL splitter outside, and weather proof CAT 5e to the modem all running in the crawl space away from electric lines or cross perpendicular when not possible. Somebody has to represent the backside of the bell curve...