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Standard User nelix01
(committed) Fri 28-Oct-11 07:27:44
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Re: vDMT


[re: Croftie] [link to this post]
 
I'm actually 8.3km from the exchange.

Standard User Croftie
(member) Fri 28-Oct-11 16:24:41
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Re: vDMT


[re: nelix01] [link to this post]
 
Right ok thanks.
Standard User lockyatlrg
(fountain of knowledge) Fri 28-Oct-11 17:55:14
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Re: vDMT


[re: Croftie] [link to this post]
 
at the distance from the exchange I would say your cab is using a different mask to people closer to the exchange.

BT Infinity
ROUTER:-Netgear WNDR37AV
JDSU Stats
Sync 39999D 9995U
Attenuation: 9.6 SNR: 11.4
Line Length 300meters


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Standard User Croftie
(member) Mon 31-Oct-11 01:34:56
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Re: vDMT


[re: lockyatlrg] [link to this post]
 
Yes but nelix is further from the exchange than me, yet has higher power output.

My d-side is longer so I'm thinking the power output reported by the modem doesn't include the e-side.
Standard User burakkucat
(committed) Mon 31-Oct-11 02:01:39
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Re: vDMT


[re: Croftie] [link to this post]
 
My d-side is longer so I'm thinking the power output reported by the modem doesn't include the e-side.
Correct. The modem (the active CPE) and the DSLAM (in the FTTC) are the two devices at either ends of your VDSL2 link.

-----------------------------------------------------

100% Linux and, previously, Unix.
Standard User planetf1
(experienced) Mon 31-Oct-11 22:29:37
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Re: vDMT


[re: burakkucat] [link to this post]
 
Ok, here's my stats. Supposedly my line is around 470m 0.5mm Cu. I can see I'm on the new profile and getting max sync on the current service -- previously my throughput was "only" 34-35 Mbps instead of now peaking around 38.

When the BT engineer installed my line in January he suggested I'd get 70 Mbps in the future (he had worked on these trials for a few years and new his vdsl stuff) so that's not far off what the modem reckons assuming current snr targets.. and of course it could go down with crosstalk frown

# xdslcmd info --show
xdslcmd: ADSL driver and PHY status
Status: Showtime
Retrain Reason: 0
Max: Upstream rate = 24622 Kbps, Downstream rate = 67492 Kbps
Path: 0, Upstream rate = 10000 Kbps, Downstream rate = 39998 Kbps

Link Power State: L0
Mode: VDSL2 Annex B
VDSL2 Profile: Profile 17a
TPS-TC: PTM Mode
Trellis: U:ON /D:ON
Line Status: No Defect
Training Status: Showtime
Down Up
SNR (dB): 14.1 22.3
Attn(dB): 0.0 0.0
Pwr(dBm): 13.8 6.9
Standard User Croftie
(member) Mon 31-Oct-11 23:00:47
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Re: vDMT


[re: burakkucat] [link to this post]
 
Thanks burakkucat, I initially thought there was a single power level between exchange-DSLAM-CPE.
Standard User burakkucat
(committed) Tue 01-Nov-11 01:58:47
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Re: vDMT


[re: Croftie] [link to this post]
 
You're welcome. smile

So, to recap, the only thing that uses the E-side copper is your analogue voice service (POTS / PSTN).

-----------------------------------------------------

100% Linux and, previously, Unix.
Standard User Croftie
(member) Tue 01-Nov-11 21:08:28
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Re: vDMT


[re: burakkucat] [link to this post]
 
Indeed, there is a power level on the fibre E-Side aswell isn't there?
Standard User burakkucat
(committed) Tue 01-Nov-11 22:33:47
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Re: vDMT


[re: Croftie] [link to this post]
 
Er, I see there is a little confusion. wink

When talking about the E-side and the D-side, we are just referring to the copper (or aluminium) cabling to the exchange or to the customers premise from the PCP.

In your case, a FTTC user, there is just 50V DC with the analogue voice signal superimposed upon it that traverses the E-side cable. On the D-side cable, from the PCP to your SSFP, there are three components -- 50V DC, the analogue voice signal and the VDSL2 signal (at radio frequencies).

The VDSL2 power level between the FTTC DSLAM and the active CPE (the Huawei HG612), through the D-side copper (or aluminium) link, has already been mentioned.

You are correct that there is another pair (Tx / Rx) of power levels to be considered. However this is not through the E-side cable but is through the fibre optic feed to/from the FTTC DSLAM from/to its source -- which may not necessarily be the same exchange building to which the E-side cables are connected!

-----------------------------------------------------

100% Linux and, previously, Unix.
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