VDSL Attenuation vs PreQual figures

Forums › New Zealand Broadband › VDSL Attenuation vs PreQual figures

ElectronicFerret

125 posts

Master Geek
+1 received by user: 9

#179174 30-Aug-2015 08:59

Hi,
I had a VDSL Prequal done on a line. The line already had a voice service and the Test Termination device (in the ETP) when the prequal was done.

The PreQual came back at 1dB.

I then installed a master XDSL filter and 9 metres of Cat6 cable into a cat6 RJ45 socket. A short (0.3m) RJ45-RJ11 ribbon cable is fitted between the modem and socket.

Modem is reporting 8dB of attenuation.

Is a PreQual attenuation comparable in any way to the final VDSL attenuation figure? Modem output is below

I'm happy with the connection, but if the figures are comparable and I've added 7dB of attenuation to the line, I want to check my connections!

Thanks

Vigor> adsl status

---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------

Running Mode : 8B State : SHOWTIME

DS Actual Rate : 42652000 bps US Actual Rate : 10360000 bps

DS Attainable Rate : 42675056 bps US Attainable Rate : 14773000 bps

DS Path Mode : Interleave US Path Mode : Interleave

DS Interleave Depth : 0 US Interleave Depth : 0

NE Current Attenuation : 8 dB Cur SNR Margin : 11 dB

DS actual PSD : -16.-4 dB US actual PSD : 13. 9 dB

NE CRC Count : 0 FE CRC Count : 0

NE ES Count : 0 FE ES Count : 0

Xdsl Reset Times : 0 Xdsl Link Times : 3

ITU Version[0] : b5004946 ITU Version[1] : 544e0000

VDSL Firmware Version : 05-04-08-00-00-06

Power Management Mode : DSL_G997_PMS_L0

Test Mode : DISABLE

-------------------------------- ATU-C Info ---------------------------------

Far Current Attenuation : 0 dB Far SNR Margin : 15 dB

CO ITU Version[0] : b5004244 CO ITU Version[1] : 434da3f5

DSLAM CHIPSET VENDOR : < BDCM >

Vigor>

1 | 2

361 posts

Ultimate Geek
+1 received by user: 74

#1376287 30-Aug-2015 09:06

I assume you have a vigor 130, with the latest firmware Dsl-Stats are on the menu diagnostics/dsl status

sbiddle

30853 posts

Uber Geek
+1 received by user: 9996

Retired Mod

Trusted

Biddle Corp

Lifetime subscriber

#1376290 30-Aug-2015 09:12

Chorus prequal data is based off network testing during the cabinetisation project. It is not a realtime test.

ElectronicFerret

125 posts

Master Geek
+1 received by user: 9

#1376328 30-Aug-2015 10:00

sbiddle: Chorus prequal data is based off network testing during the cabinetisation project. It is not a realtime test.

We're still on an exchange, but this probably still applies. Thanks, that's very useful to know.

BMarquis

465 posts

Ultimate Geek
+1 received by user: 577

Trusted

Chorus

Lifetime subscriber

#1376342 30-Aug-2015 10:33

ElectronicFerret:
sbiddle: Chorus prequal data is based off network testing during the cabinetisation project. It is not a realtime test.

We're still on an exchange, but this probably still applies. Thanks, that's very useful to know.

This is one of those rare times where Mr. Biddle is not quite right.

The main thing is that the pre-qual attenuation will never be the same as what your modem reports.
Pre-qual is theoretical attenuation at a specific frequency.

ElectronicFerret

125 posts

Master Geek
+1 received by user: 9

#1376386 30-Aug-2015 12:35

BMarquis:
The main thing is that the pre-qual attenuation will never be the same as what your modem reports.
Pre-qual is theoretical attenuation at a specific frequency.

So would it be reasonable for a 1dB prequal to end up being 8dB on VDSL? Or have I created a problem during my Master filter install?

Spyware

3818 posts

Uber Geek
+1 received by user: 1366

Lifetime subscriber

#1376387 30-Aug-2015 12:38

ElectronicFerret:
BMarquis:
The main thing is that the pre-qual attenuation will never be the same as what your modem reports.
Pre-qual is theoretical attenuation at a specific frequency.

So would it be reasonable for a 1dB prequal to end up being 8dB on VDSL? Or have I created a problem during my Master filter install?

I have an 8 dB connection at work and it syncs at 70/10. Cabinet is 300 or so meters away following road.

Spark Max Fibre using Mikrotik CCR1009-8G-1S-1S+, CRS125-24G-1S, Unifi UAP, U6-Pro, UAP-AC-M-Pro, Apple TV 4K (2022), Apple TV 4K (2017), iPad Air 1st gen, iPad Air 4th gen, iPhone 13, SkyNZ3151 (the white box). If it doesn't move then it's data cabled.

Geekzone

Want to support Geekzone and browse the site without the ads? Subscribe to Geekzone now (monthly, annual and lifetime options).

JeremyNzl

361 posts

Ultimate Geek
+1 received by user: 74

#1376388 30-Aug-2015 12:41

Are you connections Naked ?

If so no masterfilter required

Jase2985

13730 posts

Uber Geek
+1 received by user: 6202

ID Verified

Lifetime subscriber

#1376400 30-Aug-2015 13:22

different devices report different figures. my spark supplied technicolor one said 6.3dB, my netcomm NF8AC says 8.6dB. Same connection speed.

JeremyNzl: Are you connections Naked ?

If so no masterfilter required

yes and no, a master filter install eliminates all the other phone wiring from the VDSL line. on a naked install you dont need the mast filter, but you need to remove all the other phone jacks from the equation to eliminate stubs and reflections they can cause. so they pretty much do the same thing. eliminate the house wiring as being a cause of a slow connection.

BMarquis

465 posts

Ultimate Geek
+1 received by user: 577

Trusted

Chorus

Lifetime subscriber

#1376404 30-Aug-2015 14:03

Spyware:
ElectronicFerret:
BMarquis:
The main thing is that the pre-qual attenuation will never be the same as what your modem reports.
Pre-qual is theoretical attenuation at a specific frequency.

So would it be reasonable for a 1dB prequal to end up being 8dB on VDSL? Or have I created a problem during my Master filter install?

I have an 8 dB connection at work and it syncs at 70/10. Cabinet is 300 or so meters away following road.

I wouldn't want to try and guess if that is reasonable or not, as the figures of 1 and 8 there don't realte at all.
Your best bet is to hook the modem up at the ETP, and see if the sync rate is any different.

coffeebaron

6304 posts

Uber Geek
+1 received by user: 3567

Trusted

Lifetime subscriber

#1376409 30-Aug-2015 14:17

If I read your stats correctly, 4Mbps down? Then either:
1 your master filter install has mucked up something
2 there is a major fault on your line
3 you are way beyond the reach of VDSL

Rural IT and Broadband support.

Broadband troubleshooting and master filter installs.
Starlink installer - one month free: https://www.starlink.com/?referral=RC-32845-88860-71
Wi-Fi and networking
Cel-Fi supply and installer - boost your mobile phone coverage legally

Need help in Auckland, Waikato or BoP? Click my email button, or email me direct: [my user name] at geekzonemail dot com

Jase2985

13730 posts

Uber Geek
+1 received by user: 6202

ID Verified

Lifetime subscriber

#1376411 30-Aug-2015 14:24

coffeebaron: If I read your stats correctly, 4Mbps down? Then either:
1 your master filter install has mucked up something
2 there is a major fault on your line
3 you are way beyond the reach of VDSL

your maths is wrong by a factor of 10

Samsung

Shop now on Samsung phones, tablets, TVs and more (affiliate link).

Coil

6614 posts

Uber Geek
+1 received by user: 2153
Inactive user

#1376414 30-Aug-2015 14:36

Confirmed

So many variables with speed. Attenuation is one thing, Quality of the copper, cross talk, modem, SNR.....

coffeebaron

6304 posts

Uber Geek
+1 received by user: 3567

Trusted

Lifetime subscriber

#1376418 30-Aug-2015 14:44

Jase2985:
coffeebaron: If I read your stats correctly, 4Mbps down? Then either:
1 your master filter install has mucked up something
2 there is a major fault on your line
3 you are way beyond the reach of VDSL

your maths is wrong by a factor of 10

Ah, indeed after a closer look. So OP already on VDSL.

Rural IT and Broadband support.

Need help in Auckland, Waikato or BoP? Click my email button, or email me direct: [my user name] at geekzonemail dot com

Coil

6614 posts

Uber Geek
+1 received by user: 2153
Inactive user

#1376421 30-Aug-2015 14:48

coffeebaron:
Jase2985:
coffeebaron: If I read your stats correctly, 4Mbps down? Then either:
1 your master filter install has mucked up something
2 there is a major fault on your line
3 you are way beyond the reach of VDSL

your maths is wrong by a factor of 10

Ah, indeed after a closer look. So OP already on VDSL.

Quite good figures too :).

Most of my VDSL lines have been around 30-50Mb/s before tweaking.

RunningMan

9185 posts

Uber Geek
+1 received by user: 4838

#1376492 30-Aug-2015 17:29

JeremyNzl: Are you connections Naked ?

If so no masterfilter required

A common myth, but not quite true. This is only the case if you have a complete transmission line from the etp to the outlet - a single outlet with no branches, used or unused. If not, you still need the master filter, even on naked or the existing wiring will have a negative impact on xDSL sync rates.

1 | 2