Acceptable line attenuation for VDSL?

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DS248

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#139214 31-Jan-2014 15:05

From another thread

sbiddle: Direct distance to a cabinet means very little ...

What is the customer's attenuation? ....

We are on ADSL2+ (Vodafone) and had a Chorus tech turn up this morning to switch us onto VDSL. However, he said we are too far from the cabinet so would not install.

We had checked our address on about 6 address checking sites (Vodafone, Telecom, Orcon, Snap, ...) and all showed VDSL as available. Also a line test about six months ago by Full Flavour Media indicated the line was suitable for VDSL (have no idea what test that was).

Our ADSL modem stats are:

ADSL Link........................................... Downstream .............. Upstream
Connection Speed ............................ 12786 kbps ................ 945 kbps
Line Attenuation ............................... 18.0 db ...................... 8.9 db
Noise Margin ..................................... 12.1 db ...................... 15.8 db

In another thread I see someone with Line Attenuation of 19db getting 30.5 Mb/s download speed.

Is the line attenuation figure different from a VDSL vs ADSL modem?

ie. does 18db from an ADSL modem rule out VDSL?

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#978150 31-Jan-2014 15:05

Hello... Our robot found some keywords in your post, so here is an automated reply with some important things to note regarding broadband speeds.

If you are posting regarding DSL speeds please check that

- you have reset your modem and router

- your PC (or other PCs in your LAN) is not downloading large files when you are testing

- you are not being throttled by your ISP due to going over the monthly cap

- your tests are always done on an ethernet connection to the router - do not use wireless for testing

- you read this topic and follow the instructions there.

Make sure you provide information for other users to help you. If you have not already done it, please EDIT your post and add this now:

- Your ISP and plan

- Type of connection (ADSL, ADSL2, VDSL)

- Your modem DSL stats (do not worry about posting Speedtest, we need sync rate, attenuation and noise margin)

- Your general location (or street)

- If you are rural or urban

- If you know your connection is to an exchange, cabinet or conklin

- If your connection is to a ULL or wholesale service

- If you have done an isolation test as per the link above

Most of the problems with speed are likely to be related to internal wiring issues. Read this discussion to find out more about this. Your ISP is not intentionally slowing you down today (unless you are on a managed plan). Also if this is the school holidays it's likely you will notice slower than usual speed due to more users online.

A master splitter is required for VDSL2 and in most cases will improve speeds on DSL connections. Regular disconnections can be a monitored alarm or a set top box trying to connect. If there's an alarm connected to your line even if you don't have an alarm contract it may still try to connect so it's worth checking.

I recommend you read these two blog posts:

- Is your premises phone wiring impacting your broadband performance? (very technical)

- Are you receiving a substandard ULL ADSL2+ connection from your ISP?

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Coil

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#978211 31-Jan-2014 16:15

Not gonna happen.

12DB cut off.

Line Attenuation ............................... 18.0 db

Check your wiring in the house. I am sure at 18DB your sync should be around 16Mbp/s

In another thread I see someone with Line Attenuation of 19db getting 30.5 Mb/s download speed.

You cant compare ADSL2 attenuation with VDSL2.

The more speed the more noise it makes and interference it makes. I get 50Mbp/s over 13DB with VDSL2. I had 2DB with ADSL. (Down stream figures)

DS248

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#978257 31-Jan-2014 17:04

(Since no way UFB will be available here any time soon, if ever - despite a main trunk fibre cable running passed the 'gate')

Thanks anyway.

Sideface

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#978258 31-Jan-2014 17:10

You had a lucky escape - the Chorus tech gave you good advice :)
I had similar ADSL specs to yours, but tried VDSL anyway.
Bad call.
Despite a text-book Chorus install (ie good house wiring), my VDSL performance was so bad that I had to go back to ADSL 10 days later.

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chevrolux

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#978262 31-Jan-2014 17:36

You have some sort of issue.

At 18dB you sync rate should be much much higher. I have 29dB and sync at 12Mbps. Also if pre-qual tests suggest you can get VDSL then you must be close enough.

First off eliminate house wiring issues by getting someone in to check it all out and install a splitter. Then if there is no change you can call your ISP and get them to send Chorus out - probably just request VDSL and Chorus will sort out line issues on the install day.

sbiddle

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#978265 31-Jan-2014 17:39

Attenuation reporting will vary between ADSL2+ and VDSL2 devices.

Using your modem figure is also pretty much worthless unless you have a master filter installed or the modem is connected directly to the demark. Internal wiring can dramatically affect the attenuation due to the bridge taps in your average premises with series wiring.

As mentioned above however you should be getting a higher sync rate with that attenuation. This indicates a probable internal wiring issue that can be eliminated with a master filter.

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eXDee

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#978336 31-Jan-2014 20:18

^This.

A friend had a 12 megabit sync but was sub 500m from the exchange, and still got it. Poor wiring results in a 25Mbps VDSL2 sync, but with a 10Mbps upload and a real world 3Mbps DL speed, its definitely worth it.

DS248

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#978373 31-Jan-2014 23:18

Thanks for the feedback.

One point I should mention, we do have a master splitter, albeit reasonably old (installed long before we bought the house two years ago).

The internal wiring is far from ideal though with at least one intermediate wire join between the splitter and modem. Unfortunately, we have a concrete slab ground floor & block walls on GL making it very difficult to upgrade the internal wiring without damaging wall linings etc. Don't even know where the cable runs from the splitter until it emerges from the wall in my office, but must be ~20m or possibly more in total.

The DL speed is not a big issue but faster would always be nice. Upload speed is the big annoyance. From the comments above it seems I do need to get the internal wiring up to scratch.

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#978402 1-Feb-2014 06:58

see: Forums > New Zealand Broadband > Hardware supplied with VDSL installation? - Questions for Chorus Technicians

"Chorus minimum standards / requirements for a VDSL install are:
900m max from the cabinet.
A master [VDSL] splitter installed at the ETP outside the house where the service lead meets the internal wiring
And if there isn't any existing cat5e or better a new piece must be run from the ETP to a dedicated RJ45 jack point"

Your old filter will be an ADSL one - you need a proper VDSL filter and new wiring (as above) - even then you may get a poor VDSL connection, given your distance from the cabinet.
So the Chorus tech probably gave you good advice.

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DS248

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#978460 1-Feb-2014 10:48

Any chance this type of technology being used in NZ? Seems to offer a reasonable extension of VDSL range.

http://www.bectechnologies.net/main/images/datasheets/vdsl2.pdf

According to this range up to 8000 ft (2.5 km) is possible. Does not look horrifically expensive?

There other similar options; eg. http://www.strowger.com/solutions/vdsl-loop-extender.html?
http://www.strowger.com/media/VDSL%20extender%20user%20guide%20VER-1P%EF%BC%88V1.1%29.pdf

sidefx

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#978484 1-Feb-2014 11:40

DS248: Any chance this type of technology being used in NZ? Seems to offer a reasonable extension of VDSL range.

I'm not sure it would really be worth it given the high percentage of people in range of cabinets and UFB rollout...?

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DS248

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#979250 3-Feb-2014 10:44

Alas there are large numbers of households out of VDSL range, including in urban areas.

webwat

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#982266 8-Feb-2014 13:41

You might need to look at putting some Cat5e cables through the ceiling and running it down the corner of walls and along the skirting like the old days.

Time to find a new industry!