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[richi]

I'm still on ADSL2+ because the cabinet is very close to the exchange (the E-side must be less than 50 m).

I'm wondering whether I'd get better sync speeds if I switched to VDSL2. I've seen some "conflicting" graphs

Expert opinions? Cab is a Huawei. Stats below:

                        Down    Up
SNR Margin (dB)         3.0    6.8
Attenuation (dB)       34.0   21.7
Output Power (dBm)     18.9   12.1
Attainable Rate (Kbps) 17836  1088
Rate (Kbps)            17251  1142
(profile is interleaved, with 6 dB target, but downstream is Broadcom-tweaked to 3 dB due to low-noise line)

Thanks in advance...

[licquorice]

What does the checker estimate? https://www.dslchecker.bt.com/

[richi]

What does the checker estimate? https://www.dslchecker.bt.com/

Garbage data: It estimates 6 Mbps for ADSL2+ and 2 Mbps for VDSL2!

But I can order FTTPoD for £39,000... which is nice.

[richi]

Perhaps this is useful. Here's the tail end of an adsl info --Bits command:
Tone number      Bit Allocation
   490          3
   491          3
   492          2
   493          3
   494          3
   495          2
   496          2
   497          0
   498          3
   499          0
   500          2
   501          2
   502          0
   503          0
   504          0
   505          0
   506          0
   507          0
   508          0
   509          0
   510          0
   511          0

[kitz]

With an atten of 34dB, then your line length is going to be ~2.5km from the exchange.
If the cab is only 50m from the exchange then that leaves you with a D-side of 2km at best... which is at the point when VDSL doesnt perform so good.

VDSL2 uses higher frequencies, but it looks like you're not going to be able to make much use of them.  Add on the fact that VDSL tones in the ADSL range have PSD masks applied then bit load in the same tones will likely be less than on adsl.

Also you'd be unlikely to tweak your SNRM down to 3dB on FTTC, so you are unfortunately in a situation whereby your speeds would be less on VDSL than ADSL2+

[richi]

Thanks Ms. K. I agree it's probably 2.5 km, given what an OR engineer told me about the route. It's just that my stable ADSL2+ speed seems way higher than I've got a right to expect with that much copper.

I'd forgotten about the PSD mask though, which rather puts the tin hat on it. Thanks again.

[Icaraa]

Thanks Ms. K. I agree it's probably 2.5 km, given what an OR engineer told me about the route. It's just that my stable ADSL2+ speed seems way higher than I've got a right to expect with that much copper.

I'd forgotten about the PSD mask though, which rather puts the tin hat on it. Thanks again.

I agree actually. How are you getting 17Mb at 2km?

[richi]

I agree actually. How are you getting 17Mb at 2km?

In fact it's at least 2.5 Km (probably closer to 3 Km, looking at the map again).

There's no obvious simple answer to your question, but here are some thoughts:

• The route has no obvious sources of REIN/SHINE/RFI
• The final 500 m is recently replaced, good-gauge overhead cable
• The rest is underground
• I'm told it's in extremely accurate balance -- due to a misdiagnosed tie-pair fault, the entire D- and E-side has been worked over with a fine-toothed comb by countless OR staff, sent out again and again by the tireless Pulse8 (TTB reseller)
• I have the new tool-free NTE with the mk.4 filter
• 3 dB target margin, but 7 ms of interleave
• Not error free, but I'm content with a few ES per day and the occasional SES
• Billion 7800NXL