Best 15 quid

Just thought I share my experience as I'm well chuffed.

I was running an old DSL-504. Working ok and had been for years but the other day I put my phone number into a site and it said I should get 7M which I wasn't. So I risked 15 quid on a TP-Link TD-8840T to replace the DSL-504. Sync speed on DSL-504 was 6624 Kbps, IP Profile 5500 kbps. On 8840T sync is 7616 kpbs and after a week my IP profile is now 6500 kbps. On speedtest.net the best I used to get was 5.05M, today I got 6.20M. That's 23% faster for 15 quid .

I've also asked my ISP to turn off interleaving to see if I can get 8128 and thus a higher profile still. The exchange in not ADSL2 so until (or if) that happens that as best as I can do.

That's good. It's a bit of a lottery though, it could have produced a lower sync.

Perhaps your new router has the same chipset manufacturer as the exchange end, that is quite often believed to give better results.

I was expecting the same with a small chance of bit better. I don't think it is down to chip set. I reckon it's down to the age of the DSL-504 because:

1. Some components have deteriorated with age (such electrolytic caps)
and/or
2. Firmware/hardware has improved (so its now faster/smarter)

I'm inclined to think it is both. The DSL-504 never connected as fast even when new and looking back there has been a small deterioration over the last few years. Processing power has certainly improved over the years so faster/better hardware seems a reasonable theory and electrolytic caps do deteriorate with age.

When I was checking out the TP-Link adsl router I came across a post but someone who had replaced a DSL-504 too and he also got a speed increase.

I have seen reports on other forums of the TP-LINK giving intermittent connections.

In reply to a post by john2007:

Perhaps your new router has the same chipset manufacturer as the exchange end, that is quite often believed to give better results.

That's not what I see. My exchange end is TI but using a TI chipset router is no good for me, a Broadcom chipset works much better.

I think line length/quality is a big factor on what chipset will be best for your line

In reply to a post by b4dger:

In reply to a post by john2007:

Perhaps your new router has the same chipset manufacturer as the exchange end, that is quite often believed to give better results.

That's not what I see. My exchange end is TI but using a TI chipset router is no good for me, a Broadcom chipset works much better.

You mean the TI-AR7?

Mine seems rock solid. I'm running RouterStats-Lite to record its stats. It's the only one I could find that works with TP-Link. The stats are a bit minimal in the router interface. No graph like the DSL-504 had.

The numbers before and after are odd. DSL-504 interface said Atten = 18dB, SNR=3dB, Sync 6624. The 8840T has atten = 24, SNRM = 8, sync 7616. Graphing SNRM it ranges from 6-9 with the odd dip down to 5. The DSL-504 said I had less attenuation before but it connected slower which contradicts that.

In reply to a post by bearded_malc:

The DSL-504 said I had less attenuation before but it connected slower which contradicts that.

No, it makes sense- you're reversing cause and effect.

The modem connects at rate determined largely by the SNRM and then measures the attenuation- lower speeds give lower attenuation (ignoring differences due to different ways of measuring it).

Edited by billford (Sat 11-Jun-11 10:09:32)

I see what you're getting at and that fits with my experience but it contradicts:

http://www.kitz.co.uk/adsl/max_speed_calc.php

In that calculator the lower the atten figure the faster it goes.

In reply to a post by bearded_malc:

In that calculator the lower the atten figure the faster it goes.

True, but:

The figures used are based on attenuation measured at 300Khz for adsl1
.
.
The calculator is based on a default Target SNR of 6dB

In essence it's just saying that the longer your line is (ie the higher the attenuation) the slower your maximum speed will be and giving a guide, but it's not a simple calculation because the actual attenuation varies with the speed rather than being the value for the fixed 300kHz that Kitz uses.

If the target SNRM were increased, the speed would go down and so would the actual attenuation.

The attenuation as reported by the router isn't really a single figure, it's a sort of average over the frequency range being used and can only be measured after that frequency range has been determined ie when the sync has been determined by the SNR.

There are several inter-dependent variables involved, which makes it a pig of a non-linear calculation to get right!

Edited by billford (Sat 11-Jun-11 10:25:54)