SYNC Speed dropping?

[tinribs]

Product SYNC speed IP profile Interleaving Profile changed
Max 7392 6500 Auto 15/04/2008 20:22
Max 7392 6500 Auto 15/04/2008 20:25
Max 7968 7000 Off 29/05/2008 09:43
Max 6816 6000 Off 29/05/2008 15:13
Max 6240 5500 Off 18/06/2008 14:05

I know this may be needle in haystack time but does anyone know why by sync speed should be decreasing like this? :(

Thanks

T

[tboorman]

Have you tried connecting your ADSL router/modem to the test socket at the back of the master socket using a new filter?

[tinribs]

Not yet as its a pain as I have to move lots of furniture etc around to get at everything. Is the normal cause of this sort of thing internal then I guess? Just don't understand why my profile went up and is now on its way down........same set up? Weird.

[tboorman]

You need to do this to eliminate your internal wiring being the cause of the problem.

[smartybones]

all sorts of things can affect your sync speeds.....

some of them can be completely out of your control or even BT's control.

I did hear of one case where a junctionbox on the top of a pole, in the summer gets enough direct sunlight to warm the thing up enough where the metal expantion comes into play. the connection is not as tight as it should be, which will increse the attenuation of the line.

can you imagine how hard that would be to actually find?

noise can be introduced almost anywhere along the line. some bloke down the road somewhere may have had a wind turbine installed to cut his electricity costs. the generator may be giving off a little RF interferance which will add a little noise.....

the thing is, there is very little can be done about this and BT wil only investigate it if your sync speed had dropped by more than 75% (i think its 75%, it may be 25%, but i am sure someone will correct me) of your original sync speed after the first training period....

check your logs, see when the sync speeds have changed, match them up to any alterations in snr changes... and than work out what has changed since the problem started......

it may also be somthing as daft as a filter going toes up.!

[tinribs]

Thanks Smartybones and tboorman. Tried my master and router connected at 6976/448 with noise margin: up 27 down 13 and attenuation at 23 up and 21 down.

Went back to 'normal' set up and connected at 6784/448 with noise margin: up 24 down 15 and attenuation at 23 up and 21 down. So, trying to sound like I know what I am talking about, there does seem to be loss at some point? But not too much?

In truth I have no idea if that's good or bad if it makes a significant difference or not? Thanks again.

[tboorman]

You need to leave your router connected to the test socket for a few days to see whether it improves stability or not.

It also looks like your target SNR margin has been increased from the default of 6 dB to 15 dB at some point, and this will have caused a reduction in sync speed.

[tinribs]

Thanks again for your time.

So, how do I go about decreasing the margin back to 6dB? Would it help to turn interleaving back on? Would that have made the difference?

T

[tboorman]

DLM is supposed to automatically reduce the target SNR margin in 3 dB steps if the line is stable for 14 days - unfortunately this does not happen in many cases.

Turning interleaving on can improve the stability of a line.