DMT Tool, bins and bits/bin - what are the best settings to use?

dirtydog · 24 Jul 2007 at 08:32

Can someone suggest the optimum settings for the items I have circled?

I have read a technical explanation here: http://en.wikipedia.org/wiki/G.DMT but what I am after is a layman's terms, words of one syllable answer as far as it is relevant to the end user.

I have a long line and I used to be able to squeeze 2Mb speeds out of it (= sync at 2272). For the last month or two I have not been able to stay synced at that speed 24/7 like I used to. I have not changed any settings in DMT or anywhere else. The best I can manage now is to stay at a 1500 profile (= sync at 1728) 24/7.

What I would like to know is the optimum settings to use for those items I have circled in red. I know they must have a big effect on performance because I have experimented with various settings. (For example, lowering the 'max bits/bin' setting lowers my sync speed, but it isn't a simple case of putting it up to 14 or 15 either because above a certain figure it seems to have no effect or to make the line less reliable.) I have also tried using the 'auto' settings for 'bin adjust'.

I know that there is a new bras profile of 1750 being introduced at the end of the month, which requires a sync speed of 2016. At the moment I cannot even reliably stay synced at that speed 24/7, but I used to be able to stay at 2272 24/7 no problems. I feel that tweaking the settings I have highlighted is the answer but I cannot work out what the best settings are.

Does anyone know? :eek:

Thanks in advance

tolien · 24 Jul 2007 at 12:51

You're as well leaving them be - there isn't a "best" setting, just what works for your line.

Reducing the bin ranges means you need more bits per bin to get the same rate, and vice versa.

A graph of bits per bin for each bin might be useful, though if you can reduce the target SNR margin you'd easily make 2Mbps given you're synching at 16.5dB...

dirtydog · 24 Jul 2007 at 13:27

I can sync at 2Mb easily...

But it can't hang onto that in the evening, in fact it's been having trouble hanging on to 2016kbps even. The SNR margin drops to as low as 8-10 which isn't enough, even when I had interleaving on it wasn't enough.

I have the router connected directly to the test socket with no filter or telephone attached (doing that gives me a slightly higher line attenuation) so that is ruled out of the equation. I have tried a number of different RJ11 leads and they are all short ones for what that's worth.

Tweaking the bin settings seems to be the only other option.

Sone · 24 Jul 2007 at 22:30

dirtydog said:
But it can't hang onto that in the evening, in fact it's been having trouble hanging on to 2016kbps even. The SNR margin drops to as low as 8-10 which isn't enough, even when I had interleaving on it wasn't enough.

my SNR is currently @ 7.5 an i have been synced for 34 days (thomson 546)

Locky · 24 Jul 2007 at 23:21

which version of DMT tool is that?

dirtydog · 25 Jul 2007 at 08:06

2.20, for the Voyager 205 (aka Solwise SAR110). If it looks different to other versions of DMT tool that you may have seen before, it's because the program is tailored to fit the options that each particular router offers.

I think as tolien says, I need to get the target SNR margin reduced, so I'm hoping that if I stay connected at 1728 for 14 days or so with few errors (which should be the case), it will automatically trigger it to be lowered.

eracer2006 · 25 Jul 2007 at 15:48

mines been wierd too was syncing at 5.5mb stable now only 4mbit

dirtydog · 25 Jul 2007 at 17:25

How on earth do you get such a high sync with such a high line attenuation :eek:

I didn't think that was possible.

What router is that?

dirtydog · 26 Jul 2007 at 07:47

Are this amount of errors sufficiently low that I can expect an automatic lowering of the target SNR margin if it stays like this for a few weeks?