Hub SN Margin tweaks

Currently using BT Hub 6.1.1.R with the following stats:-

Bandwidth (Up/Down) [kbps/kbps]: 448 / 3,424

Output Power (Up/Down) [dBm]: 11.5 / 18.0

Line Attenuation (Up/Down) [dB]: 30.0 / 53.0

SN Margin (Up/Down) [dB]: 23.0 / 5.0

Q1 I have downloaded DMT V7.30 is this the correct version for the Hub?

Q2 What username and password do I use to get it to connect?
I tried [email protected] and blank and it wouldn't work.

Q3 What is the default SN Margin and what should I change it to, to try to get a higher connection speed?

I have never tried this tweak before so any help would be much appreciated

I don't think the dmt thing works anymore.

I wouldn't use it to lower your margin anyway as it is already below target.

The best 'tweak' anyone can do at home is disconnecting extension wiring bellwire at the master.

My firmware hasn't upgraded to 6.2.2.6 so the DMT tool should still work. How do I log in?

I am already connected via the test socket. When my extension wiring was connected, my sync speed was only about 1000 Kbps.

username admin

password admin

The address is 192.168.1.254

use port 23.

Version 7.3 of DMT tool works with 6.1.1.R.

You'll need to go into "Special" (top menu tabs)

Misc. Settings.

And click to enable the following;

show extended information.
unlock experimental are (modemoptions/last tab).

However, Randomjointer is right about your downstream snr - it does seem rather low. I aim for an snr of 9 to 10.

If your sync speed improved so much by going to the master socket you could always think about cutting the ring wire and putting your router back where it suited you to have it (if that matters).

Good luck

Martin

First tweak I would suggest is to change BT filter to something more reliable. I use ADSL Nation filter and have same SNR as yours but connection rate 3900k on BT box and 4800k on Zyxel. The filter gives me about 400k increase.

HTH.

Just read the last part of your original post.

To change the snr, (after you have done all the stuff above...)

Click the connect button (dmt will make some great noises then connect to the hub).

Look at the info adjacent to "Downstream," in particular the SNRM value.

Before I tweak mine normally says about 15. If your is 10 or less, you should really stop there.

Going down to 8 or less will likely mean an unstable connection. Indeed, I understand some people have used this tool to *increase* the snr to improve stability.

Let's suppose your value is above 10.

Click on the tab to the right "modemoptions"

I have found using the slider to be a pain, so...

Under the table on the right there is an "modify" button. Enable it.

You should click on the value for 00, which is currently at 00. Change it to 08.

Click on "Apply/ resync."

You should end up with a snr of around 9 to 10 and a faster sync rate if your snr was higher previously.

Good luck. Let us know how you get on.

Martin

Although, if the OP has an snr of 5 and no bellwire, he is probably not going to improve speeds with dmt tweaking without losing reliability. IMHO.

Edited by deleted (Sat 06-Jan-07 20:09:10)

"Before I tweak mine normally says about 15. If your is 10 or less, you should really stop there."

Thanks for the info, I can now connect with the DMT.

My SN margin is normally 4.5 - 6.5 when I sync at about 3.5 Mbps and does not normally disconnect. ( It did during a thunderstorm the other night and my IP dropped to 1000K and I had to wait for 3 days to come back to 3000K.) I am about 3km from the exchange.

I have only ever seen the margin above 10 when I have a poor sync of about 1500K. I understand that Max SDL will tolerate much lower margins than fixed speed.

I have tried connecting the Hub with the extension wiring with ring wires 3&4 disconnected and the SN margin was only 2.5.

I have found the Hubs to be temperamental with extension wiring which does not bother my Linksys router at all. I therefore connect the Hub into the test socket for the moment to keep my speeds up.

Is there any documentation/help available for using the DMT tool?

I just saw your other post.

What was your initial and final SN margin when you went from 3.5 to 5.15Mb and how far are you from the exchange?