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My last words on the subject, lol 
SNR
1. Signal-to-noise ratio is an engineering term for the power ratio between a signal (meaningful information) and the background noise.
2. When your modem attempts to negotiate ADSL it looks at the line and basically sees attenuation and noise put together. Attenuation gradually increases as frequency increases and noise is a random pattern of low level interference in the background.It's very similar to a conversation at a party and it's dealt with in the same way; we naturally account for both distance from the other person and the amount of background noise. When we do we don't just talk loud enough to be heard, we speak a bit louder waiting for the idiot with the stupid, loud laugh to start up again. We add a bit extra on to make sure we're louder than the average change in background noise. This is a SNR margin.
ST516v6
3. The SpeedTouch 5x6 products are ADSL2+ replacements for the SpeedTouch 510E, 536 and 510 switch models.
The 516v6 uses the Broadcom chipset, BCM6338 which is the cheaper, more integrated version of the BCM6348.
DMT Modem Tool
4. A nice bit of software (from Germany) that allows you to tweak and monitor certain models of Speedtouch routers (516 536 546 585 608 706 716 780).
Although this software is in German it can be switched to English via 'Extras>weitere Einstellungen' (Special>Misc. Options) and then initiating a program restart OR it will automatically switch to English if it detects a Annex A connection.
How do I use DMT Tool?
Use this picture as a reference
A. Fill in your login details and click Connect.
B. Click the modemoptions tab.
C. Untick default.
D. Tick modify.
E. Enter a value into option 00.
F. Click apply/resync, wait for the new sync and click save settings if you are happy with the result.
G. Click Refresh to confirm settings or check if telnet session is still active.
How does it work and what settings should I use?
Changing the value in modemoption00 increases or decreases the gain on the SNR margin across all the tones in the frequency range. Think of it as a volume control.
The settings you should use are highly dependant on your own line conditions and can only be determined through experimentation, however as a rough guide this is what I have discovered for my own situation:
Line length: 4.5Km
SNR Margin in DSLAM: 15db
Router Signal Attenutation: 46-49db
value* - margin
08 - 10db
10 - 10.5db
18 - 11db
20 - 11.5db
28 - 12db
30 - 12.5db
38 - 13db
40 - 13.5db
48 - 14db
50 - 14.5db
58 - 15db
60 - 15.5db
68 - 16db
70 - 16.5db
78 - 17db
80 - 17.5db
* - hexadecimal.
Why should I tweak?
Simple, to find the best performance vs stability level for your ADSL(MAX) line. Please note you must be realistic about the capabilities of your line. If you try and push the limits too far, your sync will fail when the line is exposed to large amounts of noise or interference, especially at nightime.
Example
I've made a small movie showing clearly the effects of tweaking the SNR margin and it's impact on high frequencies and tone bit loading.
Watch it here
You can download the DMT screenshots used in the movie from here.
Good luck and happy tweaking
Links to sources
1. Wikipedia
2. Whirpool
3. Speedtouch
4. DMT tool
I use firmware R6.1.0.5 on my router, you can get this here.
Jinx.
Edited by JinxterX2 (Mon 22-May-06 16:06:32)
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Result
Rock solid 5600Kbps connection @ 15db
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The latest DMT tool v7.09, just out of beta, now does SNR fluctuation per tone monitoring
Screenshot
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Register (or login) on our website and you will not see this ad.
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Interesting - I wonder if it handles bitswapping properly.
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That DMT tool is excellent even for us old 510v4 users as the auto monitor now handles 1 decimal place.
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
Check my bad boy speeds out on ZeN
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OMG I forgot to mention..big thanks to humm for first writing about DMT tool in the forum, ta
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Nice controlled margin drop during peak noise period, connection holding steady
Graph
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what does that slider do ? is it an alternative to putting numbers in the boxes ?
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Yes it is but you have no idea what number you're putting in if you use that slider, until you have done a resync, so it's useless really.
Edited by JinxterX2 (Tue 23-May-06 00:08:58)
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15+ hours uptime and 5600Kbps sync still going strong, this is pretty much at the limits of what my line is capable of, average SNR margin over the whole time period so far is 13db, not bad considering the target is 15db. Damn, just 100kbits short on my sync rate to qualify for a 5mbit Data Rate...hmmm..bit of fine tuning required I reckon 
This graph pretty much says it all
Lowest margin: 8.5db
Edited by JinxterX2 (Tue 23-May-06 05:44:34)
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If I wanted my SNR to go down to about 3 dB, what number should I try to start with?
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If your target SNR margin in the DSLAM is set above 9db you're unlikely to get down to 3db with tweaking and even if you did, you're not leaving any room for dealing with nightime noise. Like I said in my first post, I can't tell you what value to use, experimentation and testing is needed based on what you already know about your line conditions.
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My default target as set by BT is 6, to get onto the next IP data rate I've lowered this to 3 using my Belkin 7633, I've a long but very quiet line, SNR never varies more than 1 dB regardless of time of day. I've bought a speedtouch 536 on Ebay (
Edited by 7cfm (Tue 23-May-06 15:44:30)
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Got my 536 today. I can see why it was on DSL Depot cheap - its semi faulty! Half the time the power flashes red/green and it doesn't work :|
Anyway, have it working now, first hop pings are 4-5ms higher than the 7633 but it is a few 100 kbs better off in sync. DMT tool is pretty neat! Seems so far to be holding 6db solid but I'm not sure how many decimal places it goes to? The belkin would show 6.1,5.9 etc, this has shown nothing but 6db in 4 hours...?
EDIT: Soon as I reply it drops to 5.5db!
How do you do that SNR graph? I cannot see how to turn snmp on?
Edited by deleted (Tue 23-May-06 16:03:00)
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There should be a 30 day warranty from DSL Depot, if it's faulty, send it back. I use ADSL Monitor to make SNR graphs and sometimes use the CSV output from that in M$ Excel.
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In reply to:
SNR never varies more than 1 dB regardless of time of day
lucky sod
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Same here goes from 5.5 to 6.5 *whistles*
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
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Yeh, isn't he, half!
Oops, it's 5.11pm and my router's just started disconnecting. Looks like that's me off the air until tomorrow.
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Thanks.
Did you have any issue with the V6 firmware? When I do it on mine I let it reset to default config but now it doesn't have a profile for UK Broadband (I can only choose routed PPP or bridged)
I could do it myself but there are no options in the web config - I'm guessing its a telnet job?
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Use the Setup Wizard, select Routed PPP, then you can pick 0.38 as your VPI/VCI from a drop down menu, and below that choose PPP over ATM...sorted
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Yeah I'd managed that part but it didn't seem to be doing NAT!
I went back to 5.x and then forward to 6 again and now it works fine?!
I can report your SNR/Modem Option table seems to be correct.
For eg. I have a 6db Noise margin profile and using modem option 40 gives me 4.5db = -1.5db
As for the 536 vs Belkin 7633 I can report there is pretty much nothing in it so far, although it appears the Speedtouch is producing less errors. Sync speeds vary a little but they are +- 3% of each other at default settings.
If this will hold onto 4.5db where the Belkin couldn't, I'll be up another 512k profile step!
Thanks for the effort by the way, appreciated
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DMT 7.11 now with sound effects.
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
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I think because it's not a proper UK version of the firmware it might have a few issues, nothing that bothers me tho.
Edited by JinxterX2 (Tue 23-May-06 21:31:12)
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Cool
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In reply to:
If this will hold onto 4.5db where the Belkin couldn't, I'll be up another 512k profile step!
You want to monitor SNR fluctuation per tone in DMT, if there's too much negative flux across many tones (especially the mid-range to high) you know your sync rate is too high and will most likely fail. That's what I've found on my line anyway.
Don't be too ambitious on your SNR targets to start off with.
Edited by JinxterX2 (Tue 23-May-06 22:09:16)
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I've already done most of the messing with my Belkin 7633 and this proves to be pretty much the same beast.
I can run a low of about 5db at night, which equates to about 7db in the day. I tried lower but it looks like the 536 cannot hang on either during the late night noise period.
Just lost about 1db instantly, so I switched back to the Belkin and that was down 1db too. Very similar performance!
Have to decide which one to keep now, I like DMT tool but the Belkin has a much much faster web interface (plain html vs some cgi on the Speedtouch)
I should not be greedy, I see you have to run a much higher SNR to keep it stable which is a pity 
I've had two weeks uptime at 5-7db on the Belkin, so my line is not too bad I guess (57db Att - 4500-4700kbps)
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Well it seems my max sync stable rate is 5600Kbps, any higher (even 256kbits more) and it craps out during the noise period, which is a pity because it means I can't get the Data Rate I wanted (5696Kbps).
The SNR per tone fluctuation readings in DMT are really interesting when you try different values for modemoption00, great program
Doesn't the Belkin 7633 use the BCM6348 chipset? If so it's not suprising it performs similar to the Speedtouch.
Edited by JinxterX2 (Wed 24-May-06 04:58:43)
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Bit of messing about with the values (and lots of retrains at various times of day/night  ) has yielded a sync of 5696Kbps using modemoption00=5d, which will hopefully keep the target aimed at between 15-15.5db (during the day) and 8-13db (during the night). If it holds the line I should get the 5120Kbps Data Rate at some point (got the figure wrong in my last post, oops). Those gainQ2 red dots in DMT graphs look intriguing...
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i can report the DMT tool works for the speedtouch 580 aswell
PIPEX-1Mbs
ROUTER:-Speedtouch 580i firmware R 4.3.2.6.0
Auth:-59dB Down 31 Up
SNR:-19dB Down 19 Up
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DMT v7.12 out
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Hi,
Great program working well on my connection with a ST585.
Only gained about half a meg on my sync speed, profile is stuck at 2meg on the BRAS though...at least for now anyway.
When I "save settings" is this stored in the router or do I need to run the program whenever the router is rebooted?
TIA
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In reply to:
When I "save settings" is this stored in the router or do I need to run the program whenever the router is rebooted?
Not unless you reset to factory defaults.
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Ok, thanks
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I
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What was your attenuation before the 536? SNR margin of 2.5db isn't good, I'd be suprised if you didn't lose sync before 11pm.
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SNR was about 56 on the 7633 but more importantly the snr was about 3 and hardly fluctuated. I'll check the logs in the morning and report back but I'm quietly confident that everything will be OK.
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Well, its 23:15 and I'm still here, SNR rock solid at 2.5 dB
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Everything fine overnight, snr still steady at 2.5 dB. I've had just over 2000 CRC errors, about a 1000 HEC errors and about 1600 errored seconds in 12 hours. The connection seems stable purely from a usage point of view, I've just downloaded 100 Mb of a Linux ISO and IE is reporting a transfer rate of 417 KB/sec (my IP rate will still be 3.5 Mbps until Monday night)
All in all looks OK
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Nice one My SNR margin stability has improved since moving the router as far away from the pc and monitor as possible modemoption00=60 is giving me rock solid syncs between 5600-5800Kbps and 14.5-16db margin during the day with 8.5-12db at night, but still with thousands of CRC and HEC errors, however they don't appear to affect anything so I'm not too worried about them, being on a non Interleaved, noisy line. Average download speed (non Peak time) is 550K/sec.
Edited by JinxterX2 (Sat 27-May-06 06:47:27)
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Any idea what the options "power cut back" and "trellis coding modulation" mean? I've got them both ticked at the moment.
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http://en.wikipedia.org/wiki/Trellis_coded_modulation
The power cut back option doesn't do anything as far as I know.
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Oh DMT v7.13 is out btw
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I'm still not sure why you would want to switch trellis off, trawling through the forums, most people who post their router stats seem have it switched on, although I've seen a couple with it off. It therefore appears to be better to leave it on, why you would want it switched off is a bit of a mystery.
I wondered if power cut back might be something to do with allowing the router to reduce the power output, therefore if its unticked it will be permanently be at full signal output - I couldn't think of anything else it might be.
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Thats the 4th one in 6 days
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Just discovered if I sync with a 13db margin I get a hugely reduced CRC/HEC error rate, any margin above or below that sends the errors shooting up again, wonder if this means there is a SNR 'sweet spot' for every line? Or maybe it's just a random event, dunno.
Update: bah, was a random event methinks..CRC errors back in force as usual
Edited by JinxterX2 (Sun 28-May-06 17:40:46)
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DMT Modem Tool v7.14 is out
DMT v7.14
added: ability to visualize BITSWAPPING during SNR monitoring/observation
fixed: Bug in SNR monitoring (SNR-tones without bits were measured/included in measurement)
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Ta...
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
Check my bad boy speeds out on ZeN
Sign up for Latency Monitoring
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Are you using it on your 510v4 banger?
Might just have to dust mine down if you are haha.
------------------------------------------------
PIPEX
(Xtreme5)
Pipex GO! 2Mb(NDO Speed Test)/(Adsl Guide Speed Test)
Can'tWait4MaxDSL!!
Local Line Atten(dB): 46 Local SNR Margin(dB): 22
------------------------------------------------
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I am indeed, the auto SNR monitor is particularly useful
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
Check my bad boy speeds out on ZeN
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How does it perfrom banger?
I lose about 4-5db SNR if I drop from my DG834PN to ST510v4............which leaves it at about 18db.
Is it worth me upgrading to the 3.x.x. software or can I leave it at 2.7?
I'm running DMT Tool 7.14 and it won't draw the graphs for SNR Noise & Bit Loading Values:(
Where can I get 7.09 from?
------------------------------------------------
PIPEX
(Xtreme5)
Pipex GO! 2Mb(NDO Speed Test)/(Adsl Guide Speed Test)
Can'tWait4MaxDSL!!
Local Line Atten(dB): 46 Local SNR Margin(dB): 22
------------------------------------------------
Edited by wolvesmad (Wed 31-May-06 09:40:57)
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Thanks!:)
Ok, I've just run 7.09 and it won't display the graphs for my ST510v4!
Is it because it's not a 516 or somethin?
Just thought the graphs would be interestin to check for outside noise etc.
------------------------------------------------
PIPEX
(Xtreme5)
Pipex GO! 2Mb(NDO Speed Test)/(Adsl Guide Speed Test)
Can'tWait4MaxDSL!!
Local Line Atten(dB): 46 Local SNR Margin(dB): 22
------------------------------------------------
Edited by wolvesmad (Wed 31-May-06 09:58:11)
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I can't the graphs to show on 7.09 or 7.11..............Is it because I have the 510v4 or have I not clicked on something?
Thanks
------------------------------------------------
PIPEX
(Xtreme5)
Pipex GO! 2Mb(NDO Speed Test)/(Adsl Guide Speed Test)
Can'tWait4MaxDSL!!
Local Line Atten(dB): 46 Local SNR Margin(dB): 22
------------------------------------------------
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It performs ok. I did try a voyager 2110 which had SNR of 10 db on my Max line, the 510 sits at 5.5-6 db. DMT can't show the graphs for the 510 because of the chipset type.
I have heard that the 4.2 firmware gives a 3 db higher SNR and doesnt suffer the high first hop in traceroutes.
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
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Is the 510v4 as bullet proof on max as it is on fixed line services??
If my SNR on a 2Mb service is 20db during the day.................what could I achieve by tweaking?
7Mb? Also what about night time, when it's about 17db?
------------------------------------------------
PIPEX
(Xtreme5)
Pipex GO! 2Mb(NDO Speed Test)/(Adsl Guide Speed Test)
Can'tWait4MaxDSL!!
Local Line Atten(dB): 46 Local SNR Margin(dB): 22
------------------------------------------------
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Thanks to the instructions all working well but how do I stop DMT timing out
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Check the Misc. Options.
New DMT Modem Tool is out
DMT v7.15
added: latency/delay-info in ms (for fast or interleaved path/channel)
added: ability to activate experimental area (last tab)
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Wolvesmad you may have trouble with the 510 at those SNR rates. When I was on 2 Meg I had a steady 28 db night and day, and on max it has dropped to 6 db. Rock solid for me but I think you will have to suck it and see.
Tim
Eclipse now ZeN
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Edited by Banger (Thu 01-Jun-06 17:02:24)
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Already did and couldn't see anything there.
Only thing which may affect it is Send Keep Alive Signal - set at 95 secs
Problem is with the router - telnet timeout is set to 120 secs.
Have changed the Keep Alive Signal to 60 secs - lets see if that fixes it.
Edited by deleted (Thu 01-Jun-06 17:12:48)
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Telnet into the router and type:
env set var=SESSIONTIMEOUT value=0
saveall
Edited by JinxterX2 (Thu 01-Jun-06 17:30:24)
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Thanks.
Problem solved.
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Example #2
Take a look at the results from 3 consecutive days of testing. Sample period was 13hrs, router was tweaked and rebooted before each session.
Graph
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Thats really impressive but a little help please.
I am trying to set up my speedtouch 546 to get data from ADSLMonitor but I can't find out which commands to put into the telnet interface.
I have tried using the Speedtouch CLI Reference Guide but I'm afraid I'm none the wiser
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Whats your attenuation banger?
Your only getting 6.5Mb on a line that had 28db SNR @ 2Mb :S
------------------------------------------------
PIPEX
(Xtreme5)
Pipex GO! 2Mb(NDO Speed Test)/(Adsl Guide Speed Test)
Can'tWait4MaxDSL!!
Local Line Atten(dB): 46 Local SNR Margin(dB): 22
------------------------------------------------
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Put ADSL Monitor into a folder, then drop these 2 files into it:
configuration.cfg
dataconfiguration.cfg
This config is setup for the default user/pass (Administrator/blank) and a 30 sec sampling interval (don't raise this, only lower it, bug in the program). You might still have to do some cfg editing as some firmware versions have a different CLI prompt format.
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Thanks,
Data now being recorded to the csv file - just what I need
Edited by deleted (Fri 02-Jun-06 17:47:41)
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Attenuation is 24 db with a steady 8128 sync for 25 days now (after rebooting the router). Why I only get a max download of 6.5 meg is anyones guess, I suspect a stuck BRAS, but who knows.
Be interesting to see what sort of performance you get out of your 510.
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
Check my bad boy speeds out on ZeN
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Try decreasing the interval from 30000 to 5000... the program is a bit flakey, sometimes you have to restart it.
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Thanks,
I thought I had editted the post earlier.
Not really bothered about the graph as using Excel to graph the csv fole is much more useful.
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Yup the CSV output is very handy for Excel I'd like to produce more flashy looking graphs tho, Excel seems a bit primitive in that department...
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I understand now...........I'm aiming for 6Mb, but 5Mb is realistic tbh. Hopefully 6Mb can be achieved with tweaking.
What is the 510 like on low SNR??
------------------------------------------------
PIPEX
(Xtreme5)
Pipex GO! 2Mb(NDO Speed Test)/(Adsl Guide Speed Test)
Can'tWait4MaxDSL!!
Local Line Atten(dB): 46 Local SNR Margin(dB): 22
------------------------------------------------
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In reply to:
What is the 510 like on low SNR??
Hope someone else can advise on that as mine sticks at 5.5 to 6 db and is rock solid, havent experienced any lower than those figures.
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
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I got rid of my ST510v4 soon after upgrading to Max as it was not particularly good at holding sync on my longish line at the higher speeds. As it does not allow SNR margin tweaking, there wasn't much I could do to improve the situation other than swap it for something else.
Now running a ST510v6, which is a completely different beast and much better for Max.
Adam.
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In reply to:
DMT 7.11 now with sound effects.
I thought I was going mad! Strange noises every minute! I really need to get my server back up and running again so I don't have to run DMT on my Windows desktop.
Edited by deleted (Sun 04-Jun-06 09:49:48)
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You can turn them off in the Misc/Options.
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
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DMT v7.16 is out
fixed: Telnet-Session Keep-Alive did not work correctly
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DMT Tool v7.17 is out
added: DMT-Server update (v0.74)
fixed: SNR-Monitor results disappear after Automat-Task was executed (if activated)
Btw, modemoption00=TrainingMarginGain and modemoption01=ShowtimeMarginGain apparently, so probably best to experiment with both these options at the same time when tweaking.
Still not sure exactly what the Area51 registers do (options 0d & 0e) but they have an effect on sync rate anyway dunno about power levels.
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Just got a Speedtouch 536v6 and downloaded DMT V7.17.
DMT connects fine, show line speeds, errors etc. and will resync and reset the router.
However I cannot seem to change the sync. speed.
I set the Modem00 value to 28 then 80 - no change.
I then set the marging to max. on the slider - again no change.
I now don't know if the valuse aren't being set or if I have so much margin on SNR that it doesn't make any difference.
Just to confirm; setting the margin to maximum should bring the sync. speed down if there is a poor SNR?
I am right back to the test socket and the line is still going up dand down like a yoyo.
I have switched back to the Belkin with a sync speed of 5Mb but this also seems to be dropping the link every few minutes.
With the Belkin, the PPPoA seems to drop but the ADSL sync stays up.
However the router does not attempt to restart the line.
With the Speedtouch the DSL drops as well but the line does come back up.
I would like to be able to wind the sync. down on the Speedtouch to see if this will make the line more stable, but no joy so far.
It has 5.4.0.13 firmware; the download from the speedtouch website is just labelled 5.4 so I am wary of loading this over my router at present.
Not having a good day.
[Now back on the Speedtouch again - line is getting worse all the time]
Dave R
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"Btw, modemoption00=TrainingMarginGain and modemoption01=ShowtimeMarginGain apparently, so probably best to experiment with both these options at the same time when tweaking. "
From my testing so far this looks like the values you have to achieve before syncing.
I have 00 set to 80 and the link comes up at 8Mb
I have increased the 01 setting and found that with it set to 78 the link will come up at 8Mb but with it set to 80 the link will not come up at all.
My tentative conclusion is that these SNR values have to be met before the link will come up.
However the Speedtouch does not seem to drop the sync speed if these values are not achievable.
I need the eqivalent of the Conexant 'MaxDownRate' fix to reduce the down sync rate.
Anyone have any ideas?
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Hmmm option00 is probably minimum margin during training/negotiation and option01 is minimum margin during showtime i.e when the connection is up. Probably wrong tho.
Edited by JinxterX2 (Sat 10-Jun-06 12:38:37)
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DMT Modem Tool v7.18 is out
added: DMT-Server update (v0.75)
added: LineQuality ADSLv1 AnnexA (avg. noisemargin / grey bars) ; High/Low SNR Margin
added: attenuation downstream @300kHz and @1000kHz (only Annex B / T-Com Kontes-Orka)
added: estimated loop length calculation (in meters)
Just gets better and better
Edited by JinxterX2 (Sat 10-Jun-06 22:16:11)
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Someone's a busy little bee
Tim
Eclipse now ZeN
ST510v4 (4.3.2.6 CU Firmware) on 8 Meg Active
Check my bad boy speeds out on ZeN
Sign up for Latency Monitoring
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DMT Tool v7.19 is out
added: ability to set modemoption-values "on BIT base" (experimental area / modify-checkbox must be ticked)
added: ability to enable or disable Bitswapping
fixed: Telnet-Session Keep-Alive dont work if DMT-window lose focus
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Anyone had a play yet with the "on BIT base" enable or disable Bitswapping options yet? I meant to try them on the weekend but didn
Aaron Eldridge
ZeN Internet Technical support
ZeN are recruiting! Click here to view the opportunities available.
The opinions expressed here are that of my own and not that of ZeN Internet |
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The above post has been made by an ISP REPRESENTATIVE (although not necessarily the ISP being discussed in the post).
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Just noticed a post by EddieZ who is presumably associated with the tool development
http://forums.whirlpool.net.au/forum-replies.cfm?t=422001&p=-1#bottom
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Ok I need some help if you willing please.
my initial sync rate was I think 6292 and stable during the day.
then after about 11pm I had a desync and I think I had one earlier as well.
sync dropped to under 5700
I put in adsl faceplate and dumped the filter then sync went up to just over 6000, updated to that new firmware and now sync 5952
the snr ratio confuses me but I believe mine is very low and hence my desynchs.
speedtouch 546
Downstream Upstream
Margin [dB] : 6.5 21.0
Attenuation [dB] : 51.0 31.0
OutputPower [dBm] : 19.5 11.5
Available Bandwidth Cells/s Kbit/s
Downstream : 14037 5952
Upstream : 1056 448
Channel Mode : fast
basically I want to stabilise the line and ideally have no speed loss or just little speed loss
am I right my snr is 6.5db so already very low?
if so how do I raise it using dmt tool?
what affect is interleaving likely to have on my line?
edit - to add I ran the snr monitor interval for around 20 mins and the bottom graph was fluctuating upto 10 I think meaning 10%.
http://www.chrysalisnet.org/dmt230606_0036.png
thanks
nildram 8meg adsl
Edited by Chrysalis (Fri 23-Jun-06 00:36:38)
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Raise the slider for Target Noise Margin bit by bit and observe what happens, if the resyncs stop, leave it at that setting. Dunno much about Interleaving apart from it adds some latency, so if you're a gamer you probably don't want that.
Edited by JinxterX2 (Fri 23-Jun-06 02:12:34)
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ok this is what I done.
woke up checked adsl info, 109 resynchs over 5 hour period.
did you notice all the gaps on right side of middle graph in my frequency, whats that about? I defenitly dont see it on my freiends graph or on yours and you see where there is no gaps the db is at least 4 higher then average number worked out.
anyway I raised it as you said but lost a 1000kbit synch for a snr boost to 12db so lower it a little and now got 8.5 to 9db synch with a 5600 synch about 400kbit lost.
note this is daytime synch now at 10am the snr was exactly the same as last night on your graph with 3 lines plotted your snr is higher in the day shouldnt that happen for me as well?
should i ask my isp to enable interleave or leave on fast?
my adsl faceplate has a sky filter in the phone side is this possibly affecting the adsl? eg. i could put a phone extension in the sky side so the filter is nowhere near the adsl cable.
so now I have about 2-3 snr added and will see if stable like you said. please comment on my above points if you have any ideas thanks.
great help you have been and src of knowledge
nildram 8meg adsl
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just had another loss of synch
nildram 8meg adsl
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Try running ADSLMonitor to see what the error rates are like.
My problem is that with a long and noisy (at night) line I can get a high peak error rate causing a resynch even with an snr up at 12db
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Every image I've seen on this thread shows ADSL2+ selected implying this is what everybody uses when they adjust the SNM.
I'm surprised if you are all on ADSL2+ or is this the setting you should select whatever your connection.
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It doesn't matter about that setting, the router will select the correct modulation regardless.
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How long have you been on MAXDSL? Only a short time? 109 resyncs in 5 hours is a LOT, but if your target SNR margin in the DSLAM is set to 6db and you have such high attenuation, it's not unexpected to see so many resyncs. The BT DLM (Digital Line Managment) system should pick up on this eventually and raise your Target SNR margin by 3db until the line becomes more stable.
The gaps you talk about in the graph are normal, it's just the router masking out unusable, high frequency tones/carriers.
DLM might also turn Interleaving on for you anyway, if it decides it's needed.
You could try unplugging the Sky box from the phone socket and see if that makes a difference, dunno, don't have Sky myself.
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looked for that app earlier but couldnt find it via google, whats the url thanks
what I have noticed and dicussed in another thread is that my snr doesnt move up and down progressively, it has sudden drops mostly after around 120 tone upwards.
the drops vary but generally are big, and almost all the snr to the right of 150 on the graph. +8db went down to -7 in an instant in one of the drops which caused a desynch.
Now bt have raised my target snr and not had a desynch yet but obviously lost speed and still getting these drops which I think are putting me close to a desynch.
nildram 8meg adsl
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sky made no diff.
the BT system seems to have raised my target snr now after a LOT of desynchs.
can I ask you tho, in your experience is it normal for large snr drops to happen at a split second?
all my screenshots available here.
http://iroffer.us/adsl/chris/
I will be buying a shielded cable to see if it helps.
nildram 8meg adsl
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http://adslm.dohrenburg.net/
Google only works if you search for adslmonitor - no gaps
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If your line is subjected to some kind of impulse noise, then yeah, sudden drops in SNR margin can happen, high frequencies will be affected more than low ones. There's loads of things that influence adsl signals, you might have some local source of interference...keep your router as far away from the pc and monitor as possible or any other electronic equipment.
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currently its in a different room to the pc and there is nothing electrical near it in a big room.
nildram 8meg adsl
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I only linked to this post because of the very nice snr graph.
My snr db per tone graph tops out at about 180 running with a nominal snr of 14db at 3000kbps from router and showing an snr of between 22db and 30db (between 130 and 180) and about 10db (between 30 and 125)
Is this caused by the line generally or is it something I can affect myself
Edit - Oh dear I think I see the problem. the snr as reported by the router has dropped to 11db but snr reported by dmt in the 136 - 180 band is down as low as 3db and is mostly down below 8db
Edited by deleted (Mon 26-Jun-06 22:51:11)
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Bad news... According to the DMT forum web site, Speedtouch are planning to disable the CLI commands in future versions of the firmware which the DMT tool uses to source its information and to set the the various tweak options. Already, some people have been trying to persuade them that this would be a spectacular "own goal" and would almost certainly hurt their sales.
See 4th post down for details within the discussion forum:
http://forum.mhilfe.de/viewtopic.php?t=1622&postdays=0&postorder=asc&start=320
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DMT v7.20 is out
added: compatibility with older firmware-versions/commands (Menu Special --> Misc.Options --> FW spec.)
added: small improvements/bug fixes
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JinxterX2 - thank you for all your help by way of your posts - I hope you can help me some more, please!
I've recently purchase a 546 after seeing what can be achieved with the DMT tool; however I'm struggling to maintain a stable line. I game and as such stability is most important (as is a low ping). I've seen syncs as high as 6400 approx, but I find most stability happens around 5126. Is there any way, with my current gear, that I can stay around that speed?
I
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you might have the same problem as me that snr fluctuations mean that at one time of day you could tweak it to synch at 10snr and its the right sync but another time fo day it would be way too low and mess up your BRAS profile. This is why I had to stop forcing my router to synch at 9snr.
nildram adsl max
atten 50.5
line dist 1.66 straight
4400kbit to 6400kbit synch
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I would use the 'modify' checkbox instead of the slider and enter values directly into Register00 using only values like 08,10,18,20,28,30,38,40,48,50,58,60,68,70,78 etc. There is a slight flaw in the slider routine which can result in the wrong value being sent to Register00, I don't know if this has been fixed in the latest DMT but the author was made aware of the problem.
If you want to try and be stable at approx 5120kbps, you could try putting in various high values (during the daytime when the DSL signal should be strongest) until you sync near or at that speed, then pray it stays like that all the time, lol. A lot depends on if your SNR margin drops at night and what your Target SNR margin is set to in the DSLAM (higher the better if you have a noisy line).
I don't know what your 546 is like for generating heat but my 516v6 is like a mini heater, convinced this can't be good, I've put heatsinks on the 6338 chipset, RAM and Line Driver IC, plus cut a hole in the top of the case and inserted a small 12v fan Pretty sure it's helped stability and reduced CRC/HEC errors but I'll find out for sure over the next few days.
For true stability on MAX you'd need a router that did Tone Masking or allows you to set a maximum sync bitrate, there's a few around that do that kind of thing.
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Hi JinxterX2
Could you provide a list of these routers?
Phil
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For Tone Masking/Carrier Selection the Belkin 7633 (F5D7633uk4A) and US Robotics 9105 are two that I know of but haven't tested myself, for bitrate limiting, can't remember, but they have been talked about in this forum, so a search should reveal something.
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Thank you JinxterX2 - I'll try the checkbox, as advised. My 546 is ok for heat although I would say it gets warm to the touch. I have mine wall-mounted (cables going down). Is the snr in the DSLAM something that can be quite easily changed? I've heard that some of the Draytek kit will allow you to set a max bitrate; however one of my reasons for going with the 546 was price! I'm kind of hoping that this whole mess will somehow be sorted by BT, at some point :-)
Chrysalis - yes, my snr does vary quite a bit although not quite as much as yours it's still a problem nonetheless. Certainly not good when 1/2 way though an Unreal ONS match!!
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In reply to:
Is the snr in the DSLAM something that can be quite easily changed?
The BT line management system should change it automatically if it decides you have an unstable line.
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DMT v7.21 is out
added: support for displaying "adsl info"-data during SNR-observation (Menu Special --> Misc.Options)
added: Information-Panel-width (right side) is automatically adapted to current DMT-Window-width
fixed: wrong Resync/Retrain-recognition (red line) during SNR-observation. (only under certain circumstances)
fixed: small SNR-Slider inaccuracies (modemoptions)
fixed: DMT could not connect to Router (after Reboot) if DNS-Names were used instead of IP-Addresses
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my line is stable at night now but very sporadic in day.
http://bbs.adslguide.org.uk/showthreaded.php?Cat=&Board=btsupplier&Number=2549578
nildram adsl max
atten 50.5
line dist 1.66 straight
4400kbit to 6400kbit synch
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Mine has gone bonkers and so has my Speedtouch 516v6, lol, it can't hold sync for more than a few minutes now, I get the feeling BCM6338 chipset doesn't work very well with a Ti DSLAM, hooked up the Westell Proline 6100 (Ti AR7) and it doesn't drop the line but SNR is all over the place.
Bit of a difference in power levels between the two routers as well:
ST516 DS: 19.5dBm US: 12.0dBm
6100: DS 16.9dBm US: 11.0dBm
Obviously the Proline can command the DSLAM to cutback power, pity that doesn't work on the Speedtouch.
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I think BT need to redefine their broadband to "sometimes on" as I am having huge problems now, my signal to noise ratio has took a nosedive.
whats new in the dmt latest 2 versions thanks?
I believe I am connecting to an alcatel dslam.
nildram adsl max
atten 50.5
line dist 1.66 straight
4400kbit to 6400kbit synch
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Speedtouch 516v6 working fine today for some strange reason.
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Just checked - interleaving has been turned on. I'm a gamer, so a little concerned; however it's only added 9ms to my ping (I now ping at 31ms to jolt.co.uk), so could be a lot worse.
I've had loads of stability issues recently & hope that this sorts it all out! I'll keep you all posted on how it goes.
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New version of DMT Tool coming soon with support for the latest 6.1.4.6 UK firmware
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DMT Tool v7.22 is out
added: tdslDbg_getData_Limiter workaround
added: Language selection (german/english)
http://dmt.mhilfe.de/
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In reply to:
SNR Margin in DSLAM: 15db
How do you find out what the target SNR Margin is at the DSLAM?
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When do I try tweaking? During the 1st 10 days or after?
Thanks
------------------------------------------------
PIPEX
(Xtreme5)
Pipex GO! 2Mb(NDO Speed Test)/(Adsl Guide Speed Test)
Can'tWait4MaxDSL!!
Local Line Atten(dB): 46 Local SNR Margin(dB): 22
------------------------------------------------
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I dont suggest tweaking during the first 10 days.
nildram adsl max
atten 50.5
line dist 1.66 straight
4400kbit to 6400kbit synch
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WannabeMKII, yes that's a very pertinent question and one that I've doted on myself for quite some time. I can't give you an answer but my assumption all along has been that the downstream SNR value that we read in our routers or in utilities such as DMT is specifically a composite value. In other words, the user's router and the DSLAM may very well have their own 'programmed' SNR values for the line but, in practice, the two devices continually negotiate a combined SNR value for the line. I've therefore always wondered how JinxterX2, for example, has been able to declare that his DSLAM's SNR was 15dB. Did he really mean that, or was his 15dB figure, in fact, already a composite figure?
And what are the basic rules, anyway? Is it always the device negotiating with the lowest SNR value that effectively sets the agenda, or what? My gut feeling is that the composite SNR value is something that's not easily arrived at, and that, in fact, by trying to tweak the overall SNR from the user end, you're actually trying to tweak a moving target (since the SNR changes with network occupancy, local interference, etc).
It seems to me that the SNR tweakers amongst us need to adjust the value at the user end in such a way as to take account of the dynamic range of the SNR, under Max. Typically, this could be 3dB but, in some cases, could be considerably more. I think that, for instance in my own case, this is now as much as 6dB (12dB, down to 6dB). So, if my understanding about DMT is correct, getting an optimised SNR for the line - one that would guarantee the best speed but without fear of disconnecting - might well take weeks and weeks of experimentation. Am I right?
Edited by deleted (Sat 22-Jul-06 15:54:21)
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by default I think the router is set to allow the other end to set the target snr, when tweaked it overides the dslam.
wether or not BT have the ability to have the dslam overide the router I have no idea.
nildram adsl max
atten 50.5
line dist 1.66 straight
4400kbit to 6400kbit synch
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Re your first sentence, an interesting theory, Chrysalis. Trouble is, from the very moment you connect the router to the line, the router will presumably be applying its own default SNR value. After all, I've not seen or heard of any telnet command, for example, that turns the router's SNR specifically on or off. But you could well be right - the ruling you've suggested could well be workable. Presumably, though, that would mean that, once you've used the router to set the line SNR, you can never get back to the DSLAM being in control?
In essence, you're saying that the SNR value for the line is, in fact, NOT a composite value at all. It's an either 'router' or a 'DSLAM' value. Right?
Edited by deleted (Sat 22-Jul-06 16:30:26)
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I happen to have a router (Proline 6100) which always initially syncs at the DSLAM set target margin, so I just go by that.
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I think I agree, I dunno, if I had my 10 days over again...I'd probably tweak, but that's just me
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You can work it out because all MAX lines start off on a 6db target in the DSLAM (which my Proline 6100 confirmed when I first regraded to MAX), as time went on it was obvious from the router stats that the margin was being increased in 3db steps in the DSLAM.
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I guess I'm lucky at the moment then, as my SNR is currently sitting at about 5.5dB
I'm also lucky in that this doesn't vary by more than +/-1dB, so it's pretty stable.
It's interesting to read the difference in stat's from router to router though.
My router (DrayTek 2600VG) reports attenuation of 44.5dB and SNR of about 5.5dB and give's me about 4MB down.
Yet, my current router (Netgear DG834PN - DrayTek is in for repairs) has an attenuation of 51dB and 5.6dB SNR, yet I get 5MB down!
What's that all about?
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Yes, it was abundantly clear to me that my own initial target SNR had become 6dB, when I first changed over to ADSL Max. But, Jinxter, I thought you'd been saying that you yourself had started from a figure of 15dB? If it's the case that the DSLAM initially sets the target SNR and thereafter it's possible to override that with a user-configured value in the router, then either your particular DSLAM must have been initially wrongly set or you yourself must have increased the line's SNR at your end.
Having had some time to reflect on what Chrysalis and others have said, about which end takes command in terms of SNR, I'm inclined to agree with them. Everything's now kinda falling into place.
Actually, what happened in my case was that my initial 6dB margin was simply too low for my line to support and I therefore experienced very frequent disconnections in the evenings (like, every other minute). This was maddening and continued for some months, with the margin rising only to 8 or 9dB at best. Contrary to theory, the DSLAM didn't automatically bump up the SNR, to get me to a stable position. My ISP continually ignored requests from me to have the DSLAM's value raised by special request. It wasn't until the beginning of July that my ISP finally conceded, from disconnection statistics made privy to them, that my wholly unstable situation had been real and certainly hadn't been just a figment of my imagination. My ISP nevertheless continued to say nothing. However, from that day, my line then suddenly stabilised and, for almost a month now, I've not experienced a single disconnection. I still check my target SNR at different times of the day and, whereas before it only ever see-sawed between 6dB and 8dB, it now ranges from 6dB to 12dB, with it being mostly around the 9dB mark. I still don't know whether interleaving's been applied; my ISP won't tell me and my router doesn't show it. Possibly, it has. Instead of the hitherto ridiculous swings in sync speed, I now operate at between 4M bps and 4.7M bps, which I regard as being sensible sync speeds for my line, consistent with a high degree of stability.
I still plan to get myself a Speedtouch 546v6, though, as I'm keen to have something that'll perform well on my relatively long line (about 3.5km and 46 - 48dB attenuation), as well as having a facility to not only see whether interleaving is being used but also to set the target SNR from the router end, should that become necessary.
PS. Blow me down, I've just had a disconnection! Well, that's the first in a long time!
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same experience as me my snr was raised manually, I can probably explain why other people are maoning that their snr was raised too easy and why mine was never raised.
In another thread it appears me and one other person are not having all their resynchs logged by BT so the line is looking much more stable then it is, so if RAMBO thinks their isnt many resynchs it thinks the line is stable and doesnt adjust the target SNR appropriatly.
It is possible to go back to the dslam set target SNR after you tweaked by pressing the set/save default button, it has to reboot the router to do this.
nildram adsl max
atten 50.5
line dist 1.66 straight
4400kbit to 6400kbit synch
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In reply to:
But, Jinxter, I thought you'd been saying that you yourself had started from a figure of 15dB?
Yup, correct. But that's because I never got hold of a ST516v6 (and started tweaking) until after the DSLAM was set to 15db, which took about 2 months from the moment of regrade.
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Yes, sounds familiar. At the time that I had all of that disconnecting problem, I tried to find out whether and how BT regularly received information about my line. It seems that, with my particular ISP, BT regularly relays data to my ISP as to how many connections and disconnections (referred to as 'log-ins' and 'log-outs') are occurring on customers' lines, and at what times of day. But my ISP uses this information purely, it seems, to keep an eye on the capacity usage of customers like me who are on capped accounts. This data is, in fact, made available to us customers via the ISP's website. What I found nauseating for so long was that, though notified by me about it, my ISP took no notice of my excessive disconnections for several months. During that time, I was getting around 1050 disconnections per month and, in fact, had largely abandoned Internet usage in the evenings. My SNR didn't get automatically raised by the DSLAM, presumably because my particular pattern of disconnections somehow didn't meet the 10 or 12 per hour criterion. Anyway, after very protracted arguments with my ISP, it was finally conceded - though not expressed as such by my ISP - that my disconnect figures were unusually high and then, not long after, it all changed - everything became stable and my SNR moved higher. So, I'm pretty convinced that, in my case, BT's DSLAM certainly didn't automatically adjust my SNR. In the end, it was clearly done by some sort of manual intervention.
My line's now very stable (though still not 100%, as evidenced by what occurred late last night). I guess that what happened yesterday was that, owing to there being less traffic around, the modem/DSLAM decided to try to run the line faster and dropped the SNR accordingly, but then got caught out by a bit of crosstalk or interference. After it reconnected, I noticed the SNR had gone right down to 6dB again (but has now crept up once more). So curiously, it rather looks as though the average SNR has been raised, but the target SNR (the point at which disconnection ensues) is still 6dB. Either that or interleaving has been applied. (I confess I know little detail of how interleaving affects stability).
As for the DMT utility that can be used with Speedtouches, I'm pleased to learn from you that it has a means for cancelling control of SNR by the router and reverting to DSLAM control. I'm looking forward to getting and using a 546v6. That model's not quite officially on the retail market yet.
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Ah, I see. So, at the start, your DSLAM did what it was supposed to do and automatically adjusted the SNR upward, to 15dB. But then presumably, when you got your 516v6, you thought 15dB was overkill and so you used the 516 together with DMT to bring the figure down?
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Yup, exactly as you describe
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An old thread - time to put to bed
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The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
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