Adsl Help

[bluechipit]

I wrote this as a reply on the Samui forum but thought I'd post it here in case it helped some people with the huge list of Internet problem posts I see here every day.

TOT & TT&T have been installing more mini DSLAM's around the island like crazy, connected with fibre optics - which has improved things tenfold The DSLAM is where your phone line ends up. Even if you have a bad SNR, say a reading of 10 (below ten and you're on dodgy ground...) a good modem like the Thomson Speedtouch 536 (I consider these the best out there) will hold the line steady.

I used to be live out a Chansuwan, Lamai and had a 4km line ran for me to my house. I had a 3mb line an SNR of 6 and ATT of 60! - With the Speedtouch it held steady even in the worst of the rain (the SNR would drop to 3 sometimes!) Remember a modem will only connect at the fastest speed possible the line can provide and a decent one will drop the line speed to cope with the SNR. It's like driving your car down a bumpy road, you'd slow down for the bumps.

One thing to check is your junction box outside, these corrode inside pretty badly due to the sea air and bad fitting. Open this up, undo the nuts, remove wires and give it a good clean with the wire brush then put it back will help. Also check your internal wiring as that's where a lot of faults lie.

If you just have a modem and no telephone, remove that adsl filter, you don't need it - it's only to filter the adsl sounds out from the phone line so you don't hear them when having a conversation.

Also DOUBLE check and I mean DOUBLE check it has the correct grounding wire connected to the centre nut and the ground wire goes down in to a grounding rod in the ground. If it doesn't, call them out to install it, or do it yourself. I can't stress enough this is essential to save your equipment in a nearby lightning strike. Also make sure your phone line goes in to the telephone surge protector of a grounded UPS before it goes to your modem - and don't let any idiot engineer remove this!

I've lost a hundred thousands bahts worth of wireless equipment because an engineer unplugged the phone line from the UPS and plugged it straight in to the modem bypassing the anti-surge. I wasn't on site when they checked the line and decided to do this. That night there was a close lightning strike (sods law!) and the surge went up the phone line in the modem, out of the modem in to a switch, then out in to 3 sets of very expensive wireless equipment. It was toast.

The firmware on the old modems wasn't great either, they used to set the ADSL modulation to ADSL2 all the time, when really D.GMT or (ITU-T G.992.5) is the most stable for connections up to 8Mb.

Changing this for clients made a huge difference, or swapping their cr*ppy modem for a Speedtouch worked wonders. The Speedtouch always selects ITU-T G.992.5

I run all my modems in bridge mode (to do the ADSL part) and have a network platform running the PPPoE which means if the line drops out, no more physically resetting the modem, the network platform remakes the PPPoE connection automatically. I also run a good quality UPS on all my modems/installs. APC is the only brand to use.

[Tropicalevo]

Thanks for the info - I just with that I understood the other half of it :-)

[woodyleonhard]

Excellent advice.

Where can you get a Thomson in Thailand?

[bluechipit]

Excellent advice.

Where can you get a Thomson in Thailand?

PM me and I'll give you the address of my supplier. I'm not interested in making a daft 300 baht for selling one on...

[astral]

I have pinned this excellent topic at the top of the forum to increase visibility.

[Prasert]

About the signal-noise ratio:

With ADSL version 1 (G.DMT) you need a SNR of 10dB or higher. This number applies to 512k/2M lines. But when speeds go up, the SNR drops. A 1M/8M line (which is the maximum for ADSL version 1) can have a SNR of 11dB down and 5.5dB up, still stable and performing fine.

With ADSL2 and ADSL2+ this SNR story changes. SNR values can be much lower, as more bandwidth on the copper line is used (in smaller frequency bands).

Example on a 3km line:

downstream/upstream: 10M/2M SNR: 13.5dB/12.3dB

downstream/upstream: 15M/2.4M SNR: 6.1dB/7.7dB

[bluechipit]

Prasert is definitely your guy for ADSL help! How's it going Prasert, long time no speak?

Definitely correct about SNR readings but you really need to leave some overhead for conditions, i.e. rain, etc.

Here's a small guide to both SNR and attenuation:

For S/N Margin Readings:

6bB. or below = Bad and will experience no line synchronisation or intermittent synchronisation problems.

7dB-10dB. = Fair but does not leave much room for variances in conditions.

11dB-20dB. = Good with little or no synchronisation problems

20dB-28dB. = Excellent

29dB. or above = Outstanding

Attenuation Rates:

20bB. and below = Outstanding

20dB-30dB. = Excellent

30dB-40dB. = Very Good

40dB-50dB. = Good

50dB-60dB. = Poor and may experience connectivity issues

60dB. and above = Bad and will experience connectivity issues

Matt.

[bluechipit]

This is also a very handy line speed calculator, so you can work out your maximum speed.

ADSL Line Speed Calculator

Matt.

[Supernova]

Having experienced connectivity issues in the past with nowhere to turn to for help, I spent a lot of time researching about ADSL on the web. Here's a "shortlist" of resources I've found to be useful. If you run into problems, be sure to check them out...

A. General Troubleshooting

• Connection Problems
  
• Repetitive Electric Impulse Noise
  
• How to interpret your adsl Line Stats
  

B. Tests and Diagnostics

• ICSI Netalyzr
  
• The Glasnost Project
  
• Broadband Tests and Tools
  

C. Wiring tips for ADSL

• Typical Wiring Configurations
  
• Phone-man's Home Phone Wiring Advice
  

D. Connection Monitoring Software

• DMT (DSL-Modem Tool)
  
• RouterStats
  

[bluechipit]

Great Post Supernova!

[Prasert]

Supernova has posted some links to good theoretical information about ADSL. However, the situation here in Thailand has a few extra headaches:

Practically all telephone lines run 6m above the ground, and so do the 220V power lines.

Thai electric installations usually lack grounding and the use of a GFCI, a Ground Fault Circuit Interrupter. In many places wiring is so bad in houses/shops/etc. that current is leaking away and this causes a magnetic field around a power line (this field would trigger the GFCI, indicating you have a wiring problem!).

Add all these poor installations up, and the result is a big magnetic interfering field along the poles, where the phone lines are running as well.

TOT phone lines are usually 2 non-twisted copper lines and a steel cable for strength/support (8-figure dropline). CAT uses a twisted copper pair with a steel cable, which performs better and is a little bit less susceptible to interference.

And rain is also influencing the signal quality. Even perfectly insulated phone lines are affected during rain, as the magnetic interference changes dramatically due to bad insulation of power lines.

The only cabling not affected by this, is fiber. But it's still a hel_l of a lot more expensive than copper.

Another option would be to put the cable into the ground, but Thai land laws make this basically impossible.

[bluechipit]

TOT phone lines are usually 2 non-twisted copper lines and a steel cable for strength/support (8-figure dropline). CAT uses a twisted copper pair with a steel cable, which performs better and is a little bit less susceptible to interference.

Prasert, I thought twisted pair was a bad idea for ADSL as it doubles the length of the cable (due to the twist) which increases attenuation?

Matt

[Supernova]

Practically all telephone lines run 6m above the ground, and so do the 220V power lines. Thai electric installations usually lack grounding and the use of a GFCI, a Ground Fault Circuit Interrupter. In many places wiring is so bad in houses/shops/etc. that current is leaking away and this causes a magnetic field around a power line (this field would trigger the GFCI, indicating you have a wiring problem!).

+1

So true. It's a miracle we even have ADSL at all...

Prasert, I thought twisted pair was a bad idea for ADSL as it doubles the length of the cable (due to the twist) which increases attenuation?

Matt

To the contrary, twisted pair is good for ADSL. All my internal wiring is done with UTP (unshielded twisted pair / CAT5e). I've definitely seen an improvement in overall line stability. I can't say for certain about the copper lines outside the home... My guess is that it's probably not twisted pair since the line itself is almost 20 years old. The black dropwire isn't -- that much I know for sure.

I don't think twisted pair cable increases line length. Even if it did, the increase is probably negligible.

Edited June 20, 2010 by Supernova

[bluechipit]

To the contrary, twisted pair is good for ADSL. All my internal wiring is done with UTP (unshielded twisted pair / CAT5e). I've definitely seen an improvement in overall line stability. I can't say for certain about the copper lines outside the home... My guess is that it's probably not twisted pair since the line itself is almost 20 years old. The black dropwire isn't -- that much I know for sure.

I don't think twisted pair cable increases line length. Even if it did, the increase is probably negligible.

Sure, for internal wiring. I'm taking about the outside ADSL lines spanning thousands of meters or so...

Matt.

[Prasert]

Twisted pair is better than no-twisted.

The big black aerial cables that have 12/24/48 or more pairs inside are all twisted pairs. Each pair has a different number of twists-per-distance to reduce crosstalk. When you strip the insulation of UTP cable, you can see that the 4 pairs each have a different number of twists.

About the length - I think it's a matter of centimeters per 100m, not really interesting.

The diameter of the copper used also makes a difference. Generally 2 flavors are available here ibn Thailand: 0.4mm and 0.9mm. On shorter distances (up to 500m), the 0.4mm has better signal quality, for longer distances 0.9mm has the best results.

Check the Wiki page for details.

[bluechipit]

I'd take Prasert's advice on this any day. He certainly knows his stuff.

[Andine]

Hi there!

I'm a newby on this forum ... Used to be in comms long ago ... in OZ.

I'm in a condo at Nonthanburi .. Riverine towers . The computer link is mad .. it switches on and off willy nilly.

I contacted the local IT guy ... He came to fix ... He connected up a router with a meter of Cat 5 cable to my computer ... See it runs @ 100 meg! ... WoW!

Ok .. from the router it goes into a shared phone line flat cable ( no twists ) and then down to the basement ... About 100 meters easy! ... No wonder it does not work!

I pointed this out ... So he moved my house phone to the Throne room ( the only other line he could find ) .. Then he conected the flat phone cable to The local WIFI ( Which also does not work well) ... cat 5 cable to go to the other system ... !!

That kluge resulted in a bit more through put! It still switches on and off ... listening to my home radio station is sort of spasmodic .

A fair amount of this stuff goes by Microwave ( I think ) as it drops out when there is a rainstorm, and direct visibility is impaired.

The ping test shows a high dither rate .. I'd surmise that SNR is very poor.

Question ... I'm about to launch into a bit of traveling .. Is it possible to get a satelite dish ( there used to be a folding one available ) .. and get a connection that way?

I could just point it at the sky from the car !!

Now that would be one-upmanship!

Andine !!

[Prasert]

I contacted the local IT guy ... He came to fix ... He connected up a router with a meter of Cat 5 cable to my computer ... See it runs @ 100 meg! ... WoW!

And you used to be in comms??????

Ok .. from the router it goes into a shared phone line flat cable ( no twists ) and then down to the basement ... About 100 meters easy! ... No wonder it does not work!

I pointed this out ... So he moved my house phone to the Throne room ( the only other line he could find ) .. Then he conected the flat phone cable to The local WIFI ( Which also does not work well) ... cat 5 cable to go to the other system ... !!

Nearly all droplines between the houses and the distribution boxes are untwisted copper pairs. A DSL signal will easily travel over 5km of untwisted copper, it's just more susceptible to electromagnetic interference than twisted-pair cabling.

Is it possible to get a satelite dish ( there used to be a folding one available ) .. and get a connection that way?

Are you serious?

[Andine]

I contacted the local IT guy ... He came to fix ... He connected up a router with a meter of Cat 5 cable to my computer ... See it runs @ 100 meg! ... WoW!

And you used to be in comms??????

Ok .. from the router it goes into a shared phone line flat cable ( no twists ) and then down to the basement ... About 100 meters easy! ... No wonder it does not work!

I pointed this out ... So he moved my house phone to the Throne room ( the only other line he could find ) .. Then he conected the flat phone cable to The local WIFI ( Which also does not work well) ... cat 5 cable to go to the other system ... !!

Nearly all droplines between the houses and the distribution boxes are untwisted copper pairs. A DSL signal will easily travel over 5km of untwisted copper, it's just more susceptible to electromagnetic interference than twisted-pair cabling.

Is it possible to get a satelite dish ( there used to be a folding one available ) .. and get a connection that way?

Are you serious?

Thank you for your response ..!

Yes I was in comms about 20 years ago .. These days I'm retired.

I actually wanted a bit of help ... Had I wanted ridicule I would have asked for it!

To explain ... I do understand that just because the router tell my computer that it is running at 100 megs .. this does not signify that the link is doing that .. The man installing that was trying to tell me so. Obviously your comms knowledge ( which I do not doubt ) exceeds your knowledge of the english language!

This building was wired many years ago .. and I'm unsure of the standard of the wiring .. It probably runs in the same ducts as power cables as it was likely only intended for telephone use.

The through put of the link varies from about 1.5 megs to 4 megs as measured by speed test .. The ping test shows a large variation in the results for "Dithering"

1.5 megs would be fine for what I do .. but during the day the link varies in how often it disconnects .. so sometimes its connects and disconnects rather a lot, and becomes highly degraded. Trying to download anything at that time is pretty useless.

As to satelite dishes .. There are plenty of those available for mobile homes in europe, and they supply a variety of uses, including the internet. I was wondering if anyone here had experimented with that solution.

Best regards

Andine !!

[Olli]

I contacted the local IT guy ... He came to fix ... He connected up a router with a meter of Cat 5 cable to my computer ... See it runs @ 100 meg! ... WoW!

Just about the 100 Mbps: it's the Ethernet connection from your computer to the router. If you have a 1 Gbps NIC in your computer, it would show: 1 Gbps (1000 Mbps)!!

[Andine]

I contacted the local IT guy ... He came to fix ... He connected up a router with a meter of Cat 5 cable to my computer ... See it runs @ 100 meg! ... WoW!

Just about the 100 Mbps: it's the Ethernet connection from your computer to the router. If you have a 1 Gbps NIC in your computer, it would show: 1 Gbps (1000 Mbps)!!

Yes ... that is what I was refering to!

[Eureka]

Thank you for your response ..!

Yes I was in comms about 20 years ago .. These days I'm retired.

I actually wanted a bit of help ... Had I wanted ridicule I would have asked for it!

To explain ... I do understand that just because the router tell my computer that it is running at 100 megs .. this does not signify that the link is doing that .. The man installing that was trying to tell me so. Obviously your comms knowledge ( which I do not doubt ) exceeds your knowledge of the english language!

This building was wired many years ago .. and I'm unsure of the standard of the wiring .. It probably runs in the same ducts as power cables as it was likely only intended for telephone use.

The through put of the link varies from about 1.5 megs to 4 megs as measured by speed test .. The ping test shows a large variation in the results for "Dithering"

1.5 megs would be fine for what I do .. but during the day the link varies in how often it disconnects .. so sometimes its connects and disconnects rather a lot, and becomes highly degraded. Trying to download anything at that time is pretty useless.

As to satelite dishes .. There are plenty of those available for mobile homes in europe, and they supply a variety of uses, including the internet. I was wondering if anyone here had experimented with that solution.

Best regards

Andine !!

I truely wonder about your claim to have been in "COMMS" particulary in any of the Technical areas, maybe tele-marketing, as you cannot provide data of a useful nature or even in a professional manner. Any technician requesting assistance in his field of endeavour would not have problems with basic terminology or principles. Maybe exploring the acronyms WAN and LAN and also megabyte & megabit.

No everyone can be an expert but those who ask for information do not generally attack the respondant's language skills, which by the way appear to be of at least an equal level to your own.

[Prasert]

Thank you for your response ..!

Yes I was in comms about 20 years ago .. These days I'm retired.

I actually wanted a bit of help ... Had I wanted ridicule I would have asked for it!

To explain ... I do understand that just because the router tell my computer that it is running at 100 megs .. this does not signify that the link is doing that .. The man installing that was trying to tell me so. Obviously your comms knowledge ( which I do not doubt ) exceeds your knowledge of the english language!

I guess Eureka already posted exactly what I was thinking....

I truly wonder about your claim to have been in "COMMS" particularly in any of the Technical areas, maybe tele-marketing, as you cannot provide data of a useful nature or even in a professional manner. Any technician requesting assistance in his field of endeavor would not have problems with basic terminology or principles. Maybe exploring the acronyms WAN and LAN and also megabyte & megabit.

No everyone can be an expert but those who ask for information do not generally attack the respondent's language skills, which by the way appear to be of at least an equal level to your own.

I can add to this, that I'm not native english, although I do perfectly understand correct English.

About your wiring: this topic has already several posts mentioning all the factors involved in a DSL connection (SNR, Attenuation and output values). Although you do not clearly describe the problem you're experiencing, the cabling mentioned by you is pointing in this direction. And because of your claim to be in comms, I don't think it would be necessary to guide in you in every single step of diagnosing the issues you're experiencing. Doing that would be really ridiculing you.

As to satelite dishes .. There are plenty of those available for mobile homes in europe, and they supply a variety of uses, including the internet. I was wondering if anyone here had experimented with that solution.

Here in Thailand you can get satellite internet from CSloxinfo and TOT. Both use the same satellite for their IPstar service. Their satlink (Ku-band) provides both the upstream and downstream link, which requires an extremely perfect aligned dish of at least 80cm. The signal requirements are way higher than a simple (unidirectional) satellite-TV link. Something you won't achieve with a fold-able mobile dish. If you want mobile connectivity, stick to a GPRS/EDGE/3G connection.