Adsl Attenuation & Snr

[paulklee]

I have been having a three week "discussion" with True concerning my 6MB internet account. Previously this was quite dependable but a few weeks ago, it started performing intermittently, the majority of the time very poor performance, occasionally no connection. But occasionally, peak performance - <deleted>! About a week ago, a True 'engineer' called on motor-cycle and after eye-balling the street cables and connection boxes from ground level, declared them to be "good". Inside the house, he tested the connection before the router and said it was perfect, so it must be router. In fact the modem/router was a bit long in the tooth and I had been due to replace anyway (dlink G604T) si I bought a new one (dlink 2750U). Did a clean install from format of Windows 7, installed the new router - and guess what, no change. Highly intermittent service, with day-time drops - according to speedtest.net - to 0.2Mbps. So, another endless round of telephone conversations with True but nothing ever changes. They reset stuff at the exchange, they wave whatever black magic dead chickens they have - but nothing changes. A long diagnostic conversation with DLink - they think the modem is set up correctly, so we are back to True.

OK, rant over, here is the question. For those that know about these things, could they please comment on my router's attenuation and SNR Margin statistics and let me know what they might infer?

ADSL Down Up

SNR Margin (dB): 326 200

Attenuation (dB): 195 89

They seem high to me but I don't know their significance. I would be much obliged for any enlightenment and indeed what I might advise to True about these numbers. I have no idea how far we are from the supplying exchange - is that the DSLAM? I have been assuming something like a bad but intermittent connection (water filled connection box, then drying out etc etc) has been the culprit.

Many thanks in advance...

[Pib]

Your stats are good....they are actually being reported in tenths of db...that is, like your Down SNR of 326 is actually 32.6db which is an excellent SNR. Be sure to check your stats on the next disconnect to see if they change greatly.

You didn't mention what your modem/router stats reported for download and upload "sync" speeds. Since you said you have a 6Mb connection, your download "modem sync speed" should report 6144Kbs or maybe 7168Kbs depending on how the network is setup....this is your raw connection speed to the exchange/central station/DSLAM. The modem sync speed should be report in the same area where you got the SNR and attenuation stats.

You speedtest.net result of 0.2Mbps...where was that to?...the Bangkok speedtest server or somewhere else in the world?. If it was to somewhere like the U.S./Europe, unfortunately, it's no uncommon to get speeds that low with a lot of users online although your "in-Thailand" speed may be running 3 to 6Mb.

Here's a web site that gives a pretty good explanation of ADSL Lines Stats. Link

Also, here is a color coded chart to help with what SNR and Attenuation values are go or bad or in-between.

Here's another take on SNR and Attenuation:

SNR means Signal to Noise Ratio. Simply put divide the Signal value by Noise Value and you get SNR. You need high SNR for a stable connection. In general, a higher signal to noise ratio will result in less errors.

* 6bB. or below = Bad and will experience no line synchronisation and frequent disconnections

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

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

* 20dB-28dB. = Excellent

* 29dB. or above = Outstanding

Line Attenuation

In gerneral, attenuation is the loss of signal over distance. Unfortunately, dB loss is not just dependent on distance. It also depends on cable type and gauge (which can differ over the length of the cable), the number and location other connection points on the cable.

* 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

[paulklee]

Pib, Many thanks for the excellent reply and apologies for the delay in responding. Thanks for taking the time to explain the situation - by luck I had come across the kitz website that day so good reinforcement there. What I did not realise was that the Attenuation and SNR were being quoted in tenths of a db, I still can't see any reference to that (rather important!) fact. Thanks for letting me know.

I still have the intermittent performance problem tho I have given up talking to True about it, who knows, it may not be their problem. If you have a few more minutes, perhaps you could comment on the three graphics attached.

Sppedtest6sept shows the speedtest.net My Results for my adsl connection. The sheer volatility of the signal seems abnormal and the amount of time that the performance is high is quite limited. Occasionally (end Aug, beg Sept) performance almost disappears. The servers used for the tests are selected by speedtest.net, mostly Thai (sometimes thaivisa!) occasionally Cambodia. Do you see anything odd in this graphical profile? If that's just the way it is with True, so be it, I'll learn to live with it.

Second graphic is 'D-Link ADSL Router' stats 6 sept.png

This shows the basic stats I mentioned in the previous post. All seems OK?

Third graphic covers my router connection diagnostics -'D-Link ADSL Router' diags 6 sept.png. There are a number of FAILS shown here tho I suspect the three ETH connection fails are because I only have one LAN line connected? Any significance in the FAILS.

If Pib or anyone esle has a few minutes to comment on this stuff I would be obliged. Thanks in advance.

[Pib]

Regarding the first graphic, Speedtest does keep track of your results but it from the "servers you select to test to." So, if you were always testing to a server close to you, then you would probably always have good/high speed results. Like me in Bangkok...if I only tested to the Bangkok server and no other servers like servers to the U.S. I would always show good/high results. So, if you have been testing to a lot of international web sites which gives you a slower download speed (if speedtest.net is not giving it bogus/faster than light ping times/download speed results), I can see where your averages would be affected by those tests to international servers. Your other graphics look OK to me stats wise.

Since you are on True and if not doing so already, you might want to give True's proxy a try. I always use the proxy setting on my True cable 20Mb plans as it eliminates bogus speed test results and solves some access issue to certain web sites. The proxy setting is "proxy.trueinternet.co.th" with a Port setting of 8080.

If you are using IE8 (or similar version) you would enter this my selecting Tools, then Internet Options, then Connections, then Lan Settings, check the block for Use Proxy Setting for Your Lan and also check the block for ByPass Proxy Server for Local Addresses, enter in the Address block proxy.trueinternet.co.th and enter in the Port block 8080 and then click OK.

Now check and see how your internet works? It may or may not help. If you don't use a version of IE, then you can google on how to enter a proxy setting for your particular browser.

And if you notice you can't reach your modem/router setup menu after entering the proxy setting, just go back in like above and in the browser menu setting where you entered the proxy info, click the Advanced icon and then in the Exception block enter the modem/router's IP address as an exception...then you should be able to access the modem/router via Wifi not problem whenever you do need to access those menus. That's what I had to do.

Also, if you trying to connection to the internet on a "non-True" internet connection, like maybe while traveling in the airport, staying in a hotel, using a Wifi hotspot, etc, you will need to turn off the True proxy settings in that same menu where you entered the proxy info...just uncheck the proxy setting block. If you don't do this, while you'll still might make connection to the other internet connection/ISP you are tapping into, you won't be able to reach any web pages as you are trying to use a True proxy through another ISP. You have to be connected to the True network in order to use the True proxy.

Good luck...would be interested if it helps. I know it made my browsing more snappier, eliminated my speed test bogus result issue, and allowed to to reach a couple of sites which I couldn't reach before. Here's the True Customer Support Link that identifies the proxy setting and some other info. Link

[paulklee]

Pib, Hi again and thanks for the reply which will take me a few days to process and implement, so I will get back to you.

While searching for the CAT Parcel web tracking service, Google took me to this link http://www.cat.net.th/map/internetmap.html What a map! Worth a look! Amazing....

[paulklee]

Sorry about the delay in finalising this thread. Before I had a chance to implement Pib's suggestions above, other changes have come about. Current situation is that we now have True cable service for Internet with (so far!) consistent 10mb/1mb down/upload speeds. The story if you want to read on:

It was a struggle to get the cable service, True insisted that cable service was not available in our area but we already have cable Truevisions. Luckily, an engineer came out to investigate our previous ADSL problems and confirmed that we could have True cable internet service, as "the box" was just outside of our house! But True customer service still insisted that there was no cable service.

Anyway, this engineer organised our application for the service and came along and installed it when the paperwork was ready, installing a cable modem as part of it all. The "installation" involved splitting our existing TV cable, one end to the TV box, the other end to the new cable modem. Internet service was working within seconds and the team of three involved were in the house for less than 20 mins. We were very lucky to get that engineer who kind of cut through the call-centre BS to get it installed. My wife gave the team a very modest tip for this excellent service but they truly (pun seen and noted were not looking for money.

Anyway, two days later True calls up and asks for our exact address because they are trying to identify if there is "a box" in our area. Boy were they surprised when we told them that the service was already installed!

It seems that the problem of being two companies leads to poor reporting of available infrastructure. Truevisions put in the original cable Tv service earlier in the year but that cable availability was not showing on the True internet service availability maps. Left hand, right hand. Actually, the whole situation cost me about 2000B cos the very first True engineer who came out about the ADSL problems absolutely guaranteed me that the problem was my modem/router. I bought a new one and a couple of weeks later that is redundant as I have a sparkling new cable modem from True with 4 wireless channels built in. Guess I'll have to sell the modem/router (dlink 2750U if anybody wants to make a bid!

Just tested the service again and it is 10/1, so no complaints from me about the new cable internet service. Pib, any special circumstances, set-up specifics I should consider for the cable modem service. Is the proxy advice still relevant?

[Pib]

Good deal. Using True's proxy is strictly up to you. It does fix some problems such as: giving you realistic speed test results (i.e., no bogus faster than light ping times or bogus 10Mb download speeds to any server on Earth), allowing access to certain U.S. govt web sites such as the U.S. Embassy American Citizen Services Appt System (maybe important if you are a U.S. citizen), and may speed up your browsing/downloading a little. Even if you don't want to use it all of the time you probably still should get it working in your setup and then just turn it on when needed to do speed tests, reach certain U.S. govt web sites (mabye others), etc. Once the proxy is setup in your browser it's pretty faster to turn it off and on.

Good luck with your service. My 20Mb/2Mb plan is still working fine after 3.5 months..except for an 8 hour period about two weeks ago when both cable TV and cable internet was down in my whole area of western Bangkok (probably some truck crashed into a pole somewhere or a backhoe dug up some fiber line), the service has been fine. As soon as the cable TV came back on, the internet service came back on also.

[lopburi3]

I use True; but do not use proxy, and have no issues with US Embassy ACS (or any other US Government) access. Believe that is a cable system issue only rather than TRUE ADSL or dial-up problem.

[Pib]

I use True; but do not use proxy, and have no issues with US Embassy ACS (or any other US Government) access. Believe that is a cable system issue only rather than TRUE ADSL or dial-up problem.

Correct. Apparently it don't affect True ADSL customers. I expect there are some different servers/certificates in use between the ADSL and Cable networks. Hard telling what is causing the issue and maybe it will go away in the future (or not). I know when I have the True proxy turned off I have a 110 series IP address; with the proxy turned on I have a 203 series IP address.

[lopburi3]

I currently have a 110 address using ADSL and have confirmed no problem with ACS appointment access. Must be something else causing it.

[Pib]

I currently have a 110 address using ADSL and have confirmed no problem with ACS appointment access. Must be something else causing it.

Yea, could be a certificate thing on a cable server. I know it not just an issue with me since other people on cable and even other ISP's ADSL systems are having the problem according to other posts in other topics. The only way for me to reach those certain U.S. govt web sites is to turn the True proxy on or use VPN. And I didn't have this issue when with TOT or JINET.