Telecom ADSL2+; quality of signal

Forums › Telecom New Zealand, XT Network, Yahoo!Xtra › Telecom ADSL2+; quality of signal

steve2222

159 posts

Master Geek

Topic # 90868 1-Oct-2011 14:14
The attached is a screen grab from my router. I have seen on an overseas forum that the SNR should be over 10db - so mine is okay. But the same forum suggested the noise level should be no more than 1db for each km the line takes back to the exchange. Give I am about 3 to 4km from the exchange (depending on exactly which route the Chorus cable takes), my noise level is way over this at 16 to 33db. Is this an issue? What readings do others have? http://www.geekzone.co.nz/imagessubs/blog6c56b90c44e13387ef709552328fef7b.jpg

1 | 2

1327 posts

Uber Geek

Reply # 528013 1-Oct-2011 14:28
The SNR is basically a target that the modem aims for when negotiaing a speed when it connects - it is set at 12dB for you, but you may see it flutate slightly from there. Different (often overseas) providers will set this at a lower level, but the trade-off is usually decreased reliability. The 33dB attentuation you are seeing would be about right for the distance you are from the exchange. The actual connect speed does look slightly on the low side for your attenuation level. What is your internal house wiring like?

steve2222

159 posts

Master Geek

Reply # 528016 1-Oct-2011 14:35
Thanks for that. Couple of years ago (with Cyril7's help and supply of product) I switched from ADSL filters to an ADSL splitter. The data cable side of this goes direct from the splitter to the router over a distance of about 20m. It was new cable when I did this work. I have seen the download speed up around 9mbs before.

RunningMan

1327 posts

Uber Geek

Reply # 528019 1-Oct-2011 14:50
steve2222: Thanks for that. Couple of years ago (with Cyril7's help and supply of product) I switched from ADSL filters to an ADSL splitter. The data cable side of this goes direct from the splitter to the router over a distance of about 20m. It was new cable when I did this work. I have seen the download speed up around 9mbs before. Your cableing should be fine then - Cyril knows what he's doing! I would have thought you would have got a little closer to 9Mb/s with 33dB attenuation though, but sometimes there may just be a bit too much noise on the line out of your control. Have you checked to make sure you have the latest firmware for your modem? Also, if you can borrow another brand of modem to try as well - there are several which are generally thought to perform better than the older D-Links.

eluSiveNZ

23 posts

Geek

Reply # 528031 1-Oct-2011 16:07
steve2222: The attached is a screen grab from my router. I have seen on an overseas forum that the SNR should be over 10db - so mine is okay. But the same forum suggested the noise level should be no more than 1db for each km the line takes back to the exchange. Give I am about 3 to 4km from the exchange (depending on exactly which route the Chorus cable takes), my noise level is way over this at 16 to 33db. Is this an issue? What readings do others have? http://www.geekzone.co.nz/imagessubs/blog6c56b90c44e13387ef709552328fef7b.jpg Ive got the exact same noise levels as you. I am getting 9595Kbps/1095Kbps I was getting 11000KBps and 600Kbps a few days ago, but my upload went up and my download went down!?

steve2222

159 posts

Master Geek

Reply # 528033 1-Oct-2011 16:10
eluSiveNZ: Ive got the exact same noise levels as you. I am getting 9595Kbps/1095Kbps I was getting 11000KBps and 600Kbps a few days ago, but my upload went up and my download went down!? How far from the exchange are you?

RunningMan

1327 posts

Uber Geek

Reply # 528185 2-Oct-2011 10:39
Bear in mind that everbody should have the same SNR (signal to noise ratio), and that should be 12dB, or very close to it. In general terms, the only exceptions will be people who have specifically had this altered by request, or I think one ISP using their own equipment set a lower SNR target. The attenuation figure (in your case 33dB) should correspond to the distance you are from the exchange or cabinet (by whatever route the physical cables run). A lower attenuation means you are closer to the exchange, a higher number, further away. The higher the attenuation, the slower your connection will sync at.

Spyware

958 posts

Ultimate Geek

Subscriber

Reply # 528187 2-Oct-2011 10:50
With 33 dB attenuation the cable run is a little over 2 km. You should sync way higher with this attenuation and maybe get 12 Mbps down. To get that though you need to dump the 604T, even though it claims adsl2+ support the reality is another matter. Ross ADSL2+ sync (Kbps): 11577/945, attenuation (dB): 33.0/16.9, Noise margin (dB): 11.5/11.5

steve2222

159 posts

Master Geek

Reply # 528190 2-Oct-2011 10:58
Spyware: With 33 dB attenuation the cable run is a little over 2 km. You should sync way higher with this attenuation and maybe get 12 Mbps down. To get that though you need to dump the 604T, even though it claims adsl2+ support the reality is another matter. Thanks Spyware - any recommendation for alternative router? I prefer one with LAN and Wireless.

steve2222

159 posts

Master Geek

Reply # 528193 2-Oct-2011 11:00
RunningMan: Have you checked to make sure you have the latest firmware for your modem? Also, if you can borrow another brand of modem to try as well - there are several which are generally thought to perform better than the older D-Links. Thanks Running Man - any recommendation of a suitable router to use with Telecom/Xtra that has LAN and Wirelss.

steve2222

159 posts

Master Geek

Reply # 528194 2-Oct-2011 11:02
steve2222: The attached is a screen grab from my router. I have seen on an overseas forum that the SNR should be over 10db - so mine is okay. But the same forum suggested the noise level should be no more than 1db for each km the line takes back to the exchange. Give I am about 3 to 4km from the exchange (depending on exactly which route the Chorus cable takes), my noise level is way over this at 16 to 33db. Is this an issue? What readings do others have? http://www.geekzone.co.nz/imagessubs/blog6c56b90c44e13387ef709552328fef7b.jpg Whoops - checked the other forum and it actually says attenuation should be about 1db per 100m - not per km as I suggested. So my 33db is not bad given my exchange distance as other posters in this thread have suggested. Now to improve the download speed - maybe with a new router.

Spyware

958 posts

Ultimate Geek

Subscriber

Reply # 528199 2-Oct-2011 11:09
steve2222: Spyware: With 33 dB attenuation the cable run is a little over 2 km. You should sync way higher with this attenuation and maybe get 12 Mbps down. To get that though you need to dump the 604T, even though it claims adsl2+ support the reality is another matter. Thanks Spyware - any recommendation for alternative router? I prefer one with LAN and Wireless. CISCO887W-GN-A-K9, can be got for $900 or so. Also a VDSL/ADSL variant for same price. IPSec VPN is handy for VPN between home and work. Ross ADSL2+ sync (Kbps): 11577/945, attenuation (dB): 33.0/16.9, Noise margin (dB): 11.5/11.5

sbiddle

16712 posts

Uber Geek

Moderator

Trusted

Biddle Corp

Subscriber

Reply # 528201 2-Oct-2011 11:12
steve2222: Spyware: With 33 dB attenuation the cable run is a little over 2 km. You should sync way higher with this attenuation and maybe get 12 Mbps down. To get that though you need to dump the 604T, even though it claims adsl2+ support the reality is another matter. Thanks Spyware - any recommendation for alternative router? I prefer one with LAN and Wireless. If DSL signal quality is important get a TP-Link. *Need help configuring your Linksys ATA or IP Phones for New Zealand? Check my blog post

Ragnor

6894 posts

Uber Geek

Trusted

Subscriber

Reply # 528352 2-Oct-2011 23:08
RunningMan: Bear in mind that everbody should have the same SNR (signal to noise ratio), and that should be 12dB, or very close to it. Noise margin and Signal to noise ratio are two different things, some older modem/router models don't label them very clearly though. You are thinking of noise margin on any connection provided over Telecom wholesale equipment which is normally 12dB. I belive Orcon, Vodafone and Slingshot use 6dB on their LLU gear allowing for higher line rates at the risk of less stable lines.

RunningMan

1327 posts

Uber Geek

Reply # 528364 3-Oct-2011 00:11
Ragnor: Noise margin and Signal to noise ratio are two different things, some older modem/router models don't label them very clearly though. You're quite right - getting my acronyms confused by typing faster than I think!

eluSiveNZ

23 posts

Geek

Reply # 528380 3-Oct-2011 07:28
steve2222: How far from the exchange are you? Im about 2.5K from exchange.

1 | 2