[WXC/VFX] Good modem for low SNR

Forums › One New Zealand (including Vodafone, WxC, Farmside) › [WXC/VFX] Good modem for low SNR

Trkstr

23 posts

Geek

#13025 18-Apr-2007 21:46

For the past 6 months or so now, i've been having a lot of trouble with my internet connection SNR dropping to a point where my WAG54G v2 would reset it self. Often, it would reset itself to a slower speed (around 1mbit or so). However, i find that if i just switch the cable from a filtered connection to a non-filtered connection, the modem resyncs at close to 8mbit.
Up till now, this has only happened once every couple of days or so.

But now, it is getting worse. It gets to the point where the connection would connect and be alright without any traffic. As soon as i try to load a web page, the SNR would drop like a stone and within 10 minutes, the connection would drop and resync at some rediculously slow speed.

I have spoken with telecom, they have apparently sent someone out to check the line and said that there is nothing wrong with the line.

So my question is, if i'm getting about 25db and 9db for my down and upstream attenuation, with very variable SNR, are there any modems that anyone would recommend that would maintain my connection and still give me decent speed (for a lot of what i need to do online needs good speed

) ?

Many thanks.

1 | 2

28189 posts

Uber Geek

Trusted

Lifetime subscriber

#67619 18-Apr-2007 22:22

Are you plugging your modem in thru a filter and expecting it to work properly?

Richard rich.ms

Trkstr

23 posts

Geek

#67623 18-Apr-2007 22:26

Um well the filter isn't really necessary as the line the broadband is on has only one jackpoint in hte house and no phones are connected on it.

richms

28189 posts

Uber Geek

Trusted

Lifetime subscriber

#67628 18-Apr-2007 22:45

Ok, so try plugging it in properly and see how it goes, if your getting an 8 meg sync then your line is great.

Richard rich.ms

Trkstr

23 posts

Geek

#68044 21-Apr-2007 23:02

Nope not getting an 8meg sync speed at all. The best i can get is about 3mbit. I've tried a lot of different modems (specifically: Linksys WAG54G, Netgear DG834G, and now the Dynalink RTA1320. All of them show a slowly declining SNR.

The connection was stable and constant when i was on a 2mbit plan with ihug. But not long after broadband was 'unleashed', i started getting my connection woes. Which is why i'm thinking it would be to do with the Te Atatu exchange i'm connected to not being able to handle the connections very well.

Another thought struck me was that there could be bad wiring in my house. There are quite a few lines coming into my house. What could i do to try and trace which and where my telephone line goes to?

richms

28189 posts

Uber Geek

Trusted

Lifetime subscriber

#68055 22-Apr-2007 12:02

Oh, the first post said 8 megs in it.

You are a victim of cross talk because of old poor cabling. Alcatal warned telecom of this that their network wouldn't handle the number of full speed connections, they did it anyway and this is the result. You can still find the PDF on telecoms network - http://www.telecom-media.co.nz/resources/adsl-performance-report-250706.pdf - this is when they went to 2 and 3.5 meg up from the 128 and 256 that most people had. It happened again at unleashing time.

I am in the same boat. Plus the dynajunk overheats when its on a long line and you move lots of data so get used to it crashing.

Someone I know who likes conspiracy theories says that they chose the name unleashed so people would confuse it with unbundle, so that the general populous now thinks that unbundling has stuffed up their internet. Seems to have worked too...

From the doc, read and then know what to ask about when you are moving house...

Based upon extrapolated measurements from the recent 2/3.5Mbps service upgrades and
available global evidence, a conclusion has been reached that the introduction of unconstrained
ADSL line rates will unavoidably affect the performance of some DSL services. Specifically,
DSL services configured on medium (2km to less than 3.5km) to long (>3.5km) copper access
binders, and some business services in the same copper access binders. This impact is also
expected to increase as ADSL service density increases within the same copper binder.

DSL services interfere with one another and other services that share the same copper binder.
A fundamental design principle for the deployment of the technology is to maintain adequate
noise margin for a service. With the increasing speeds, there is typically a decline in the
available noise margin, due to the increased frequency spectrum and power levels in use. This
is characterised by an increase in the line instability and a reduction in service speeds for rate
adaptive services such as broadband internet services. A customer would therefore experience
lower throughput.

Evidence of this impact can be seen in the recent national speed upgrade of Telecom
Wholesale and Retail broadband plans to 2Mbps and 3.5Mbps. There were 383,000 broadband
services monitored during the migration to the new plans. Of this number of services nearly
23% or 87,000 services could not achieve the new plan rates. In addition, 7% of customers
(16,118 of 235,027) on ASAM, which can be extrapolated to around 5% of all customers,
experienced a reduction in performance to below what they received prior to the upgrade.

If unconstrained line rates are implemented nationally, under the current network conditions,
there will be a wider service impact. Extrapolating the reduction in available noise margin from
the higher speeds, about 170,000 services (46%) are unlikely to achieve even the current rates
of 2Mbps and 3.5Mbps.

Richard rich.ms

xlinknz

1127 posts

Uber Geek

Trusted

#68132 23-Apr-2007 11:02

richms

Dynajunk - mines works - I am very happy with my rta1320 cost me $20 :)

That Alcatel paper, someone told me that commerce commission didn't think highly of it i.e. it was part of an attempt by TCNZ to put doubt in the minds of the powers that be when TCNZ were asked to provide more uncontrained bandwidth

I don't know but it does make for good reading esp. around dsl issues

Trkstr

23 posts

Geek

#68139 23-Apr-2007 11:57

Hmm...

So considering how Te Atatu is slowly being developed, with more and more people moving out west, i should only expect the situation to get even worse. Having only one exchange in the vicinity for both most of Te Atatu Peninsula and Te Atatu South.

How long do yal think it will take before telecom remedies the situation? I'm hoping that with more and more rich people moving into the neighbourhood, that something will be done.

I guess i can only wait and see...
An update on the situation so far, the Dynalink RTA1320 dropped the line about twice over a period of about 8 hours. Dropping the sync rate from about 2mbit in the morning before i left for work to about 500kbps when i arrived home. It looks like that this won't be good enough for me.

I might return it tomorrow.

Still no one has any other suggestions for good modems?

Quic Broadband

Move to New Zealand's best fibre broadband service (affiliate link). Free setup code: R587125ERQ6VE. Note that to use Quic Broadband you must be comfortable with configuring your own router.

xlinknz

1127 posts

Uber Geek

Trusted

#68150 23-Apr-2007 13:28

Trkstr

As richms points out - are you sure the modem is the issue ?

Trkstr

23 posts

Geek

#68184 23-Apr-2007 16:55

I originally thought it was the line. So i got the telecom to check the line. They said everything was ok and blamed Xnet.
I still think it's the line, but if telecom are not gonna do anything about it, then i can only look into getting a new modem.

xlinknz

1127 posts

Uber Geek

Trusted

#68202 23-Apr-2007 18:34

Firstly I mean the cabling in your home or even any line filters [I had one not so good filter]

Xnet helpdesk are typically excellent, you should find then helpful in getting some leverage with TCNZ - let them deal with TCNZ

I also suspect you will find xnet recommend the dynalink over many over brands

FYI these are the stats on RTA1320 and I get 2.6Mbit down and I use Xnet too

Line Mode	G.DMT	Line State	Show Time
Latency Type	Interleave	Line Up Time	00:08:37:26
Line Coding	Trellis On	Line Up Count	1

Line Rate	7616 Kbps	160 Kbps
Attainable Line Rate	8928 Kbps	864 Kbps
Noise Margin	14.8 dB	24.0 dB
Line Attenuation	26.0 dB	14.0 dB
Output Power	19.7 dBm	4.4 dBm

Trkstr

23 posts

Geek

#68216 23-Apr-2007 21:13

Wow that is pretty decent. My attenuation is similar to yours. However, my Noise margin sits around 11db at best. Dropping to about 6 db and then slowly drops to 1db at which point the connection dies.

My line rate maxes out at about 4000kbps on a good day (very rare) and the attainable line rate is about 100k higher than what the line rate is at the time. Often, after an hour at these rates, the modem disconnects and reconnects at about 1300kbps with slightly higher noise margin. and then about 3 hours later, the connection drops again, and reconnects at about 600kps at which point it will stay for the next 4 hours or until i reset it.

EDIT: slightly new advancement: If i have the modem and the phone plugged into the one jack point with an inline filter, i hear a little bit of static in the phone when the modem is on. However, when i pick up the phone, the modem disconnects and reconnects and i hear the static. When i put the phone down, the modem disconnects and reconnects again.

:(

richms

28189 posts

Uber Geek

Trusted

Lifetime subscriber

#68232 23-Apr-2007 23:25

xlinknz: richms

Dynajunk - mines works - I am very happy with my rta1320 cost me $20 :)

That Alcatel paper, someone told me that commerce commission didn't think highly of it i.e. it was part of an attempt by TCNZ to put doubt in the minds of the powers that be when TCNZ were asked to provide more uncontrained bandwidth

I don't know but it does make for good reading esp. around dsl issues

Oh yeah, they are fine on short lines, but they have quite widely known overheating issues when being asked to put out a decent signal for the upstream, like on a long crappy piece of telecom copper.

Richard rich.ms

richms

28189 posts

Uber Geek

Trusted

Lifetime subscriber

#68233 23-Apr-2007 23:28

Trkstr: Wow that is pretty decent. My attenuation is similar to yours. However, my Noise margin sits around 11db at best. Dropping to about 6 db and then slowly drops to 1db at which point the connection dies.

My line rate maxes out at about 4000kbps on a good day (very rare) and the attainable line rate is about 100k higher than what the line rate is at the time. Often, after an hour at these rates, the modem disconnects and reconnects at about 1300kbps with slightly higher noise margin. and then about 3 hours later, the connection drops again, and reconnects at about 600kps at which point it will stay for the next 4 hours or until i reset it.

EDIT: slightly new advancement: If i have the modem and the phone plugged into the one jack point with an inline filter, i hear a little bit of static in the phone when the modem is on. However, when i pick up the phone, the modem disconnects and reconnects and i hear the static. When i put the phone down, the modem disconnects and reconnects again.

Get a central splitter installed then, your filters are clearly not working properly.

Sometimes they will do it free if you have problems that just appear when there were none before.

Richard rich.ms

xlinknz

1127 posts

Uber Geek

Trusted

#68259 24-Apr-2007 09:12

agreed

I had one bad line filter [out of 4] and it caused noise on the telephone, I didn't check what it the problem filter did to my dsl as I wanted the phone fixed. I replaced the filter and then everything was good.

re the rta1320 - yes mine does get hot but it works fine for me, note I use it as a modem not as a router

trkstr - whatever modem you settle on make sure it supports adsl2+ so you future proof yourself

Trkstr

23 posts

Geek

#68350 24-Apr-2007 20:22

Sweet thank you all for the time that you guys have spent in this matter. :)

I will look into getting a central splitter.

Btw: just a quick plug for xlan coming to town in july :P yal know you want to check it out :P

1 | 2