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Target SNR margin

mapletree
Grafter
Posts: 644
Registered: 28-07-2007

Target SNR margin

What reasons would your target SNR margin rise that would not be obvious?  My target SNR margin has risen to 15dB recently, despite me not noticing any disconnections.  Once the router connects at a particular speed I have not noticed any speed reductions.  I have been monitoring my actual SNR margin and it mostly varies between 12-14dB.  It has never dropped below 11dB.
I have checked the obvious: wiring, phone, microfilters, router etc.
14 REPLIES
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: Target SNR margin

You got any idea what the error counts are like. especially when your snr drops low in the evening?
Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: Target SNR margin

As I've already explained in the other thread, too many disconnects, or as ASBO has mentioned - errors.
Having had a quick read through some of your previous posts, I think the only way to get to cause of this is by some serious monitoring.
You will need to use which ever of your better routers will work with RouterStats - http://www.vwlowen.co.uk/internet/files.htm and possibly, but not essential, DMT - follow the links from this kitz page - http://www.kitz.co.uk/routers/ - to find out which version you need.
RouterStats is best for longer unattended monitoring. I suggest setting the sample rate to 8 seconds, 900 points per page (2 hrs). You need to set it to save the DS Noise Marhin and sync graphs always. If you'd like guidance on settings please ask.
mapletree
Grafter
Posts: 644
Registered: 28-07-2007

Re: Target SNR margin

Thanks ASBO & Anotherone for your help.  I'll keep my posts in this thread, as you suggested.
My 'better' router is a zyxel P660H and this works with Routerstats lite (not the full one AFAIK).  I have been monitoring the SNR margin all day.  I'm not sure how to get the error rates.  This info is not available via the web interface.  I don't believe either of my routers are supported by DMT tool.
The SNR margin fluctuates quite a bit in the range of 10-14dB.  It dropped to 7 once but recovered quickly.  I am not aware of anything internal that may have caused this.
Tomorrow I propose to swap routers and monitor it again, this time with the router right next to my master socket and see what happens.  I have to move a lot of things about for this so I have not done this before.
I have not noticed a downwards trend in SNR yet this evening.  Maybe this would happen later?  It's 5:15pm now.
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: Target SNR margin

mines not droping yet should do in the next hour tho
mapletree
Grafter
Posts: 644
Registered: 28-07-2007

Re: Target SNR margin

It's still hovering around the 11dB mark but with occasional spikes down to 8.
jack21
Grafter
Posts: 180
Registered: 25-02-2009

Re: Target SNR margin

Hi Mapletree,
You can use a utility called ZyxMon (you can find it via Google - its a freebee) to get the error details. Also, you can use telnet to get into the router's CLI and extract the details from there (not as simple as ZyxMon tho). Oddly enough, and I don't know why, the P-660-HW I have goes to SNRM 6.0 straight away, regardless of the in-use target SNRM. It gives a reasonable sync rate - not the best of the bunch, especially as it is at SNRM 6.0- but does give lowish error rates.
mapletree
Grafter
Posts: 644
Registered: 28-07-2007

Re: Target SNR margin

I have connected my other router (2700HGV) right by the master socket, eliminating my internal wiring.  Things look much better with a sync rate of 2300Kbps and a SNR margin of 13-14.  Therefore it looks like it is a problem with my internal wiring.  Oh dear, another job to do ;-)
scootie
Grafter
Posts: 4,799
Registered: 03-11-2007

Re: Target SNR margin

@ mapletree
take it you on the test socket behind the face plate on the master and not just plugged in to the master socket face plate?
mapletree
Grafter
Posts: 644
Registered: 28-07-2007

Re: Target SNR margin

I don't have a NTE5.  It's an old-style socket so there is only once place to plug in.
Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: Target SNR margin

Unfortunately with the older style master socket, plugging in there doesn't "eliminate" the internal wiring. How many extension sockets do you have? If you have a digital camera if you can provide a picture of your master socket, also carefully unscrew it and take a pic of the wiring going to the rear. If you can also post a couple of RouterStats Noise Margin graphs from day and mid-late evening.
You can attach these to your post using the additional options button below he reply window.
mapletree
Grafter
Posts: 644
Registered: 28-07-2007

Re: Target SNR margin

I don't have any extension sockets.  I have a really simple setup: one phone and one router plugged into the master socket via the microfilter.  The wiring I have eliminated is a long extension cable which goes to the back of the house where I have my computers & main router.
Community Veteran
Posts: 19,099
Thanks: 434
Fixes: 21
Registered: 31-08-2007

Re: Target SNR margin

Ah, OK forget the photos then. What sort of length cable are you talking about and what's it normally plugged into?
mapletree
Grafter
Posts: 644
Registered: 28-07-2007

Re: Target SNR margin

The extension cable is about 10m long and is plugged into a two-way adaptor in the master socket.  At the other end it goes straight into my router.  I know this is non-ideal and has been on my todo list for a long time.  However it worked acceptably well for a long time.  I checked this cable for obvious damage and could not find any.  However, I have reconnected today and I am only getting 1152Kbps :-(
mapletree
Grafter
Posts: 644
Registered: 28-07-2007

Re: Target SNR margin

I have ordered a new cable.  I hope it arrives soon since I am now at 384Kbps  Cry