Factory equipment interfering with router - advice?

Hi all,

At one of my customer's sites they have a Cisco 877 at the end of a fairly long BT line (6 or 7 KM we believe). The router itself is about 12 inches from where the line comes in.

In the factory (approximately 10 metres away, behind a brick wall) they use a shrink wrapper. When they fire up the shrink-wrapper, the SNR drops from 12.5 to between 6.0 and 7.5. Sometimes it drops lower and we lose sync...until we turn off the shrink wrapper. PRTG graphs show it leaping back up to 12.5 as soon as the guys knock off for the evening.

The wrapper is the size of a bus and can't be moved, and likewise the router is next to where the phone line enters the building.

We've tried different filters and different routers, and different RJ11 cables.

Any suggestions? Any way to physically shield the router?

Many thanks,



Jim

Edited by deleted (Thu 09-Sep-10 10:06:28)

Hi,

I've no idea if this will help but I had a problem on my line (or so I thought, it was actually two bad routers would you believe) and the engineer came out and fitted an RF filter right next to the master

Protecting the router may not solve the problem as the line could be picking up the noise too.

An RF filter may help but if the EMI (electro magnetic interference) is in band then it will not do much at all.

First move would be to get a sheet of cardboard about 1m square and cover in aluminium foil, attach an earth wire to the foil and then place the sheet between router and noise source. If that improves the SNR then use a sheet of steel or aluminium and paint it to blend in.

You could also build a small cage from chicken wire to go over the router - unsightly but can do the job.

Maybe consider an earthed sheet covering the wall on the factory side.

Get a mains filter - and plug the router power supply in to that as some noise could be on the power lines.

Do you have access to the incoming cable? Is it fitted to a wall? If so you could retrofit some capping under and over to form a screen fopr the last few metres.

Unfortunately we don't have access. There's a grey BT DP box on the wall, and the line is fed from that to the wall box (which isn't an NTE5 so we can't use an iPlate etc). I'll look into your suggestion, so many thanks for that. I'll also try ferrite rings, as sometimes they help and sometimes they don't.

I'll report back.

Cheers,


Jim

Many thanks. I've a few things to try now, and a BT RF filter (RF3?) will be investigated as well. I'll also contact the ISP to see if they have any advice..

Cheers,


Jim

I know it's mentioned briefly...

I use a Tacima Mains Conditioner - Searching on Amazon for 'Mains Conditioner' shows a few makes/models.
As they are fairly cheap it's worth a try!

Ofcom may be able to help. It is illegal to operate anything that causes interference. Ofcom have the powers to fine and/or close down such operators.

Try 'phoning Ofcom on 020 7211 0461 to explain the problem.

All the other advice posted is sound. A cage (Faraday Shield) may help and Ferite Rings too (wrap all cables to the router around a 25mm ring several times).

Good luck!