Testing for RFI which may be causing intermittent broadband problem

I'm having frustrating ADSL problems (see below). Someone mentioned using a
MW radio to listen for interference, since ADSL uses similar frequencies. Is
there any particular frequency that I should tune the radio to? If
interference occurs, will it be reasonably obvious by listening?


The problem
-------------


My Netgear router contines to go into stupid mode intermittently:

- inability to browse or read email
- failure to do DNS domain->IP lookup
- can still ping external address by IP
- router still showing a connection; no information in log file
- downstream noice margin is all over the place (a constant 15 dB drops to
between 5 and 10 dB, changing every few seconds); no other parameters than
downstream margin change
- router's DSL light flickering furiously with no corresponding Ethernet or
wireless light activity
- does not cure itself spontaneously: need to unplug DSL lead for a few
seconds (or reboot router)

When it's working, router stats are typically

ADSL Link Downstream Upstream
Connection Speed 8128 kbps 448 kbps
Line Attenuation 5.0 db 2.5 db
Noise Margin 15.4 db 24.0 db

Voice reception is fine: no hiss, distortion or crackle.


Having eliminated DSL cable, microfilter, house wiring (I'm currently
plugged into the test socket via BT-to-RJ11 cable), I'm wondering what's
left. My ISP has done a test from their end and can't find any problem.

All this started suddenly a few days ago, having worked faultlessly for
three years. I'm not aware of anything in the house or with my computers
which has changed.

The problem always happens in the evening - after about 7PM and invariably
happens sometime while I'm asleep: every morning I wake up to find it in
silly mode. The interval between problems is very variable, ranging from 5
minutes to several hours between occurences. It's never happened between
0800 and 1900.

I have tested with my DECT phone base-station switched off at the mains (as
well as being unplugged from the phone line)

Either the router has started to fail or there's an intermittent DSL problem
or there's RFI from something.

By the way, would you expect the router to lose sync and then recover
spontaneously every time any other microfilter (even one with nothing
plugged into it) is plugged/unplugged? As I was unplugging or replugging
filters during my earlier testing, I noticed this symptom. It's different
from the stupid mode failure in that the DSL light actually goes out and
then flashes orange as it re-trains, rather than flickering green.

tune a mw radio into mw 612, best done with a portable or car radio, drive
past your house when you suspect the interference, you will get a loud hum
if radio/electrical is causing the problem,but then you have the problem of
, eg the interference is coming from a house 3 doors away, convincing them
they have something causing this, I have come across faulty wireless routers
and TV sets knocking out a whole row of houses, also something else to look
out for is garden lights that come on at dust.

Marky


"Mortimer" <(E-Mail Removed)> wrote in message
news:464e0140$0$8731$(E-Mail Removed)...
> I'm having frustrating ADSL problems (see below). Someone mentioned using
> a
> MW radio to listen for interference, since ADSL uses similar frequencies.
> Is
> there any particular frequency that I should tune the radio to? If
> interference occurs, will it be reasonably obvious by listening?
>
>
> The problem
> -------------
>
>
> My Netgear router contines to go into stupid mode intermittently:
>
> - inability to browse or read email
> - failure to do DNS domain->IP lookup
> - can still ping external address by IP
> - router still showing a connection; no information in log file
> - downstream noice margin is all over the place (a constant 15 dB drops to
> between 5 and 10 dB, changing every few seconds); no other parameters than
> downstream margin change
> - router's DSL light flickering furiously with no corresponding Ethernet
> or
> wireless light activity
> - does not cure itself spontaneously: need to unplug DSL lead for a few
> seconds (or reboot router)
>
> When it's working, router stats are typically
>
> ADSL Link Downstream Upstream
> Connection Speed 8128 kbps 448 kbps
> Line Attenuation 5.0 db 2.5 db
> Noise Margin 15.4 db 24.0 db
>
> Voice reception is fine: no hiss, distortion or crackle.
>
>
> Having eliminated DSL cable, microfilter, house wiring (I'm currently
> plugged into the test socket via BT-to-RJ11 cable), I'm wondering what's
> left. My ISP has done a test from their end and can't find any problem.
>
> All this started suddenly a few days ago, having worked faultlessly for
> three years. I'm not aware of anything in the house or with my computers
> which has changed.
>
> The problem always happens in the evening - after about 7PM and invariably
> happens sometime while I'm asleep: every morning I wake up to find it in
> silly mode. The interval between problems is very variable, ranging from 5
> minutes to several hours between occurences. It's never happened between
> 0800 and 1900.
>
> I have tested with my DECT phone base-station switched off at the mains
> (as
> well as being unplugged from the phone line)
>
> Either the router has started to fail or there's an intermittent DSL
> problem
> or there's RFI from something.
>
> By the way, would you expect the router to lose sync and then recover
> spontaneously every time any other microfilter (even one with nothing
> plugged into it) is plugged/unplugged? As I was unplugging or replugging
> filters during my earlier testing, I noticed this symptom. It's different
> from the stupid mode failure in that the DSL light actually goes out and
> then flashes orange as it re-trains, rather than flickering green.
>
>
>

marky wrote:

> also something else to look out for is garden lights that come on at dust.

Crappy inverters in them ?

Graham

"marky" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> tune a mw radio into mw 612, best done with a portable or car radio, drive
> past your house when you suspect the interference, you will get a loud hum
> if radio/electrical is causing the problem,but then you have the problem
> of , eg the interference is coming from a house 3 doors away, convincing
> them they have something causing this, I have come across faulty wireless
> routers and TV sets knocking out a whole row of houses, also something
> else to look out for is garden lights that come on at dust.

The problem has just happened - or rather it happened at about 4 AM but I've
just discovered it. So I put some batteries in my Walkman and waved it
around near the router. Near the router and the phone socket, there was a
lot of non-descript white noise. The only significant hum was from the PSU
in my printer, which gave a tone of a few hundred Hz in the radio.

I'll see if turning the printer off at the mains makes any difference to the
frequency of the problem.

As a matter of interest, how often in normal usage (when they isn't a
suspected line/router fault) would you expect a router to disconnect from
the internet and restart - the full "LCP is down / LCP is allowed to come up
/ CHAP authentication success" cycle. As long as I've had the router I've
noticed that occasionally (maybe every few months) the router log reports
this - and always in the period between 4AM and 6AM. Do BT and/or ISPs do
any sort of testing at around this time that might cause temporary
disconnections?

I ask because the router got into silly mode shortly after one of these this
morning: I can see the LCP and CHAP messages at 4:20 and the log file failed
to send by email at 5:00 so there must have been no WAN access by that time.
Then it successfully sent the 6:00 log and failed to send the 7:00 one,
corresponding with the router being locked up at 8:30.

A full disconnection involving LCP and CHAP messages is very rare: normally
the router locks without any helpful log messages.

On Sun, 20 May 2007 08:59:41 +0100, "Mortimer" <(E-Mail Removed)> mused:


>As a matter of interest, how often in normal usage (when they isn't a
>suspected line/router fault) would you expect a router to disconnect from
>the internet and restart - the full "LCP is down / LCP is allowed to come up
>/ CHAP authentication success" cycle. As long as I've had the router I've
>noticed that occasionally (maybe every few months) the router log reports
>this - and always in the period between 4AM and 6AM. Do BT and/or ISPs do
>any sort of testing at around this time that might cause temporary
>disconnections?
>
Depends, Bt do manintenance on lines\exchanges during the night,
usually without telling anyone as it's only minor. There's no set
frwquency to this.
--
Regards,
Stuart.