Re: Varying Noise Margin

Chris wrote:
> In article <4395e5be$0$1479$ed2619ec@xxxxxxxxxxxxxxxxxxxxxxxxxx>,
> Kraftee <kraftee@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> writes
>> Chris wrote:
>>> In article <4395ba92$0$1457$ed2619ec@xxxxxxxxxxxxxxxxxxxxxxxxxx>,
>>> Kraftee <kraftee@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> writes
>>>> Tiscali Tim wrote:
>>>>> In an earlier contribution to this discussion,
>>>>> Chris <nospam@[127.0.0.1]> wrote:
>>>>>
>>>>>> I have been getting occasional ADSL loss of synchronisation and
>>>>>> varying noise margin figures. I have tried everything I can
>>>>>> think of, including rewiring my extension with ethernet cable -
>>>>>> and I'm wondering if anyone can suggest anything else?
>>>>>>
>>>>>> Situation:
>>>>>> * 5 km from exchange
>>>>>> * Pipex
>>>>>> * Netgear DG834 version 2 latest firmware
>>>>>> * Line loss 49
>>>>>>
>>>>>> Noise margin is all over the place.
>>>>>> It doesn't seem to relate to anything in my house
>>>>>> (although there may be things I'm not yet aware of).
>>>>>> Sometimes connecting another computer to the router causes the
>>>>>> SNR to drop - but not always.
>>>>>>
>>>>>> It is usually between about 6 and 17.
>>>>>> (But why should it vary?)
>>>>>>
>>>>>> Sometimes the router loses synch continuously, dropping out and
>>>>>> re-connecting about once a minute. When this happens, rebooting
>>>>>> the router usually helps.
>>>>>>
>>>>>> BT have been very helpful and have given me the best available on
>>>>>> the E-side and on the D-side and my Line Loss has gone from 59 to
>>>>>> 49. Any ideas will be gratefully received and valued.
>>>>>
>>>>> Have you tried a different router and/or power supply for the
>>>>> router? I don't know whether the problem I had affects Netgear
>>>>> kit, but my
>>>>> 3Com router won't work reliably with the switch-mode power supply
>>>>> provided by 3Com - but is fine with a generic 3rd-party power
>>>>> supply. Have you got any other kit (e.g. laptop computer) using a
>>>>> switch-mode power supply, which could be injecting noise into the
>>>>> system?
>>>>
>>>> Have found that Netgear isn't to accurate for SNR readings (latest
>>>> firmware 3.01.5) so the OP maybe chasing ghosts there.
>>>
>>> My firmware is 3.01.25 ... just checked.
>>>
>>>> Have you (the
>>>> OP) tried removing the bell wire on the master/frontplate to see
>>>> what happens, generally your Loop attenuation will increase by a
>>>> couple of points but your SNR should be affected to a greater
>>>> extent to the positive, it should also be more stable as well. Even
>>>> though you may have wired it all in cat5 cable, it still
>>>> doesn't make any difference to the bell wire being unbalanced &
>>>> effectively it can become a long wire aeriel. You don't require
>>>> the bell wire as each filter will decouple the ringing, if it is
>>>> required by the phone at all
>>>
>>> I am getting results which confuse me.
>>> At first I connected to the MEP and got a really good SNR of 27.
>>> That was with mains powered laptop plugged into MEP.
>>>
>>> I left it on overnight and next morning it was 24 ... still good.
>>>
>>> Then, before I did my extension re-wiring, I checked again ... and
>>> got 15.
>>>
>>> That is an enormous difference!
>>>
>>> Then I re-did my extension wiring - about 90 feet - with cat5 cable
>>> - with 4 wires connected:
>>>
>>> PIN 2 - CAT5 cable White (blue)
>>> PIN 3 - CAT5 cable Orange (white)
>>> PIN 4 - CAT5 cable White (orange)
>>> PIN 5 - CAT5 cable Blue (white)
>>>
>>> Then I got - on the end of the extension - 22 - then 17 - 16 - 16
>>> ... Why should it be changing?
>>> This is not making sense!
>>> And why should it be better at the extension than at the MEP?
>>>
>>> Later I got 11.
>>>
>>> After a reboot of the router I got 17-16-16-16-17-17.
>>>
>>> Later I got 6-6-6-6-6-9-9-9-9.
>>>
>>> Later I got 12-12-12-12-12-12.
>>>
>>> This afternoon it was 14-14-14-14-14-14.
>>>
>>> Now it is 12-12-12-12-12.
>>>
>>> I am at a loss for hypotheses.
>>> Can you suggest what might be going on?
>>
>> Some of the Netgear routers (& 3Com for that matter) do display such
>> tendencies. With the 3Com it appears to have been pinned down to
>> fault prone power supplies & I wouldn't be suprised that it could be
>> that with the Netgear ones as well the only problem would be actualy
>> proving it as even with the latest firmware I still am apparently
>> rebooting around every 36-40 hours...
>> Think I'll stick with my Draytek ;-)
>
> Do you think that changing to a Draytek router might do the trick?
> I am prepared to do almost anything - although I don't want to waste
> money.
> Any recommendations for routers that cope well with long lines or the
> sort of varying SNR that I have been experiencing?

Arh, the Draytek 2600G displays completely different symptoms, it never
misses a beat, it never losses synch, but on the odd occasion when
something else on the network, could be the printer, NAS another PC is
turned on, for some reason I loose the network for around 30seconds. I
haven't been able to pin that one down yet. I've turned off the DHCP
function (needed to anyway as one machine lives in the DMZ) yet it still
happens, but for general usage I have never had a reboot or loss of
synch with mine.....

Anybody give me a hint I would be obliged...

I would still look to your internal network first before spending out
anymore money on another router which may, or may not, perform better
anyway.

Have you tried disconnecting the bell wire at the master socket, you
haven't got any of the cheap flat extension cables (or have you), the
extensions have been run in proper twisted pair not the cheaper alarm
wire (which is not only not twisted but is also stranded as well,
another possible cause of noise)..

The only reason I went & bought other routers to test with (& use as
spares when one goes faulty) is because it's my job to fault on the
blasted things so I made sure that my internal wiring was up to scratch
(& I've got to rewire yet again when the PC's are moved up into the loft
conversion next year).

It is unlikely, but not impossible that the problems originate on the
external wiring so you do have to check everything inside & then double
check. Heck it could even be a faulty filter...


.

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