ADSL Filters

Just had an Openreach engineer round. He was testing the downstream speed
at my main socket and reckoned it was low. For some reason he asked if he
could use my filter and replaced his bog standard BT one with it. Up the
synch rate went by almost 800 kbps, so they are important bits of kit
aren't they? I wonder if his BT one was faulty or is that speed difference
indicative of the difference in filter quality. Mine are supposed to be 5
star rated.
--
Heard melodies are sweet, but those Unheard are sweeter
(E-Mail Removed) FN 2°°9 +, Mungo Brandybuck of Buckland

Ato_Zee wrote:
>> Just had an Openreach engineer round. He was testing the downstream
>> speed at my main socket and reckoned it was low. For some reason he
>> asked if he could use my filter and replaced his bog standard BT one
>> with it. Up the synch rate went by almost 800 kbps, so they are
>> important bits of kit aren't they? I wonder if his BT one was faulty or
>> is that speed difference
>> indicative of the difference in filter quality. Mine are supposed to be
>> 5 star rated.
>
> Disconnecting (breaking the link) either by unplugging or power
> off/on can result in reconnecting at a different synch speed. A
> difference of 800 kbps relative to what?
> Unplugging, and reconnecting again, might have got you back to
> where you were before.
> There is a spec for filters SIN346
> http://www1.btwebworld.com/sinet/346v2p7.pdf
> and the filters you buy should comply, including
> CE (Chinese Export) ones.
> I have found you can chain two or more, but there is
> no advantage in more than two, PROVIDED you
> plug your modem into the first, and phones into
> the last in the chain.
> Such multi-stage filtering does not affect voice
> quality, or operation of CLSID units, mine still
> announces who the caller is, and displays name
> and number.
> So worth trying two cheap filters before forking out
> for a reputed better performing one, which may
> turn out to be Snake Oil advertising blurb.
> Modem/routers do differ in performance
> and synch speed, in some cases by much
> more than your quoted 800 kbps.
> .
We are talking about a broadband engineer plugging his standard test
equipment into the test socket using his dsl filter. With his filter he was
reading around 6100 kbps. Replacing his filter with the one I used he read
6848 kbps. As he couldn't believe the reading he put his filter back in and
checked again to get the lower reading once more. Coincidentally, my
router a 10 metre extension lead away subsequently is now synching at 6848
kbps.


--
Heard melodies are sweet, but those Unheard are sweeter
(E-Mail Removed) FN 2°°9 +, Mungo Brandybuck of Buckland

In an earlier contribution to this discussion,
Flyiñg Ñuñ 2°°9 + on netbook <(E-Mail Removed)> wrote:

>> .
> We are talking about a broadband engineer plugging his standard test
> equipment into the test socket using his dsl filter. With his filter
> he was reading around 6100 kbps. Replacing his filter with the one I
> used he read 6848 kbps. As he couldn't believe the reading he put
> his filter back in and checked again to get the lower reading once
> more. Coincidentally, my router a 10 metre extension lead away
> subsequently is now synching at 6848 kbps.

Did he measure it without *any* filter? When using the test socket there's
no need for a filter since all the analog wiring is disconnected anyway -
unless you plug the faceplate into the filter's phone socket - but why would
you do *that*?

If just using the filter as a BT to RJ11 adapter, the digital connection
should be straight through and the filter shouldn't actually do anything -
so it's difficult to see why one should be any different from another.
--
Cheers,
Roger
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Roger Mills wrote:
> In an earlier contribution to this discussion,
> Flyiñg Ñuñ 2°°9 + on netbook <(E-Mail Removed)> wrote:
>
>>> .
>> We are talking about a broadband engineer plugging his standard test
>> equipment into the test socket using his dsl filter. With his filter
>> he was reading around 6100 kbps. Replacing his filter with the one I
>> used he read 6848 kbps. As he couldn't believe the reading he put
>> his filter back in and checked again to get the lower reading once
>> more. Coincidentally, my router a 10 metre extension lead away
>> subsequently is now synching at 6848 kbps.
>
> Did he measure it without *any* filter? When using the test socket there's
> no need for a filter since all the analog wiring is disconnected anyway -
> unless you plug the faceplate into the filter's phone socket - but why
> would you do *that*?
>
> If just using the filter as a BT to RJ11 adapter, the digital connection
> should be straight through and the filter shouldn't actually do anything -
> so it's difficult to see why one should be any different from another.

It looked like he was doing the latter to me.
--
Heard melodies are sweet, but those Unheard are sweeter
(E-Mail Removed) FN 2°°9 +, Mungo Brandybuck of Buckland

On Thu, 13 Aug 2009 16:09:12 UTC, "Pete Zahut" <dont@bother> wrote:

> If you mean something with the CE mark, it definitely does _not_ mean
> Chinese Export:

W hooosh!

--
[ 7'ism - a condition by which the sufferer experiences an inability
to give concise answers, express reasoned argument or opinion.
Usually accompanied by silly noises and gestures - incurable, early
euthanasia recommended. ]

On Thu, 13 Aug 2009 21:06:27 UTC, "Pete Zahut" <dont@bother> wrote:

> Bob Eager wrote:
> > On Thu, 13 Aug 2009 16:09:12 UTC, "Pete Zahut" <dont@bother> wrote:
> >
> >> If you mean something with the CE mark, it definitely does _not_ mean
> >> Chinese Export:
> >
> > W hooosh!
>
> ??????

The sound of the joke passing over your head! :-)

--
[ 7'ism - a condition by which the sufferer experiences an inability
to give concise answers, express reasoned argument or opinion.
Usually accompanied by silly noises and gestures - incurable, early
euthanasia recommended. ]

> I have found you can chain two or more, but there is
> no advantage in more than two, PROVIDED you
> plug your modem into the first, and phones into
> the last in the chain.

You would indeed need to plug the phones into the
last one to take advantage of the tandem filters
but there is no real difference in which you use for
the modem apart from the possibility of an unnecessary
pair of potentially noisy contacts.


--
Graham.

%Profound_observation%

Peter Crosland wrote:
> "Roger Mills" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> In an earlier contribution to this discussion,
>> Flyiñg Ñuñ 2°°9 + on netbook <(E-Mail Removed)> wrote:
>>
>>>> .
>>> We are talking about a broadband engineer plugging his standard test
>>> equipment into the test socket using his dsl filter. With his filter
>>> he was reading around 6100 kbps. Replacing his filter with the one I
>>> used he read 6848 kbps. As he couldn't believe the reading he put
>>> his filter back in and checked again to get the lower reading once
>>> more. Coincidentally, my router a 10 metre extension lead away
>>> subsequently is now synching at 6848 kbps.
>> Did he measure it without *any* filter? When using the test socket there's
>> no need for a filter since all the analog wiring is disconnected anyway -
>> unless you plug the faceplate into the filter's phone socket - but why
>> would you do *that*?
>>
>> If just using the filter as a BT to RJ11 adapter, the digital connection
>> should be straight through and the filter shouldn't actually do anything -
>> so it's difficult to see why one should be any different from another.
>
>
> Without getting too technical adding any form of filter network to a phone
> line will alter the characteristics of the line. This effect may be anything
> from very small to very large. This topic has been discussed at length in
> the past and lots of disparate views were expressed many of them
> nonsensical. The real difficulty with trying to establish the quality of
> ADSL filters using just a modem is that the line's characteristics are
> changing all the time and in particular are affected by the BT profiling
> system. Hence any results using this method can b e very misleading. This
> link tells you quite a lot about ADSL filters
>
> http://www.adslnation.com/support/filters.php
>
> Whilst this tells you more about filter theory
>
> http://en.wikipedia.org/wiki/Low-pass_filter
>
> Peter Crosland
>
>
There is another matter to consider..corrosion on contacts. If Mr BT is
using the same filter day in and day out, he's probably got a load of
naff shit on it. I mean he's plugged it into everyone's orifice. You
dunno WHERE its been..

The Natural Philosopher wrote:
> Peter Crosland wrote:
>> "Roger Mills" <(E-Mail Removed)> wrote in message
>> news:(E-Mail Removed)...
>>> In an earlier contribution to this discussion,
>>> Flyiñg Ñuñ 2°°9 + on netbook <(E-Mail Removed)> wrote:
>>>
>>>>> .
>>>> We are talking about a broadband engineer plugging his standard
>>>> test equipment into the test socket using his dsl filter. With
>>>> his filter he was reading around 6100 kbps. Replacing his filter
>>>> with the one I used he read 6848 kbps. As he couldn't believe the
>>>> reading he put his filter back in and checked again to get the
>>>> lower reading once more. Coincidentally, my router a 10 metre
>>>> extension lead away subsequently is now synching at 6848 kbps.
>>> Did he measure it without *any* filter? When using the test socket
>>> there's no need for a filter since all the analog wiring is
>>> disconnected anyway - unless you plug the faceplate into the
>>> filter's phone socket - but why would you do *that*?
>>>
>>> If just using the filter as a BT to RJ11 adapter, the digital
>>> connection should be straight through and the filter shouldn't
>>> actually do anything - so it's difficult to see why one should be
>>> any different from another.
>>
>>
>> Without getting too technical adding any form of filter network to a
>> phone line will alter the characteristics of the line. This effect
>> may be anything from very small to very large. This topic has been
>> discussed at length in the past and lots of disparate views were
>> expressed many of them nonsensical. The real difficulty with trying
>> to establish the quality of ADSL filters using just a modem is that
>> the line's characteristics are changing all the time and in
>> particular are affected by the BT profiling system. Hence any
>> results using this method can b e very misleading. This link tells
>> you quite a lot about ADSL filters
>> http://www.adslnation.com/support/filters.php
>>
>> Whilst this tells you more about filter theory
>>
>> http://en.wikipedia.org/wiki/Low-pass_filter
>>
>> Peter Crosland
>>
>>
> There is another matter to consider..corrosion on contacts. If Mr BT
> is using the same filter day in and day out, he's probably got a load
> of naff shit on it. I mean he's plugged it into everyone's orifice.
> You dunno WHERE its been..

Conversely, you'd think that constant removal and insertion could clean the
contacts.
--
Heard melodies are sweet, but those Unheard are sweeter
(E-Mail Removed) FN 2°°9 +, Mungo Brandybuck of Buckland

Flyiñg Ñuñ 2°°9 + wrote:
> The Natural Philosopher wrote:
>> Peter Crosland wrote:
>>> "Roger Mills" <(E-Mail Removed)> wrote in message
>>> news:(E-Mail Removed)...
>>>> In an earlier contribution to this discussion,
>>>> Flyiñg Ñuñ 2°°9 + on netbook <(E-Mail Removed)> wrote:
>>>>
>>>>>> .
>>>>> We are talking about a broadband engineer plugging his standard
>>>>> test equipment into the test socket using his dsl filter. With
>>>>> his filter he was reading around 6100 kbps. Replacing his filter
>>>>> with the one I used he read 6848 kbps. As he couldn't believe the
>>>>> reading he put his filter back in and checked again to get the
>>>>> lower reading once more. Coincidentally, my router a 10 metre
>>>>> extension lead away subsequently is now synching at 6848 kbps.
>>>> Did he measure it without *any* filter? When using the test socket
>>>> there's no need for a filter since all the analog wiring is
>>>> disconnected anyway - unless you plug the faceplate into the
>>>> filter's phone socket - but why would you do *that*?
>>>>
>>>> If just using the filter as a BT to RJ11 adapter, the digital
>>>> connection should be straight through and the filter shouldn't
>>>> actually do anything - so it's difficult to see why one should be
>>>> any different from another.
>>>
>>> Without getting too technical adding any form of filter network to a
>>> phone line will alter the characteristics of the line. This effect
>>> may be anything from very small to very large. This topic has been
>>> discussed at length in the past and lots of disparate views were
>>> expressed many of them nonsensical. The real difficulty with trying
>>> to establish the quality of ADSL filters using just a modem is that
>>> the line's characteristics are changing all the time and in
>>> particular are affected by the BT profiling system. Hence any
>>> results using this method can b e very misleading. This link tells
>>> you quite a lot about ADSL filters
>>> http://www.adslnation.com/support/filters.php
>>>
>>> Whilst this tells you more about filter theory
>>>
>>> http://en.wikipedia.org/wiki/Low-pass_filter
>>>
>>> Peter Crosland
>>>
>>>
>> There is another matter to consider..corrosion on contacts. If Mr BT
>> is using the same filter day in and day out, he's probably got a load
>> of naff shit on it. I mean he's plugged it into everyone's orifice.
>> You dunno WHERE its been..
>
> Conversely, you'd think that constant removal and insertion could clean the
> contacts.
No. I found this out many years ago on a test rig.

Once the plating wears through, there is a rapid build up of oxides on
the substrate. Most BT style contacts are gold plated phosphor bronze:
You will end up with a nice rectifying layer of copper oxide and
possibly one or to others if the plating goes.