Microfilters, get a good one

Hi All,

Just thought I'd share something with you. I've just successfully installed
an ethernet ADSL modem, but I'm part of the extended reach pilot scheme,
i.e. >5.5km and (supposedly) < 6km from the exchange. I installed the modem
as close as possible to the master phone socket and used a single
microfilter/splitter, the idea was to give the modem the cleanest and
strongest ADSL signal possible. I bought a cheap and unbranded microfilter
thinking all microfilters were the same - the result was no decent ringtone
on the normal phones and only a 3db SNR margin at the modem. I replaced the
microfilter with a BT approved (and much larger) version, and the result was
spectacular: Proper ring tones, no interference on the phones and a 20db SNR
margin at the modem!

Moral: Don't purchase a cheap microfilter. Throw away that freebee one
supplied with the modem, and buy a good quality BT approved version,
preferably one that meets BT's SIN346V2.2 specification. The good ones
apparently are physically large because they require large components to
meet the crosstalk isolation specs.

Mark.

"Peter Morgan - 0870 432 9631" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) .net...
> On 11 Aug 2003, "markp" <(E-Mail Removed)> wrote:
>
> >Throw away that freebee one supplied with the modem
>
> Sorry, but that seems a pretty daft idea... perhaps one should throw
> it (or put it on the shelf) *if* one has any problems with service.
>
> The "freebee" filters aren't necessarily below par. The ones which
> came with my Alcatel 'frog' were fine. The ones which came with a
> couple of Netgear DG814s were fine too. Depends on a case by case
> basis whether the filter is suitable. I have a variety of phones
> and caller displays but right now, most filters on my two lines
> only cost 1.25 +VAT from Ebuyer.

OK I didn't make it very clear, I was talking about those who are at the
limit of the reach and who need to guarantee a good signal at the modem. If
the microfilter supplied works for you then fine, however if it is not BT
approved or it does not state that it conforms with a certain spec then you
simply won't know how much your ADSL signal is being attenuated by the
filter - it may be good, it may not. As I said, the good ones are physically
large, the cheapo ones that are small simply cannot be good because the
components *have* to be large to meet the spec. If you have a high signal
strength to start with (i.e. not at the limits of the reach) then you'll
probably be OK with a substandard filter anyway, but those at the limit need
every db they can get!

Mark.

*OFF TOPIC*

Whist reading this I remember a friend was to far away to from the exchange
to get ADSL. How did you get involoved in the extended reach pilot scheme?


"markp" <(E-Mail Removed)> wrote in message
news:bhadaq$ve01t$(E-Mail Removed)...
>
> "Peter Morgan - 0870 432 9631" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) .net...
> > On 11 Aug 2003, "markp" <(E-Mail Removed)> wrote:
> >
> > >Throw away that freebee one supplied with the modem
> >
> > Sorry, but that seems a pretty daft idea... perhaps one should throw
> > it (or put it on the shelf) *if* one has any problems with service.
> >
> > The "freebee" filters aren't necessarily below par. The ones which
> > came with my Alcatel 'frog' were fine. The ones which came with a
> > couple of Netgear DG814s were fine too. Depends on a case by case
> > basis whether the filter is suitable. I have a variety of phones
> > and caller displays but right now, most filters on my two lines
> > only cost 1.25 +VAT from Ebuyer.
>
> OK I didn't make it very clear, I was talking about those who are at the
> limit of the reach and who need to guarantee a good signal at the modem.
If
> the microfilter supplied works for you then fine, however if it is not BT
> approved or it does not state that it conforms with a certain spec then
you
> simply won't know how much your ADSL signal is being attenuated by the
> filter - it may be good, it may not. As I said, the good ones are
physically
> large, the cheapo ones that are small simply cannot be good because the
> components *have* to be large to meet the spec. If you have a high signal
> strength to start with (i.e. not at the limits of the reach) then you'll
> probably be OK with a substandard filter anyway, but those at the limit
need
> every db they can get!
>
> Mark.
>
>

"Damo" <(E-Mail Removed)> wrote in message
news:bhan2u$oc1$(E-Mail Removed)...
> *OFF TOPIC*
>
> Whist reading this I remember a friend was to far away to from the
exchange
> to get ADSL. How did you get involoved in the extended reach pilot
scheme?
>
>

Apparently, according to
http://www.adslguide.org.uk/newsarchive.asp?item=1175 , many ISPs still
don't even know about this scheme! I suggest your friend contacts one of the
ISPs listed above and ask to be included, apparently BT are still allowing
subsriptions even though the places were supposed to be limited. The ISP
should email back within a few days as to the test results on the line, and
if favourable give an estimated date (usually around 10 days) as to when the
line will be enabled. I use Freedom2Surf (www.f2s.net) and they give good
service.

Mark.

"Peter Morgan - 0870 432 9631" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) .net...
> On 11 Aug 2003, "markp" <(E-Mail Removed)> wrote:
>
> >Throw away that freebee one supplied with the modem
>
> Sorry, but that seems a pretty daft idea... perhaps one should throw
> it (or put it on the shelf) *if* one has any problems with service.
>
> The "freebee" filters aren't necessarily below par. The ones which
> came with my Alcatel 'frog' were fine. The ones which came with a
> couple of Netgear DG814s were fine too. Depends on a case by case
> basis whether the filter is suitable. I have a variety of phones
> and caller displays but right now, most filters on my two lines
> only cost 1.25 +VAT from Ebuyer.

As a matter of interest, I saw in another post that you use a combination of
microfilters and an Excelsus Z420UK. Which one do you use for the ADSL
splitter? Was this the one supplied with the modem, or did you use that one
just for one of the phones and buy the Excelsus separately for the ADSL? I
use the Excelsus for my splitter, and it is far superior to another cheapo
version that I have, and much larger too (as it should be).

Mark.

In message <bhan2u$oc1$(E-Mail Removed)>
"Damo" <(E-Mail Removed)> wrote:

> *OFF TOPIC*
>
> Whist reading this I remember a friend was to far away to from the exchange
> to get ADSL. How did you get involoved in the extended reach pilot scheme?
>
>

I applied through Internet Central towards the end of July, even
though the web site gave a deadline of July 9th. I emailed them first
and they said they would try for me. My line was activated on August
1st and I'm happily using Broadband now. They have been very helpful
with keeping me informed and helping when I got stuck!

BTW neither Freeserve (was already on Anytime) nor Zen replied to
similar emails!

--
Keith Porter

On 12 Aug 2003 18:07, "markp" <(E-Mail Removed)> wrote:

> Which one do you use for the ADSL splitter? Was this the one supplied
> with the modem, or did you use that one just for one of the phones
> and buy the Excelsus separately for the ADSL?

At present, line #1 has an AR41 router connected, via a cheaper Ebuyer
or Dabs filter (sorry, I had 4 filters from Ebuyer but some have been
lent out, and until I have more than one of a kind, I'll be unable to
check those in use to know which is from Dabs and which from Ebuyer).
On line #1 at the master socket, there's a Sky digibox, a phone, and
an Easicom 200 caller display/hands free phone.

The Excelsus came with an Alcatel 'stingray'. It's on line #2 with
an AR11 router connected to it. I previously used it at the master
socket of line #1 just to filter the voice extensions, as the other
router (Dabsvalue) has a BT plug on it, and was in a socket doubler.

For sale:

Original NTE2000 adsl filters (the ones a bt engineers fits) the best that
money can buy 60% of BT call outs to self install jobs are due to shoddy
filters.

£4.99 + postage

"markp" <(E-Mail Removed)> wrote in message
news:bh92f1$vu5cu$(E-Mail Removed)...
> Hi All,
>
> Just thought I'd share something with you. I've just successfully
installed
> an ethernet ADSL modem, but I'm part of the extended reach pilot scheme,
> i.e. >5.5km and (supposedly) < 6km from the exchange. I installed the
modem
> as close as possible to the master phone socket and used a single
> microfilter/splitter, the idea was to give the modem the cleanest and
> strongest ADSL signal possible. I bought a cheap and unbranded microfilter
> thinking all microfilters were the same - the result was no decent
ringtone
> on the normal phones and only a 3db SNR margin at the modem. I replaced
the
> microfilter with a BT approved (and much larger) version, and the result
was
> spectacular: Proper ring tones, no interference on the phones and a 20db
SNR
> margin at the modem!
>
> Moral: Don't purchase a cheap microfilter. Throw away that freebee one
> supplied with the modem, and buy a good quality BT approved version,
> preferably one that meets BT's SIN346V2.2 specification. The good ones
> apparently are physically large because they require large components to
> meet the crosstalk isolation specs.
>
> Mark.
>
>

"Peter Morgan - 0870 432 9631" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) .net...
> On 12 Aug 2003 18:07, "markp" <(E-Mail Removed)> wrote:
>
> > Which one do you use for the ADSL splitter? Was this the one supplied
> > with the modem, or did you use that one just for one of the phones
> > and buy the Excelsus separately for the ADSL?
>
> At present, line #1 has an AR41 router connected, via a cheaper Ebuyer
> or Dabs filter (sorry, I had 4 filters from Ebuyer but some have been
> lent out, and until I have more than one of a kind, I'll be unable to
> check those in use to know which is from Dabs and which from Ebuyer).
> On line #1 at the master socket, there's a Sky digibox, a phone, and
> an Easicom 200 caller display/hands free phone.
>
> The Excelsus came with an Alcatel 'stingray'. It's on line #2 with
> an AR11 router connected to it. I previously used it at the master
> socket of line #1 just to filter the voice extensions, as the other
> router (Dabsvalue) has a BT plug on it, and was in a socket doubler.

Ah, good to see the frog came with a decent filter - this one has a spec
associated with it and is of the 'pigtail' variety rather than the plugin
type. Modify my suggestion then: Throw away those freebee unbranded plugin
types that do not have a spec! Also bundles that come from an ISP are more
likely IMO to come with a decent filter (such as the FreeUK bundle with frog
and Excelsus filters), after all it's the ISP who'll need to deal with
dis-satisfied customers first, not the modem manufacturer. A standalone
modem purchase could well have a cheap and nasty filter included to keep
costs down.

Mark.

> On Sat, 16 Aug 2003 11:55:35 +0100, "Lek" <(E-Mail Removed)> wrote:
>
> >>Proper ring tones, no interference on the phones and a 20db >>SNR
> >>margin at the modem!
> >> Mark.
> >>
>

"Chris" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> iI am new to the world of ADSL having waited for ever to get our local
> excahnge enabled only to find my line fails the line check on
> distance. I have applied for the extended range trial but do not hold
> out much hope.
>
> For my education, can you please tell me what is needed to measurew
> the SNR and what is the minimum one can work with?
>

The SNR margin I was quoting is measured by the modem itself, it has a web
page interface for configuration and shows both line attenuation and SNR
margin. This is after the line has been enabled for ADSL. The SNR figure is
a margin, i.e. 0dB SNR is where it would lose sync, and I have read modems
require something like 3-6dB SNR margin to sustain sync reliably. So how an
absolute SNR value is calculated and what constitutes an acceptable level I
couldn't tell you.

I would suggest making a fuss with your ISP if your line fails the extended
reach line test (your ISP should tell you in a week or so) as I don't
believe they'll tell you why, there's a possibility it is only just outside
the limits and some persuasion from the ISP might get BT to reconsider.

Mark.