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uk.telecom.broadband (UK broadband) (uk.telecom.broadband) Discussion of broadband services, technology and equipment as provided in the UK. Discussions of specific services based on ADSL, cable modems or other broadband technology are also on-topic. Advertising is not allowed.

Does a Micro Filter do anything to the ADSL side??



 
 
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  #1  
Old January 30th 04, 07:38 PM posted to uk.telecom.broadband
Gareth Jones
external usenet poster
 
Posts: 85
Default Does a Micro Filter do anything to the ADSL side??

Hi Folks,

A strange thing happened today. My normally working fine ADSL connection
decided it couldn't sync to the exchange signal (we'd had a lightening
storm on Wed and had done something nasty to the BT system - it was only
fixed yesterday so I was rather suspicious that all of a sudden my
broadband had failed)
To cut a long story short, I was advised by my ISP (Demon) to try
another microfilter as they had run a test and it looked as if there was
no filtering happening. I said that it couldn't be that as I had tried
the modem 'straight through' with nothing else connected on the line -
the tec support person said I HAD to use a splitter.

I wasn't convinced as I thought that the microfilters were effectively
low pass filters for the voice side and I'm sure I've read you don't
need one if there is nothing else connected, and also, I've been using
it fine with the modem directly connected and just the phones connected
via the filters!

But whatever, I gave it a go....... and bugger me..... it now works!!

Can someone tell me what's going on??

--
__________________________________________________
Personal email for Gareth Jones can be sent to:
'usenet4gareth' followed by an at symbol
followed by 'uk2' followed by a dot
followed by 'net'
__________________________________________________
  #2  
Old January 30th 04, 07:42 PM posted to uk.telecom.broadband
PhilÅ
external usenet poster
 
Posts: 92
Default Does a Micro Filter do anything to the ADSL side??

No

A microfilter does nothing for the ADSL side, you don't need one.

The only thing a microfilter does is filter the DATA high pitched traffic
out for a voice line.




"Gareth Jones" wrote in message
...
Hi Folks,

A strange thing happened today. My normally working fine ADSL connection
decided it couldn't sync to the exchange signal (we'd had a lightening
storm on Wed and had done something nasty to the BT system - it was only
fixed yesterday so I was rather suspicious that all of a sudden my
broadband had failed)
To cut a long story short, I was advised by my ISP (Demon) to try
another microfilter as they had run a test and it looked as if there was
no filtering happening. I said that it couldn't be that as I had tried
the modem 'straight through' with nothing else connected on the line -
the tec support person said I HAD to use a splitter.

I wasn't convinced as I thought that the microfilters were effectively
low pass filters for the voice side and I'm sure I've read you don't
need one if there is nothing else connected, and also, I've been using
it fine with the modem directly connected and just the phones connected
via the filters!

But whatever, I gave it a go....... and bugger me..... it now works!!

Can someone tell me what's going on??

--
__________________________________________________
Personal email for Gareth Jones can be sent to:
'usenet4gareth' followed by an at symbol
followed by 'uk2' followed by a dot
followed by 'net'
__________________________________________________



  #3  
Old January 30th 04, 07:54 PM posted to uk.telecom.broadband
Phil Thompson
external usenet poster
 
Posts: 519
Default Does a Micro Filter do anything to the ADSL side??

On Fri, 30 Jan 2004 18:38:16 +0000, Gareth Jones
wrote:

Can someone tell me what's going on??


one possibility is that the filter was keeping some crap away from the
modem by filtering it - if a phone or some internal wiring is HF noisy
the low pass filter will keep that away from the ADSL modem, providing
the offending item is plugged into the voice side of the filter.

Is the experiment repeatable ? if you take the filter out of circuit
does it stop working.

Phil
  #4  
Old January 30th 04, 08:26 PM posted to uk.telecom.broadband
Gareth Jones
external usenet poster
 
Posts: 85
Default Does a Micro Filter do anything to the ADSL side??

In message , Phil Thompson
writes
one possibility is that the filter was keeping some crap away from the
modem by filtering it - if a phone or some internal wiring is HF noisy
the low pass filter will keep that away from the ADSL modem, providing
the offending item is plugged into the voice side of the filter.


But as I mentioned, I had tried it (two different modems in fact)
straight through with NOTHING else connected !!

--
__________________________________________________
Personal email for Gareth Jones can be sent to:
'usenet4gareth' followed by an at symbol
followed by 'uk2' followed by a dot
followed by 'net'
__________________________________________________
  #5  
Old January 30th 04, 11:38 PM posted to uk.telecom.broadband
BRG
external usenet poster
 
Posts: 56
Default Does a Micro Filter do anything to the ADSL side??

Gareth Jones wrote in
:

In message , Phil
Thompson writes
one possibility is that the filter was keeping some crap away
from the modem by filtering it - if a phone or some internal
wiring is HF noisy the low pass filter will keep that away from
the ADSL modem, providing the offending item is plugged into the
voice side of the filter.


But as I mentioned, I had tried it (two different modems in
fact) straight through with NOTHING else connected !!


I can't account for what you have observed, but I can add some
information on what splitters do in case that helps.

It is important for legacy analogue kit to be connected via a
splitter because:

1) The analogue kit may perform badly because of interference from
the high-frequency ADSL signal e.g. audible background noise on a
phone call.

2) The analogue kit can generate high-frequency noise, e.g. from
mechanical switches that disrupts the ADSL equipment.

Reason 2) is what many people don't appreciate. For example:
picking up the receiver for an incoming phone call may cause the
ADSL connection to drop if the phone is not connected via a
splitter.

In an ADSL splitter, the ADSL path is a straight-through electrical
circuit and it's only purpose for an ADSL modem is to provide a
RJ11 socket interface to the phone line.

--
BRG
===
http://www.brgservices.co.uk/
  #6  
Old January 31st 04, 12:29 AM posted to uk.telecom.broadband
Phil Thompson
external usenet poster
 
Posts: 519
Default Does a Micro Filter do anything to the ADSL side??

On Fri, 30 Jan 2004 19:26:33 +0000, Gareth Jones
wrote:

But as I mentioned, I had tried it (two different modems in fact)
straight through with NOTHING else connected !!


not knowing your system I wondered if there was extension wiring
connected that could be a problem - one guy could only get ADSL to
work straight off the master socket, reconnecting the extensions
(without anytihng plugged in) killed it off.

is it repeatable ie if you take the microfilter out now does it stop
working ?

how do you connect the modem without the microfilter - via an RJ11-BT
adaptor or how ? and does the microfilter have an RJ11 output for the
modem ?

Phil
  #7  
Old January 31st 04, 12:52 AM posted to uk.telecom.broadband
Ian
external usenet poster
 
Posts: 37
Default Does a Micro Filter do anything to the ADSL side??

Gareth Jones wrote in message ...
In message , Phil Thompson
writes
one possibility is that the filter was keeping some crap away from the
modem by filtering it - if a phone or some internal wiring is HF noisy
the low pass filter will keep that away from the ADSL modem, providing
the offending item is plugged into the voice side of the filter.


But as I mentioned, I had tried it (two different modems in fact)
straight through with NOTHING else connected !!


Firstly Lightning does very strange things to circiuts, and very often
the componants take a few days to break down.
As to you problem, you say it works fine with no filter. but with a
filter it doesnt. Is this all filters or just one.
For your modem you dont need and to be honest shouldnt use a filter if
at all possible. for phones you will need a filter. It sounds as if
the filters go a bit of a spike and are no kaput.

Plug your modem in on its own if alls well add 1 filter at a time, if
it stops working that is the offending filter, if its still working
plug 1 phone in at a time etc.

Ian

www.cyber-cottage.co.uk
  #8  
Old January 31st 04, 12:52 AM posted to uk.telecom.broadband
Ian
external usenet poster
 
Posts: 37
Default Does a Micro Filter do anything to the ADSL side??

Gareth Jones wrote in message ...
In message , Phil Thompson
writes
one possibility is that the filter was keeping some crap away from the
modem by filtering it - if a phone or some internal wiring is HF noisy
the low pass filter will keep that away from the ADSL modem, providing
the offending item is plugged into the voice side of the filter.


But as I mentioned, I had tried it (two different modems in fact)
straight through with NOTHING else connected !!


Firstly Lightning does very strange things to circiuts, and very often
the componants take a few days to break down.
As to you problem, you say it works fine with no filter. but with a
filter it doesnt. Is this all filters or just one.
For your modem you dont need and to be honest shouldnt use a filter if
at all possible. for phones you will need a filter. It sounds as if
the filters go a bit of a spike and are no kaput.

Plug your modem in on its own if alls well add 1 filter at a time, if
it stops working that is the offending filter, if its still working
plug 1 phone in at a time etc.

Ian

www.cyber-cottage.co.uk
  #9  
Old January 31st 04, 10:52 AM posted to uk.telecom.broadband
Phil Thompson
external usenet poster
 
Posts: 519
Default Does a Micro Filter do anything to the ADSL side??

On 31 Jan 2004 08:57:27 GMT, Brian McIlwrath
wrote:

The microfilters DO have an RJ11 output for the modem. As you suggest a
simple BT-RJ11 convertor will work just as well.


I was wondering how the OP's "direct" connection was made. His modem
might have a BT plug but in either case there's an adaptor in there
that may be an issue itself.

Phil
  #10  
Old January 31st 04, 11:23 AM posted to uk.telecom.broadband
Gareth Jones
external usenet poster
 
Posts: 85
Default Does a Micro Filter do anything to the ADSL side??

In message , Phil Thompson
writes
The microfilters DO have an RJ11 output for the modem. As you suggest a
simple BT-RJ11 convertor will work just as well.


I was wondering how the OP's "direct" connection was made. His modem
might have a BT plug but in either case there's an adaptor in there
that may be an issue itself.


Ok, some confusion here from some (other) posters, so I'll try to
clarify:

I had a standard extension lead going straight from the master socket to
the ADSL modem via a BT RJ11 lead. Nothing else in the property
connected. Worked fine.
So I know the ADSL modem can work 'straight through'

I then put a couple of normal t-piece splitters (no filters) in the
system and used a microfilter wherever a phone was to be connected - the
modem is thus still 'straight through'
Worked fine.
(I'm on the limit of distance so was getting steady 59db attenuation -
measured by two modems I have and the BT PTO!)

After an electrical storm, BT had to do some repairs, the phone was OS
for a day.
When it came back, my attenuation figures are wandering around - but now
in the low sixties - but the modem was still working fine.

Then the modem connect light went off and could not reconnect (with
either of my two modems)
I disconnected _everything_ except the modem - still nothing.
I stick a microfilter on the end, and connect the modem via the correct
RJ11 connector on it - voila! The bloody thing start to work!?!

So the microfilter must be doing _something_ - I'm just curious as to
what??

If its true that the ADSL port of the microfilter is indeed a straight
pass through, The only theory I can come up with myself at the moment is
that BT have changed something, my line is now operating on the limit
(its 61.1 db and 9.4 SNR as I write) and yesterday, it drifted out of
spec and stopped working (I had seen 64db in the morning)
Maybe putting the microfilter on was enough to change the
characteristics of the line (via the tapped low pass filter) to just
bring it back into operating range???

???
--
__________________________________________________
Personal email for Gareth Jones can be sent to:
'usenet4gareth' followed by an at symbol
followed by 'uk2' followed by a dot
followed by 'net'
__________________________________________________
 




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