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[guest]

@ ANYONE - can anybody tell me the difference between passive (capacitor) and active (transistor) filters..? ive heard active ones arent as good or can fail quicker yet ADSLnation say that their filters are better than Pressac filters, well they rate theirs 5/5 and pressac 4.5/5

There was a discussion here last spring/summer about this - have a search for it.

Basically the ADSLNation filters have the internal phone wiring electrically disconnected from the line until either a call is received or the phone is off-hook. At that point they switch in a fairly standard filter.

[sheddyian]

I did a quick test of an ADSL Nation filtered faceplate and a standard BT SSL.

Comparing line attenuation, synch speed and noise margin on my admittedly fairly short and reliable line with ADSL2+, I couldn't see any difference in performance between them.

If you visit the ADSL Nation site it might surprise you to find they are now owned by Tandy.

Who still exist!

Ian

[snadge]

THANKS for replies guys... so the active part is what cuts off the internal wiring, on BT;s its always connected with a 'passive' filter removing them... wonder just how good the passive filter IS for removing noise...shame we didnt have a noisey internal wiring installation we could test them both on lol

[guest]

The filters are all much of a muchness. ie pretty much the same design.

Not exactly a hard job to do really, its just a simple low-pass filter and the same design has worked fine here for 13 years.

The problem is wiring, not filters and with the best will in the world a couple of filters are unlikely to deal with the rats nest of wiring which the average 50 year old house has.

One master socket, DECT phones, CAT5 wiring for networking. Surprisingly cheap to do - even if you pay a sparky to route the CAT5 - but people would rather bugger around with homeplugs and extensions all over the damn place.

Oh and yes I appreciate most people don't understand any of this - they don't understand their car either but they still pay the service monkeys to read the diagnostics and change what bits the computer tells them to. They are unwilling to do the same when it comes to BB* (or computers in general) so I have little sympathy.

*my mother-in-law is just the same, although she has no real excuse as she has a physics degree. Last house she was in had crap sync because of flat cable extensions (self-installed of course  ) and this one has star wiring. Life is too short to get involved - I explained it all to her years ago and she shrugged it off as "nonsense"

[snadge]

Lol @ mother in law...

Still,  no sympathy aside, it'd be great to know which is best at removing the signal/noise from extension wires...  Can low pass and active filters stop emi, power surges or other such problems that can wreak havoc on adsl?

Also I guess that the active filter allows any discrepancies back into the line when an extension phone rings which could cause problems with the adsl signal?

 I wonder if a  faceplate with both on would be superior? Active to remove it entirely and passive for when calls are made to extension phone for extra protection?!

Sent from my Sony Xperia Miro on Tapatalk

[guest]

The filter is  low-pass (<30kHz IIRC). It will have very high insertion loss (attenuation) on frequencies above that on the phone port of the filter.

The important part is WHERE the filter is fitted.

If you are trying to sort out your own (minor) problems then forget it. IIRC you're in flats with an external run of cable along the flats? The noise is present BEFORE it hits your NTE and hence there is bugger all chance of a filter after the NTE doing anything

ADSL is unfiltered; phones are filtered.

Oh and the "active filter" is a couple of trannies and a couple of relays. ie its not a filter at all, it is a switch. Switch is off = no voice call; switch is on = voice call + inline filter. It doesn't switch the bellwire out though IIRC (which I may not).

Best bet is to read the thread from last year really, I don't think any of us want to rehash that 

Edit - also what any electronics engineer would understand by "active filter" is that its likely to involve an op amp and feedback if you are using discrete components. That sort of filter is more than likely going to be a notch filter (couple of kHz maximum), whereas the ADSLNation "active filter" simply connects the filtered section when required. The filter is the same as the rest of them.

Edit2 - yes you could build a better (more poles) filter. Why bother though as the standard filter is fine - you measure either side of it and it'll be spot on, however the wiring in between that filter and the router may be getting all sorts of crap on it.

[guest]

http://forum.kitz.co.uk/index.php/topic,11277.0.html

Thats the thread last year snadge. Probably 

Edit - also do NOT necro it on pain of death 

[snadge]

@ Rizla - sorry for my lack of knowledge .. do you mean dont revive the thread? lol

so the ADSLnation does have a filter when its 'connected' for calls? - this isnt for my problems (i dont have any internal problems) just trying to determine which one would be the best, from the sounds of it the ADSLnation one would be the best if it does indeed filter when it connects the internal wiring for incoming calls, if not then I would rather advise people to get a passive one..?

i emailed BT about the SIN's not mentioning VDSL, they sent my question to the 'Product Manager for SIN346' and this was their reply,...

...."SIN346 is specific to ADSL. VDSL relates to our Fibre to the Cabinet product. Information on this product can be found in SINs 472, 495 and 498."

http://www.sinet.bt.com/472v2p4.pdf

http://www.sinet.bt.com/495v1p0.pdf

http://www.sinet.bt.com/498v4p3.pdf

at a quick glance they seem to be more about the products rather than filters? maybe im wrong

[thomasjc1]

i snipped out the surge arrestor today aint noticed any difference

[snadge]

i snipped out the surge arrestor today aint noticed any difference

i doubt it would in your case as you already have the max speed so you cant go any higher, also, for most people I would imagine the change wouldnt be immediate, DLM can take a week or so to react to better line conditions (if it even bothers too!!)

[thomasjc1]

To be honest i didnt expect it to do anything for me but i thought i would try

[burakkucat]

From SIN 498 Issue 4.3 --

 . . .

3.2.6 CPE VDSL2 Filter Requirements

In order to ensure correct operation with the BT VDSL2 and PSTN networks, CPE
VDSL2 filter devices intended for connection to BT GEA-FTTC lines shall meet one
of two alternative sets of recommendations:

R.FILTER.1 Centralised splitters shall comply with the requirements of ETSI
Specification TS 101 952-1[16] as set out in Section 3.2.6.1.

R.FILTER.2 Distributed splitters shall comply with the requirements of ETSI
Specification TS 101 952-3[17] as set out in Section 3.2.6.2

3.2.6.1 Centralised CPE VDSL2 filter device requirements
In this case the filter shall be compliant with TS 101 952-1[16] with the following
options selected:

i) Option B category of Section 6 of TS 101 952-1.
ii) The option to support metering pulses as described in section 6.7 of TS 101
   952-1 does not need to be implemented.
iii) The option to provide common mode rejection as described in section 6.14 of
    TS 101 952-1 does not need to be implemented, although it is known that this
   option can help to improve DSL service reliability.
iv) The applicable tables in Normative Annex A of TS 101 952-1 for VDSL2
   filters are
  • Table A.2 (Dedicated requirements for splitters for xDSL system
   variants),
  • Table A.3 (Differentiation of IL in the xDSL band between LE and TE
   side),
  • Table A.6 (Dedicated frequency ranges for splitters for VDSL2 system
   variants) and
  • Table A.9 (Dedicated requirements for passive splitters for VDSL2
   over POTS variants at the TE side).

3.2.6.2 Distributed CPE VDSL2 filter device requirements
In this case the filter shall be compliant with TS 101 952-3[17] with the following
options selected:

i) Option B category of section 6 of TS 101 952-3.
ii) The option to support metering pulses as described in section 6.7 of TS 101
   952-3 does not need to be implemented.
iii) The applicable tables in Normative Annex A of TS 101 952-3 for VDSL2
    filters are
• Table A.2 (Dedicated requirements for distributed filters for xDSL
   system variants),
• Table A.3 (Overview of all POTS band requirements for all types of
   filters and N values),
• Table A.4 (Overview of Insertion Loss in the xDSL band for all types
   of filters
• Table A.7 (Dedicated frequency ranges for distributed filters for
   VDSL2 system variants).
Where appropriate, the requirements for either the “Standard” filter class (see
Section 6.1.1 of TS 101 952-3) with N=3 or the “Enhanced” filter class with
N=4 shall be selected from the appropriate column in the tables (N is the
minimal number of parallel filters in the test setup - see Section 6.4.1 of TS
101 952-3).
iv) If the CPE VDSL2 filter is to be used in a multiple filter topology then the
filter shall pass the recommendations of TS 101 952-3 with up to two other
CPE VDSL2 filters (Standard) or three CPE VDSL2 filters (Enhanced)
connected in parallel with the CPE VDSL2 filter under test. Each filter shall
have their Telephony Port open circuit.

3.2.6.3 Additional notes about CPE filters
The standard BT PSTN CPE interface is a 3 wire circuit (A-line, B-line and bell wire)
whereby the bell wire is AC-coupled from the B-line. This bell wire must either be
filtered by the filter or left open circuit at the Line Port and recreated at the Telephony
Port of the filter. This may be achieved using a 1.8 μF capacitor between the B line
(pin 5) and the bell wire (pin 4) at the Telephony Port.
It should be noted that during normal operation of BT PSTN services switching may
occur between line states such as line feed, reversed line feed, ringing and dialling
(loop disconnect or tone). These changes of state may be associated with large
transient voltage excursions. The performance of data circuits operating from the
VDSL2 Port under these conditions is a function of the data modem internal
performance. This and other factors may be a cause for specifications outside the
scope of this document.
The A-line and B-line may be disconnected, shorted together, taken to earth or
connected to standard network conditions (Voltages up to -95 V, PSTN conditions,
ringing etc) at any point in the system. No maintenance intervention should be
required after such an event to restore normal modem operation.

 . . .

[16] http://www.etsi.org/deliver/etsi_ts/101900_101999/10195201/01.01.01_60/ts_10195201v010101p.pdf
[17] http://www.etsi.org/deliver/etsi_ts/101900_101999/10195203/01.01.01_60/ts_10195203v010101p.pdf

The two references, [16] & [17] above, define the requirements of the centralised and distributed filters for the Beattie VDSL2 service.

[snadge]

Thanks bk

Sent from my Sony Xperia Miro on Tapatalk

[ColinS]

Couldn't have put it better myself B*K! Meow! 

http://forum.kitz.co.uk/index.php/topic,12520.15.html @ post 27!

[burakkucat]

Couldn't have put it better myself B*K! Meow! 

http://forum.kitz.co.uk/index.php/topic,12520.15.html @ post 27!