All an NTE2000, an NTE2005 or a SSFP does is to apply low-pass, high-block filtering to the telephony socket. If no telephones will ever be connected, then the filtering is actually redundant! ::)
The (VDSL) SSFP does also do the following, which other faceplates may or may not do:
1) Isolates any extension wiring, i.e. prevents you from running it with dongles elsewhere. This may or may not be a good thing depending upon the state of your internal wiring.
2) it brings the VDSL signal onto punchdowns so that you can run a cat5e cable as a 'data extension'
3) makes the entire NTE twice the *~! size it previously was, thereby making it even more ugly and more likely to be knocked. ::)
AIUI, more recent BTOR NTE5's allegedly have both the bell-wire disconnect and REIN filter included. The SFI who resolved the lateral inbalance on my line last year fitted one as a matter of course 'in preparation for fibre' for that reason.
BTOR have already announced forthcoming Q3? changes to Fibre install whereby the ISP can provide the EU with either an SSFP or dongles along with their own CPE e.g. a combined VDSL modem/router
If I'm reading your post correctly, by 'Punchdowns' I'm assuming you mean IDC terminations (Insulation Displacement Connectors). More commonly referred to as 'Krone' connections ??Yes, I did. :)
If so, I thought it worth pointing out that in time gone by, if the EU required a data-extention socket in another room to that of the NTE5, as this would be better suited for the router, we were told to use these terminations to carry the VDSL signal to the extention socket.Yes, perfect sense, although personally I think that 'them above' have got a bit of a cheek really, as (to me at least) the whole point of a BTOR installed 'data extension' (as originally conceived) was indeed to move the demarcation point!!!!! Anyway with dongles mode shortly to be 'approved', what care I? ;) :)
However, a rethink by 'them above' means if the same scenario is required, we have to run a 'Cat cable' from the plug-in port on the face-plate to where the socket is to be sited. The reason being, the demarcation point was breached if fed via the 'Krone' terminations, and therefore OR became liable for the new extention lead as well. With the later 'Plug-in' extention, the EU can still test at the NTE whether he has a connection or not, should a fault develop on his circuit ?? Hope this waffle makes sense ?? :)
PS ......... we were told that the NTE2000 and indeed the VDSL plates do have additional REIN/RFI protection built in to them. I can't prove this to be true (unlike Asbo or B*Cat), but I can say that before a REIN/RFI interference case is raised by our technical team, a NTE2000/VDSL plate HAS to have been fitted alongside an RF3 filter, before the case will be raised. Not advocating the practice, just saying that 'Thems the rules'. ;) :)I can 'understand' why they might say that, but AFAIK it is an RF3 equivalent that is already in the faceplate ::) (and I think I have seen some evidence, if not proof, of that) - I think we discussed this privately at the time, as then at least, there was some difference in practise between OR mainland and your good selves. Of course the only right thing to do is 'always' to follow the rules! ;) ;D
Does anyone else remember the original (pre-1959) block terminals? The service cable brought the B- & A-wires to dedicated line terminals, a bare copper wire running from an earthing rod was connected to a third dedicated terminal, there were shellac-coated carbon blocks between both the B- & A-wires and the earth and, finally, fuses in series with the B- & A-wires of the pair before the dedicated instrument connection terminals. How much 'protection' that gave to: (a) the local instrument (b) the exchange equipment (c) an engineer 'up a pole' or 'down a hole' is anybody's guess. ::)Yes, the line of a friend of mine nearby is still connected via one of them! :lol:
The 'protector' in the NTE5 is not a lightning protector, it is only a 2-terminal device and as such there is no path to earth.
Maybe at the higher frequencies of VSDL it is starting to react as a circuit component.
I can confirm that on new NTE5/A's...the most recent ones, there is no surge arrestor, apparently omitted by Pressac on BT's request because they say it has an effect on the VDSL signal. Now it's just the cap and resistor on BT's side.
Perhaps the self-install 'kits' of the future will contain instructions how to identify and remove a SP26 from the NTE5/A . . . :-X
I'll give it a go (on a private circuit) to see how it fairs!
Here's what the newest PCB looks like:
[..]
Therefore, my guess, and it's only a guess, is that T4 would be connected to Earth for old 'Earth Calling' systems
And it was even specified for domestic circuits before all the public exchange equipment was standardised onto the current 'timed break' recall. One old telephone, of 1980s vintage, that I have given to my brother in law for use as his bedside phone has a recessed switch underneath to select the recall method which will be used.I believe that we may be merging memories here ... B*Cat's recollection references (timed and earth) recall which AFAIrecollect was a P(A)BX facility. The switch he refers to allowed the same apparatus (great old word) to be used either on a subscriber (another great old word) line, or on a P(A)BX as an extension, in which case the earth recall allowed the P(A)BX operator to be alerted e.g. to come back and transfer the call elsewhere. With further (A)utomation the operator was replaced with a further dial tone and/or the ability to dial another extension directly. Later, as he said, this was replaced by timed break recall instead.
With the higher frequencies of VDSL2, when compared to that of ADSL2+ (or POTS), the intrinsic capacitance and inductance of such surge arrestors must become significant.
Very much so, would be my guess, for the gas-discharge glow devices. :(
...standing on the shoulders of giants here... :graduate:Well, as B*Cat suggested, BlackSheep has given you the definitive answer, but going back to my original post, the SFI who came out to me changed mine as a matter of course. Whether or not the BTOR/contractor engineer tasked with the installation would do so might depend on whether you asked (as I am sure you would), and whether (s)he had one in the van and could be bothered going back down to get it for you. Lots of tea and biscuits has been known to work! ;) :)
can I ask? - is it in an engineers remit to replace the NTE5 (if it was older) when he comes to install and setup an FTTC connection (for this reason)..?
Here's what the newest PCB looks like:
[..]
That's interesting. Thanks for posting the images, Neil. :)
Has Openreach disclosed the nature of problems that the Surge Arrestor can cause to a VDSL2 service?
cheers, a
So, whatever the differences are in terms of VDSL2 performance, information-wise they don't seem to have 'filtered' through to engineers yet.
As the frequency increases, I speculate that the 'shunt effect' becomes more significant and thus the signal is further attenuated.
ASCII Art
------------------------------------------------------------------------------
^ B-wire ^ |
|
O <--- Surge arrestor, acting as a frequency dependent shunt, applies a load across the pair.
|
|
-------------------------------------------------------------------------------
^ A-wire ^
The spark gap will be seen (by VDSL2 frequencies - certainly 30a) from the FTTC cab as a discontinuity in the transmission line so you will end up with reflections back down the line. Depending on the length of the line this may or may not be an issue.Which may be the cause of (some of) the phantom 'bridged taps' that have been reported on some people's lines (even BS)
in theory the shunt effect shouldn't be that much of an issue, but theory assumes a perfectly balanced pair.However Longditunal AC inbalance (<50dB) occurs as a fault every so often, although this is tested at installation and should be investigated and corrected if it is seen. AIUI >60dB is what they should be looking for and <50dB red flags it.
The spark gap will be seen (by VDSL2 frequencies - certainly 30a) from the FTTC cab as a discontinuity in the transmission line so you will end up with reflections back down the line. Depending on the length of the line this may or may not be an issue.Which may be the cause of (some of) the phantom 'bridged taps' that have been reported on some people's lines (even BS)Quotein theory the shunt effect shouldn't be that much of an issue, but theory assumes a perfectly balanced pair.However Longditunal AC inbalance (<50dB) occurs as a fault every so often, although this is tested at installation and should be investigated and corrected if it is seen. AIUI >60dB is what they should be looking for and <50dB red flags it.
Oh BTW snadge, Sky DLM seems to have finally set a speed for me in the MyBroadband section - 21Mbps down and 1.3Mbps up. Did yours ever update?
...to further add.... ive learned that it was the BT i-Plate that has both RF3 filter and 22mH choke :)Seems even SFI's get confused then eh, BS? :lol:
I have to say, I thought all along you were referring to the i-Plate ??
...to further add.... ive learned that it was the BT i-Plate that has both RF3 filter and 22mH choke :)
I have to say, I thought all along you were referring to the i-Plate ??
But it was interesting to watch everyone smash their own NTE5's up to see what was inside. :lol:Not at all. These were essential scientific experiments that have advanced our collective knowledge. :graduate:
Hmmmmm so snadge perhaps i dont have the surge doobry wotsit in mine
@ 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
i snipped out the surge arrestor today aint noticed any difference
. . .
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
Couldn't have put it better myself B*K! Meow! ;) :)
http://forum.kitz.co.uk/index.php/topic,12520.15.html (http://forum.kitz.co.uk/index.php/topic,12520.15.html) @ post 27!
@ Ixel - how new is the connection? is it VDSL or ADSL?
oh I thought you meant "new" as in only been live a few days...had it been ADSL on that it might have been DLM
anyway, was the change instant? or did it take a few days? cos it appears VDSL uses 'Banded Profiles' which dont seem to reflect better line conditions immediately (and sometimes not at all)....
Just moved into a new place with the wife and 4 kids (holy stress, Batman!). It's just a stones throw away from the exchange, 13dB downstream attenuation! Anyway, ordered a new OR printed NTE5/A to replace the existing LJU2 master and what came in the post was the one without the surge arrestor. Now to get our ISP to take us off the 15dB S/N profile (TalkTalk and YouView...) To enjoy the speeeeed! :-)
Upstream line rate (kbit/s) 989
Downstream line rate (kbit/s) 17342
Line standard ADSL2+
Channel type
Interleaved
Upstream SNR (dB) 9.7
Downstream SNR (dB) 9.1
Upstream line attenuation (dB) 6.9
Downstream line attenuation (dB) 13
Upstream output power (dBmV) 10.5
Downstream output power (dBmV) 0
Upstream CRC 0
Downstream CRC 0
Upstream FEC 108
Downstream FEC 0Upstream line rate (kbit/s) 1020
Downstream line rate (kbit/s) 19367
Line standard ADSL2+
Channel type
Interleaved
Upstream SNR (dB) 9.4
Downstream SNR (dB) 6
Upstream line attenuation (dB) 6.9
Downstream line attenuation (dB) 13
Upstream output power (dBmV) 11.5
Downstream output power (dBmV) 0
Upstream CRC 0
Downstream CRC 0
Upstream FEC 3464
Downstream FEC 0ADSL up time 1 Days 12:34:31
Upstream line rate (kbit/s) 1020
Downstream line rate (kbit/s) 19420
Line standard ADSL2+
Channel type
Interleaved
Upstream SNR (dB) 8.6
Downstream SNR (dB) 6
Upstream line attenuation (dB) 6.9
Downstream line attenuation (dB) 13
Upstream output power (dBmV) 10.5
Downstream output power (dBmV) 0
Upstream CRC 3
Downstream CRC 0
Upstream FEC 28251
Downstream FEC 0