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Post by paterson00 on Jun 30, 2009 6:04:04 GMT
I have seen it a few times now and know a tiny bit about it but would like to know more as i think I may come across it alot soon so any tips or information would be great..
What are its strengths and weaknesses etc and is it ok to have as an interlocking or are others far preferred...
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mrfs42
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Post by mrfs42 on Jun 30, 2009 6:53:25 GMT
I have seen it a few times now and know a tiny bit about it but would like to know more as i think I may come across it alot soon so any tips or information would be great.. What are its strengths and weaknesses etc and is it ok to have as an interlocking or are others far preferred... For a good general overview clicky, pictures clicky, British overview leaflet . The first two links are Australian, and will give probably the most decent amount of detailed information that is openly available on the web - ARTC are a very useful resource. Can't comment really on the viability of the design, apart from it being modular and therefore relatively straightforwardly adaptable/extendable. |
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Post by paterson00 on Jun 30, 2009 19:32:18 GMT
I once went on a TDM course a long time ago and have forgotten most of it but WESTRACE is jogging my memory of the course, Is it a TDM Interlocking or am I getting my wires crossed?
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mrfs42
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Post by mrfs42 on Jun 30, 2009 21:02:00 GMT
WESTPAC is TDM from memory - *scratches head* about FDM.... Hmm. Watch this space.  (for those of you following this): FDM/TDM = Frequency Division Multiplexing/Time Division Multiplexing. If (as is most likely) the data links are driven by WESTRONIC S2 and S3 modules, then it is TDM; unless of course it is fibre-optic. |
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Post by railtechnician on Jul 1, 2009 10:57:33 GMT
WESTPAC is TDM from memory - *scratches head* about FDM.... Hmm. Watch this space. (for those of you following this): FDM/TDM = Frequency Division Multiplexing/Time Division Multiplexing. If (as is most likely) the data links are driven by WESTRONIC S2 and S3 modules, then it is TDM; unless of course it is fibre-optic. Fibre-optic transmission is TDM, usually in a form known as PCM (Pulse Code Modulation) which has become the basic building block of digital transmission systems. From a communications standpoint first there was SDM (Space Division Multiplex or step-by-step) then FDM (Carrier systems) and now TDM (Digital systems). The world now runs mostly on TDM but LT/LU has been doing it for 40 years in places, slow speed scanning is TDM. |
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mrfs42
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Post by mrfs42 on Jul 1, 2009 11:33:19 GMT
Well, y'see the reason I mentioned fibre-optic is because I'm not sure if the clever boffins at Westinghouse use WDM (wavelength division multiplexing) through the fibres, and WDM is a form of FDM.
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Post by Deleted on Jul 1, 2009 17:39:53 GMT
WESTPAC is TDM from memory - *scratches head* about FDM.... Hmm. Watch this space. (for those of you following this): FDM/TDM = Frequency Division Multiplexing/Time Division Multiplexing. If (as is most likely) the data links are driven by WESTRONIC S2 and S3 modules, then it is TDM; unless of course it is fibre-optic. WESTPAC is actually a relay based geographical interlocking system, developed during the early 1960's and the early Mk1 version was used at Euston and Birmingham New Street. Progression through the various versions led to the Mk4A which went into West Hampstead during the early 1980's. WESTPAC was overtaken by SSI and the use of cheaper freewired interlockings. The earlier use of WESTRONIC S2 was generally used in the transmisson of contols and indications to outying WESTPAC relay rooms but now finds a use when connecting an NX panel to an SSI interlocking as the telegrams generated by S2 are compatable with the SSI interlocking. Though the local signalbox interlocking was direct wired to the panel and S2 to outlying relay rooms, there was one fine exception at Euston where the outlying relay room at Camden was linked by two 200 pair microcore cables a little more LT style. Incidently PCM was more for those telecom types, the brainier signalling types kept to FDM and TDM. |
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Tom
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Post by Tom on Jul 1, 2009 18:49:12 GMT
Westrace uses a cycling system which could be compared to a TDM.
The logic inside is ladder logic similar to a PLC, laid out in a similar way to the equivalent relay circuits.
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Post by Tom on Jul 1, 2009 18:51:42 GMT
If (as is most likely) the data links are driven by WESTRONIC S2 and S3 modules, then it is TDM; unless of course it is fibre-optic. As I remember it S2 is used on the Central Line as the Signalling Equipment's Interface to the Site Computer. The links between Westraces on adjacent sites is generally via modem links and telephone cable (Woodford to Roding Valley is, I believe, the only exception). |
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Post by d7666 on Jul 1, 2009 21:29:00 GMT
My telecoms background tells me SDM is ... well not a backronym .... but whatever the term is for a retrospectively applied abbreviation ... and is no form of multiplexing at all.
I've always understood SDM actually refers to one dedicated wire/pair for every channel i.e. such as a 50 pair copper cable where one copper circuit has one connection at a time. It might be switched at the ends i.e. as by a telephone exchange, but the physical link is either not connected [idle] or connected [one point to point connection].
Spece literally means that ... 50 seperately spaced signals ... spaced in the cable.
Its quite possible LT/LU had its own standard or terminology ... I sure know LU can be unique ... but certainly from outside I have never heard SDM used to mean a form of multiplexing, only to compare fixed copper pairs with TDM and FDM
I am certain I recall this correctly, because I recall the instructor on about you can put a TDM signal down a switched copper pair .
--
Nick
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Post by d7666 on Jul 1, 2009 21:35:06 GMT
My telecoms background tells me SDM is ... well not a backronym .... but whatever the term is for a retrospectively applied abbreviation ... and is no form of multiplexing at all. I've always understood SDM actually refers to one dedicated wire/pair for every channel i.e. such as a 50 pair copper cable where one copper circuit has one connection at a time. It might be switched at the ends i.e. as by a telephone exchange, but the physical link is either not connected [idle] or connected [one point to point connection]. Space literally means that ... 50 seperately spaced signals ... spaced in the cable. Its quite possible LT/LU had its own standard or terminology ... I sure know LU can be unique ... but certainly from outside I have never heard SDM used to mean a form of multiplexing, only to compare fixed copper pairs with TDM and FDM I am certain I recall this correctly, because I recall the instructor on about you can put a TDM signal down a switched copper pair so it occupies its own ''space'' without a protocol / signalling change, and it is not multiplexed, but to put anything down a TDM link you do have to change protocol / signalling to make it TDM - and that means it ain't ''SDM'' any more becasue it is now multiplexed. -- Nick |
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Post by railtechnician on Jul 1, 2009 23:52:00 GMT
WESTPAC is TDM from memory - *scratches head* about FDM.... Hmm. Watch this space. (for those of you following this): FDM/TDM = Frequency Division Multiplexing/Time Division Multiplexing. If (as is most likely) the data links are driven by WESTRONIC S2 and S3 modules, then it is TDM; unless of course it is fibre-optic. WESTPAC is actually a relay based geographical interlocking system, developed during the early 1960's and the early Mk1 version was used at Euston and Birmingham New Street. Progression through the various versions led to the Mk4A which went into West Hampstead during the early 1980's. WESTPAC was overtaken by SSI and the use of cheaper freewired interlockings. The earlier use of WESTRONIC S2 was generally used in the transmisson of contols and indications to outying WESTPAC relay rooms but now finds a use when connecting an NX panel to an SSI interlocking as the telegrams generated by S2 are compatable with the SSI interlocking. Though the local signalbox interlocking was direct wired to the panel and S2 to outlying relay rooms, there was one fine exception at Euston where the outlying relay room at Camden was linked by two 200 pair microcore cables a little more LT style. Incidently PCM was more for those telecom types, the brainier signalling types kept to FDM and TDM. LT has been using high speed scanning (dripping blood) for many years and that has been referred to as bastardised PCM for as long as I can remember, it is of course less complex than voice PCM systems even though it has 108 channels because it is not sampling a constantly varying signal on every channel and can operate with a lower sampling rate. FDM of course is a telecoms system developed long ago and was the backbone of trunk telephone switching over coaxial trunk cables before the advent of digital transmission systems and fibre optics. In the end the majority of signalling will be telecoms based, that is inevitable and having spent almost my entire career with one foot in the telecoms camp and the other in the signalling camp I would never regard those in signals as the brainier types! It really is very much a level playing field these days as all the electrical, electronic and related disciplines converge. |
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Post by railtechnician on Jul 2, 2009 0:08:19 GMT
My telecoms background tells me SDM is ... well not a backronym .... but whatever the term is for a retrospectively applied abbreviation ... and is no form of multiplexing at all. I've always understood SDM actually refers to one dedicated wire/pair for every channel i.e. such as a 50 pair copper cable where one copper circuit has one connection at a time. It might be switched at the ends i.e. as by a telephone exchange, but the physical link is either not connected [idle] or connected [one point to point connection]. Spece literally means that ... 50 seperately spaced signals ... spaced in the cable. Its quite possible LT/LU had its own standard or terminology ... I sure know LU can be unique ... but certainly from outside I have never heard SDM used to mean a form of multiplexing, only to compare fixed copper pairs with TDM and FDM I am certain I recall this correctly, because I recall the instructor on about you can put a TDM signal down a switched copper pair . -- Nick SDM did not come from LT/LU but from the GPO ! It is not a retrospective term at all, I did my apprenticeship as a telephone engineer from 1970 and it was older than that. It was the term given to step by step electromechanical switching and is indeed a form of multiplexing although each function is on a completely separate path simultaneously! This not only applied to calls originating at the same time but to the actual signals between switches through the exchange. Most people won't know that although a telephone requires only one pair of wires to the exchange within the exchange it required as many as five wires per circuit within the exchange. These days that is all done digitally with 32 channel PCM links and as you correctly suggest an external 32 channel PCM system requires just two pairs of wires for Tx and Rx although there is usually a third test pair per system as well. I guess your Telecom background is somewhat shorter than mine. |
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Post by d7666 on Jul 3, 2009 10:25:23 GMT
Interesting ...  I went straight in on digital PABX in early 1980s ... and not with GPO/BT either ... and I never looked at electromechanical gubbins ... however the course instructors [all 3 of them] were ex-BT main exchange engineers [one from Mondial IIRC] and based a lot of their course material on ex-BT stuff. I'm a bit surprised then that SDM could have been given that wrongly ... I did dig out the notes from 25+ years ago and it definitely quotes SDM as a wholly seperate path through space with no switching, so its not my memory thats addled  this time around. -- Nick |
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Post by d7666 on Jul 3, 2009 18:22:30 GMT
If (as is most likely) the data links are driven by WESTRONIC S2 and S3 modules, then it is TDM; unless of course it is fibre-optic. As I remember it S2 is used on the Central Line as the Signalling Equipment's Interface to the Site Computer. The links between Westraces on adjacent sites is generally via modem links and telephone cable (Woodford to Roding Valley is, I believe, the only exception). All SER on Central Line have S2 links somewhere in the comms chain between the interlocking and the LSC. The Westrace sites with WIP interface are *primarily* at the eastern [1] end of the line, the relay sites with SEI interface *primarily* at the western [1] end. Strangely, the Woodford / Roding Valley fibre link was mentioned in a work meeting only this week. [1] Cue someone to write a list of which site has what interlocking type and pedantically point out every exception. -- Nick |
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Post by paterson00 on Jul 3, 2009 18:33:39 GMT
[1] Cue someone to write a list of which site has what interlocking type and pedantically point out every exception.
Not a bad thing for those trying to learn
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Post by d7666 on Jul 3, 2009 19:20:18 GMT
I do have this data but not here at home , its at work, and if I post a list now I'll only need to get one wrong and confusion reigns with a series of posts and counter posts.
The Westrace sites on the JLE I can do off the top of my head, they are at every station STR to GRP inclusive, plus SMD. All the other Jubilee interlockings are V-frames, including CHC.
AFAIK there are no Westracii on LU outside of the Central and Jubilee, nor indeed, any others in the UK that I am aware of.
--
Nick
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mrfs42
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Post by mrfs42 on Jul 3, 2009 23:38:49 GMT
AFAIK there are no Westracii on LU outside of the Central and Jubilee, nor indeed, any others in the UK that I am aware of. -- Nick The bicycling signalman at Nairn had his tyres deflated by a Westrace. |
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Post by d7666 on Jul 4, 2009 8:58:21 GMT
Phewww to ''AFAIK'' and to ''that I am aware of'' That is exactly why I was not going to attempt a list of Central line Westracii without a reference - there are 49 stations and 2 depots. The chances of me getting all 51 sites right without looking is low ;D I can remember other things about the 49 stations and get it right without looking ... but those are with eqpt. directly related to my job ... interlockings are not in my domain. Seriously I did not know that about Nairn ... and nor did a man from the Chippenham area who one might have thought ought to have known. A quick google: www.signalbox.org/sectionc.php?year=2000-- Nick |
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Post by Tom on Jul 4, 2009 22:20:50 GMT
This simple list is:
West Ruislip - Westrace
Ruislip Gardens & Ealing Broadway to North Acton - Relay
East Acton - No SER (all circuits in North Acton SER)
White City - Westrace
White City Sidings - Westrace
Shepherd's Bush to St Paul's - Relay
Bank - No SER (all circuits in St Paul's SER)
Liverpool Street to Epping including Hainault Loop - Westrace
Note that I have made no attempt to differentiate between Auto and Controlled areas.
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Post by londonse on Jul 6, 2009 9:34:01 GMT
This simple list is: West Ruislip - Westrace Ruislip Gardens & Ealing Broadway to North Acton - Relay East Acton - No SER (all circuits in North Acton SER) White City - Westrace White City Sidings - Westrace Shepherd's Bush to St Paul's - Relay Bank - No SER (all circuits in St Paul's SER) Liverpool Street to Epping including Hainault Loop - Westrace Note that I have made no attempt to differentiate between Auto and Controlled areas. Not being a signalling expert although reading through some of the threads on here has given me a taste why is there a difference on the Central between Westrace & Relay. Paul |
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Post by Tom on Jul 7, 2009 23:02:29 GMT
The central line was originally supposed to have been all-relay.
However, there were a number of teething problems with the larger relay sites (West Ruislip for one) and it was decided that Westrace was a better option as there were less relays required (thereofre fewer failure points) and less space is needed.
The rooms are still big enough for the relay interlockings.
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Post by d7666 on Jul 9, 2009 19:56:25 GMT
This simple list is: West Ruislip - Westrace Ruislip Gardens & Ealing Broadway to North Acton - Relay East Acton - No SER (all circuits in North Acton SER) White City - Westrace White City Sidings - Westrace Shepherd's Bush to St Paul's - Relay Bank - No SER (all circuits in St Paul's SER) Liverpool Street to Epping including Hainault Loop - Westrace Note that I have made no attempt to differentiate between Auto and Controlled areas. Yep correct AFAIK - including the comments about EAA and BAN eqpt at NOA and STP SERs. w Westrace r relay WER w RUG r SOR r NOR r GRE r PER r HAL r EAB r WEA r NOA r EAA r WHC w WSC w SHB r HOP r NHG r QUE r LAG r MAA r BOS r OXC r TCR r HOL r CHL r STP r BAN r LIS w BEG w MIE w STR w LEY w LES w SNA w SOW w WOO w BUH w LOU w DEB w THB w EPP w WAN w REB w GAH w NEP w BAR w FAI w HAI w GRH w CHI w ROV w good job I had not tried this off top of my head as indeed I had forgotten about WSC, hence there are 50 sites not 49. -- Nick |
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Post by d7666 on Jul 9, 2009 20:54:35 GMT
Concerning the change from relay to Westrace interlocking, I quote from the IRSE paper CENTRAL LINE RESIGNALLING by Humphrey, Brown, Crisp and Dodsworth, presented 04/11/1994 at IRSE technical meeting.
'' ... Technology. In 1989 the contract for modernisation of the signalling was let with a specification based on proven equipment. The specification called for relay interlocking, jointless track circuits, fixed block ATP ...... In a relatively short time scale the project team fond itself reviewing the original requirements. Changes were made to take advantage of new techniques and new technologies. Changes included ...... a change from the relay interlockings to a solid state interlocking known as Westrace.
Westrace is a modular interlocking system originally developed for use on small interlockings. Now from further development the system is suitable for larger ATP interlockings on the Central Line. The current situation is that 22 relay interlockings have been installed ....... by the end of the project 24 Westrace interlockings will be in use ...''
I understand that West Ruislip was originally relays but later changed out to Westrace, but that White City has always been Westrace.
--
Nick
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I went straight in on digital PABX in early 1980s ... and not with GPO/BT either ... and I never looked at electromechanical gubbins ... however the course instructors [all 3 of them] were ex-BT main exchange engineers [one from Mondial IIRC] and based a lot of their course material on ex-BT stuff. 
this time around.
