Editorial Fourth generation rnodenas

This issue, the largest ever, covers a wide by Dennis Anastaslades BTE Business UK network where it achieves optimum · range of topics. In particular may I call your Systems Division PGT6 performance by matching to the network attention to the articles by George Clark and 'Fourth Generation' is literally the fourth characteristics. Trevor Morton-Holmes on 'Static', a generation of modems to be supplied by Other special features in a feature-rich . phenomenon of which we are all aware but British Telecom, but there is more to it than range are that PSTN modems offer auto­ which has assumed vastly increased that. Fourth Generation is also a family of answer, auto-disconnect and adaptive importance in our modern micro-electronic modems with commonality of design and equalisation as standard, whilst private circuit age. If your job involves handling static construction covering the whole speed range modems boast such options as down-line sensitive devices make sure that you know from 300 to 9600 bit/s. It includes all the V loading, remote unattended diagnostics and and apply the proper precautions. series recommendations, plus some extras, auto switching to standby lines. Fourth Today the emphasis is on Quality and the and is the most comprehensive range of Generation modems were designed to have a need to 'get it right first time'. Quality British made modems available anywhere. beneficial impact on maintenance activities. Manuals and checklists are now widely All modems in the range use the most up­ For example, occasions when a available. Their aim is to enable us to provide to-date technology, incorporating LSI devices maintenance engineer goes out to find a our services economically and efficiently as and micro-processor control. They are faulty terminal should be significantly our standing with our customers is designed on a modular basis with common reduced. And that's because user friendly determined by how we serve their needs and ancillary equipment so that a mixture of types tests which include local and remote digital not by reports of our business successes as of modem can be housed together on the loop, analogue loop and self test enable the reported in the financial press. same shelf. When a user has a new communications manager to locate exactly requirement, for example upgrading the where his system is at fault, often without Ken Jones speed of operation, a new card is simply assistance from the remote end. And when a Editor inserted in the case or shelf in place of the visit is necessary, that soldering iron can be old. Every member of the family has left behind. Simple plug and socket comprehensive diagnostic capabilities and connections for line, power and terminal nearly all are suitable for operation on both equipment ease the task of dismantling a unit private circuits and the PSTN. to replace a faulty module. Space forbids a catalogue of model types Racked installations are supplied complete and numbers but one or two are worthy of with a telephone module, so that any line in mention. Datel modem 4124 is unique in the the cabinet can be patched through and marketplace combining as it does the V21 tested. and V22 standards. A valuable feature is its Standardisation of design means greater auto-switch capability from 1200 to 300 bit/s. use of common components thus reducing A recent addition to the range is the Datel the variety of spare parts to be stocked and modem 4961 which is a non-CCITI 9600 bit/s carried about. modem designed specifically for use on the Second level maintenance is provided by- MerlinCare, a service operated by British demonstrate that we have a product line clear that modems will be with us for the Telecom Factories on behalf of Merlin. which is second to none. foreseeable future- they are currently living MerlinCare provides a repair and return They also express strong customer in harmony with digital networks by providing service on faulty equipment out of warranty, a confidence in our technical expertise and end links for access to Packet Switching and clearing house service for items in warranty product support activities. Merlin Fourth X-Stream services- and the high-speed and- rapid replacement for any item. Generation modems are capturing an duplex modem is likely to be a cost effective The impact on the marketplace of Fourth increasing share of the market by their data transmission system for some time. The Generation modems has been significant. customer appeal, and the old criticisms of recent publication of the CCITI Major data users have already placed large expensive, bulky, power-hungry products recommendation for 9600 bit/s 2-wire orders for the products- £3M from Midland have at last been silenced. modems will see this situation being Bank, £200K from Tarmac Roadstone Limited What of the future for modems? In this maintained as products are developed in this and £1.5M from Royal Bank of Scotland are digital age will we see the demise of these field. Fourth Generation is a success for just a few examples. These orders for devices? It seems improbable in the shorter British Telecom data communications and a nationwide data communications networks, term, although there will come a day when success for British design. won in the face of fierce competition, amply they are no longer required. Meanwhile it is (01-631 2100)

2 The Edgele~ eleetronie queueing equipnaent by Ken Lowe Liverpool District (EM51) being returned to any caller after this figure commissioning itself is carried out with the BACKGROUND- The rising cost of has been reached, thus with 3 operator help of a program written in basic. Hard copy maintaining the ageing electromechanical positions staffed 4 calls are allowed into the of bar charts, operators per shift and call Directory Enquiries queuing system at queue the 5th call receives EET. This method failures can be obtained using the PET VDU Edgeley in Manchester South Telephone Area of queue management has met with and printer. highlighted the need for a cost effective customer approval as it eliminates an The system is entirely self contained with replacement which would fulfil requirements extremely long wait which previously was a incoming and outgoing circuits, call switching from operators, management and common cause for complaint. Further to this and monitoring equipment, microprocessor maintenance engineers. The design and build aspect, the supervisor's desk top console has with interface and power pack all brief was given to a small but enthusiastic a display which indicates the length of the accommodated within a cabinet which is no team of engineers led by Jim Hirst and Dave queue and, depending on the position of a larger than two four drawer filing cabinets Donnelly, who completed the prototype, control key, either the number of positions stood side by side. The equipment is virtually including software within 10 months. The staffed or the number of engaged tones silent and with the PET, VDU and printer atop team effort was suitably acknowledged by an returned to callers. And an Audio Visual the cabinet, it can be sited within the award from the National Awards Committee. Alarm is activated should the number of switch room. Production of the system was undertaken by engaged tones exceed a preset value thereby Operating procedure is similar to existing BM FACD for national provision and work is alerting the supervisor to the possible need systems with night service concentration now under way to develop the system for use for an adjustment in staffing levels. The giving two appearances on the manual board. with the 151 Repair Service Control. training supervisor, from a 'listen only' Any call can be force released from the console can monitor calls without any operator's console back to the incoming OUTLINE- The system assembles calls from noticeable degrading of transmission. relay set by using the FR key. During night 48 incoming circuits into a queue on a first The system provides a repeat attempt to a service if force release is needed, the key on come first served basis under the control of a different operator should the first routing the operator's console has to be used as this single 8085 microprocessor. Passing through attempt fail. Failures like this and the status facility is not cabled to the night service a single full availability matrix, made up of of all parts of the system are stored to appearances. TXE4 Incoming Junction A Switches, the calls provide statistical and faulting information for Under total failure conditions, direct . are offered to a maximum of 32 operator operator management and engineering connection of incoming circuits to operators positions including 4 monitorial positions and maintenance use. Information retrieval is on a one-to-one basis is made using a 4 outgoing transfer circuits. carried out using a Commodore Personal manually operated key. Control of the queue is provided Computer (PET) with VDU and printer. automatically by the microprocessor on the Programs written in basic and stored on pre­ OPERATION- Referring to fig 2; at any time, basis of 1 · 3 calls to every staffed position in recorded cassettes are issued to the relevant the processor will calculate from the number strict rotation with equipment engaged tone staff as the unit is commissioned. Indeed of operators in service how many calls it will• 3 allow to join the queue and set either the ring number of i/c relay sets will have toggles set relay now operated calls the processor which tone or busy tone toggle in the i/c relay set as for ring tone so that a calling loop applied to allocates a queue number to this call. The appropriate. If the queue is closed, the the i/c relay set will result in ring tone being processor takes the lowest queue number toggles in all the free relay sets will be set to returned to the caller. In the former case, the and routes it to an operator as and when one busy tone so that a calling loop will result in processor takes no further part in the becomes free. Having decided which cross busy tone being returned to the caller. If proceedings but in the latter, as ring tone is point to operate, the processor then marks however the queue is open the appropriate returned to the caller, a contact of the line the X and Y coordinates of the reed relay

Figure 1: Block diagram of EEQE

~ ~illR\ <,...---->~-, Printer Supervisor's 8085 control display X marking Power

======~~Incoming ::J ~ Reed matrix from junctions ·c::; 48 x 36 cross-points emergency To or selection services exchange levels. prompt 45 circuit Incoming from A board 46

48 32 Training Monitorial Ordinary supervisor's operators operators listen-only monitor

0 ~~·-0·-:,·-·~{]{] {]{] 0 " \!====\0° o=o ~-----':> ~ @ @ @I

4 Line circuit Cross-point (reed matrix) +

I _I

Incoming junction p

I

•ll __ ~....._H__ I __ ----4 H r L2 I

L Ml M 2

Tone Tones inhibit

Ring tone and busy tone supplies and memory

Set Set for for Break on Call ring busy insertion tone tone

Mark X -----r------,

To microprocessor

Figure 2: Circuit Diagram of E EQE 5 Materials matrix by applying - 26V to the i/c relay set operator. The monitorial console is fitted with advieefor M lead (Mark Y) and a - 50V to the operators a push button keypad to enable outgoing H lead (Mark X), this results in one CP relay calls. On completion of transfer, the original P.W.B's being operated as only one diode D1 is operator is free to accept another call after a forward biased. Contact CP1 operating built in delay of at least two seconds. by John MoHram MC1.6 Birmingham provides a hold path from L2 contact earth The PET computer software written in Printed Wiring Board (pwb) assemblies were via CP relay coil to -26V, as diode D1 is now basic comprises management and statistical once considered a throw-away item. Today, reverse biased the original mark X and mark information retrieval whilst engineering the assembly may comprise expensive semi­ Y conditions are no longer needed. The maintenance needs are catered for by 5 conductor components on a multilayer pwb contacts CP2, CP3, and CP4 extend a programs. with delicate gold plated edge contacts or metallic path to the operators circuit and a • To identify the sources of alarms and to two-part connectors. continuity detector checks the path. If this reset same. Procedures for the repair and modification check fails, another attempt is signalled by • To give the states of lines and operator of pwb assemblies need to be tightly the processor. If however the check is valid, positions. controlled in deference to the replacement then the call LED is lighted on the operator • Call trace within the switchblock either cost of the item. Last year saw the issue of console. forward or backward. BS6221; Part 21 'Guide for the repair of The call is answered by the operation of • Enables the user to temporarily change the PWBs'. BT Materials and Components Centre the answer key. Contacts on the answer key line and operator state of call as well as (MCC) were represented on the committee connect the speech path as well as earthing manually steering a call from any line to which compiled this document and have now the P wire which suppresses the ring tone any operator. produced a list of suitable materials which supply. The transmission bridge is the familiar • Gives access to the System Technical may be used for this purpose. stone type with half in the line circuit relay set Officer Fault Log. The MCC memorandum MC5/222/01/84(0) and the other half in the respective operator's • Setting of system calendar clock. 'List of acceptable materials for the repair console. In order to preserve the trans­ The system has proved itself satisfactory and modification of pwb's' details information mission level when the supervisor inserts a to customers and BT staff and with several on suitable adhesives, fluxes, solvents and handset plug, the receivers are connected in million calls handled successfully has wire insulants. Whilst the listings are not parallel but the transmitters are in series via justified the faith of the design and build exclusive, the materials given are of known a break contact in the supervisor's jack. team. quality and will introduce no hazards to the In the event of an ordinary operator being (051-229 5585) assembly if correctly used. unable to deal with the call due to a need for Copies of the MCC Memorandum may be further enquiries such as to a distant DO then obtained from L.A. Pillinger, MC5.2.2.2. the call is transferred to a monitorial position Telephone No. 021 772 2361 Extn. 2058. using a sub routine which releases the (021-7081111 X 260) original cross point and operates another one which connects the call to a monitorial 6 BTl 4MRz R~pergroup Switehing equipnaent by P D Taylor BTI/IL3.3.3.1 the International Network Maintenance • communicates with the INMC/NC SBC Equipment is currently being il'lstalled to CentrB/Network Co-ordination Centre • monitors the status of the switch matrices enable the semi-automatic changeover of (INMC/NC), in Caroone House, London. and changes the state of the switches. failed international hypergroups (HGs) to The frontier stations will be linked to the • operates the ASE Switch Unit No 1OOOA International Protection Network (lPN) SBC via a private wire network and when a receive HG is switched to an lPN HGs at frontier stations. This facility will communication will be an X25 protocol, 1200 route. permit a fast restoration of service with baud data stream, providing high security and • raises alarms when receive hypergroup minimal traffic loss. It will be particularly low susceptibility to interference. Figure 1 pilot~ fail. beneficial on instances of out-of-hours shows the equipment involved. These functions are performed by a shelf failures involving non 24-hour staffed of 62-Type equipment designed within BT and frontier stations where service will be The remote facilities named Equipment Message Transmit restored pending the arrival of 'call out' The SBC has menu driven software which will Receive No 1A (MTR Shelf). The MTR shelf is staff to localise and repair the fault. enable IN MC/NC staff a general purpose, microprocessor based • to record the current status of a frontier equipment configured to suit a particular The remotely controlled wideband switch station's HG to lPN HG connections. application by utilising specifically designed matrices and asociated monitoring and • to effect connections or disconnection at a interface cards and appropriately activating circuitry necessary to provide this frontier station between any HG and any programmed PROM software. capability have become known, collectively, lPN HG in the station, in either direction of Also provided within the station are a as 4MHz HG SWitching Equipment. It is being transmission. display shelf, named Equipment Switch installed in Scarborough, Lowestoft, • to connect at a frontier station, using Monitor No 1A and an Equipment Bypass No Winterton, Aldeburgh, Tolsford Hill, St appropriate attenuation (usually 25dB), a 1A panel. The former gives the local Margarets Bay, Broadstairs, Widemouth Bay, received lPN HG to a transmit lPN HG, maintenance staff a visual indication of the Eastbourne and Land's End repeater stations thereby looping a HG through the station. current status of the transmit and receive and in the Goonhilly and Madley Earth The SBC will also alarm upon the loss of switch matrices in their station. The Stations. the 1552kHz pilot on any receive hypergroup equipment bypass panel enables the local The equipment will operate in conjunction in the frontier stations, alerting the INMC/NC maintenance staff to remove the 4mHz with existing station Access and Switching staff to the hypergroup failure. Switching Equipment from service and revert Equipment (ASE or ES No 1005A). It provides to BSE manual patching. an alternative to the patch panel of the Frontier station equipment Finally, the 4 mHz Switching Equipment existing Broadband Switching Equipment At each station transmit and receive relies upon Hypergroup Monitoring Units (BSE or ES No 1007 A). The system will be hypergroup switch matrices must be 1552kHz to detect pilot failures on receive supervised and controlled via a BT Factories installed, together with control equipment traffic hypergroups and to pass a fail small business computer (SBC) situated in which condition to the MTR Shelf. - 7 Figure 1: 4mHz Hypergroup Switching Equipment These equipments are described briefly in .(Block. . . . . schematic...... only,. . . . actual. . . . . interconnections...... may. . . . not. . . be. . as. . . shown.)...... the following paragraphs . The switch matrices H.G.·=====----;:::=:::;--, These are constructed from strips of coaxial : *(Showing only one Direction reed relays, to a size permitting any of the : of transmission) S.T.E. . station traffic hypergroups to be connected to any of its lPN hypergroups. Additional capacity is provided to facilitate lPN through patching and the matrices also incorporate 75 ohm termination strips to terminate lPN HGs or standby HG paths currently not in • use. A maximum of 19 HGs and 7 lPN HGs can be accommodated. Each matrix assembly is mounted in a • Type 62 shelf frame and one matrix is • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • required for each direction of transmission. The matrices are cabled in parallel with the station BSE, between the station ASE and the Frontier newly fitted Equipment Bypass 1A. See station figure 2.

Message transmit and receive Frontier ...... equipment station The basic general purpose shelf comprises a Frontier station backplane, two power converter units (PCUs), ...... a central processor unit (CPU) and an Alarm . ' ...... ::'.., ...... and Services card. The PCUs are paired for security, provide + 5V, + 12V and -12V supplies and in this application they detect Key:- power failures to the ES1 012A. Traffic path* The CPU is based upon the Intel 8085 UINTIM *(Showing-----= only one direction of transmission) microprocessor. It incorporates up to MTR shelf 40Kbytes of PROM and two HDLC data link =====~= control line controllers either of which may communicate -----= Multipoint with the INMC/CC SBC through the back­ network plane and modem link. The Alarm and Services card can raise station alarms. It incorporates a 4 segment, alpha-numeric 8 Figure 2: General arrangement for lPN at frontier stations using LED display which provides information about 4mHz hypergroup switching equipment any operational faults on the 4mHz TX (normal route) Hypergroup Switching Equipment. A push button edge switch on the card enables MTR shelf testing routines to be called up. TX BSE (ES 1007) Routines can be developed for the interface STE cards as well as the essential shelf cards. Transmit The tests are executed and progressed using four push button switches on the Alarm and TX 1PN Services card. The backplane permits up to 13 interface cards to be connected to the shelf. It interfaces the shelf to other equipment and incorporates two V24 compatible sockets for Through connection to modems. Additionally, it patch attenuator accepts a hardwired 'key' which enables each MTR shelf to be given a unique identity. Figure 3 shows how the MTR shelf and its interface cards connect with the other Multipoint equipment. circuits Equipment to & from bypass 1A central Interface cards control For the 4mHz Hypergroup Switching console Equipment purposes, three types of interface card are employed in the MTR Shelf. • Alarm interface card. This card can accept BSE (ES1007) up to 48 alarm conditions. It is the means by which receive hypergroup pilot failures RX 1PN in the station are brought to the attention of the MTR shelf. A change of state in any alarm status is communicated to the SBC Patch Eqlr Patch Eqlr when it polls the station MTR shelf. • Switch matrix cards. Each card serves up to 4 columns by 8 rows of a switch matrix. RX STE The card basically consists of 32 latching relays which operate 32 of the reed RX (normal route) switches in the switch matrix. • RC 1OOOA Driver card. This card provides enable and activate pulses to the Switching -9 Figure 3: 4mHz Hypergroup switching equipment block diagram Transmit Tx HE paths equipment Tx HE paths switching No 1012A

Equipment message transmit receive 1A(MTR) Switch matrix I • card(s) I , Alarm& A I H/G alarm services K flex block card ~ I Alarm interface Monitor units I .. card No 1552 Multipoi nt MTRCPU I ,. other alarms circuits A I 1-- card to& fro m- K RC 1000A Ecoble } central 1-- ~ : Backplane .. control - driver(s) Activate { su·, 1oooA Power ,. Monitor via B.S.E. converter .. : 1---

~ I Switch matrix I .. card(s) Power I , Equipment A I bypass ~ converter paths ., I No1A PN I I I ~ I paths Power supervisorys from ES 1012As

1-- Receive equipment Equipment --- Rx HE paths Rx HE paths switch switching monitor 1A Switch monitor No 1012A card

Monitor card

10 Units No 1OOOA in the station ASE. These Equipment maintenance switches have to be operated when receive The shelf diagnostic facilities in the MTR shelf 'Serarnllled hypergroups are switched to lPN HGs. The should greatly aid identification of a faulty card also monitors whether the SW1000As unit. Discussions are in-hand to arrange for rnegs' are in the main or standby positions. It faulty MTR cards to be repaired in an serves up to 16 SU1000As. International Repair Centre (I NT ARC) in by Ray Carter N N/SSP1.3.1 London. The routings of many MegaStream circuits Monitor shelf The reed relays in the switch matrices are now likely to include one or more Digital This 62-type shelf is installed adjacent to the have a proven high reliability. Should one fail Line Sections (DLS) provided with MTR shelf. The front panel incorporates an the strip can be removed from the matrix and Regenerators 15B. LED array which represents the cross points replaced by a new one. Again, an I NT ARC is The Regenerator 15B, which replaces the of the switch matrices. A lit LED represents a being considered to undertake the repair of Regenerator 15A, is a terminal regenerator made HG to lPN HG connection. More LEDs faulty strips. fitted in the Line Terminating Equipment (L TE) indicate the failure of pilot tones on the Spare MTR cards and matrix strips may be rack at each end of a DLS. working hypergroups. held at district centres or centrally, in The Regenerator 15B differs from the London. Regenerator 15A in that the power is parallel Bypass equipment The Equipment Bypass 1A is made to fed rather than series fed and it has two Also built to 62-type practice, one shelf standard BT specifications and will be modes of operation namely, suffices for 61PN HGs. By moving 'U' links repaired on site. The HG monitoring units • Scrambler out- in this mode the each lPN may be connected to the ES1012A 1552kHz are being provided as standard regenerator is transparent and operates in or to the BSE. The shelf also incorporates the items of repeater station equipment and the the same way as a 15A. attenuators necessary for the lPN HG maintenance procedure will be similar to that • Scrambler in- in this mode the transmit through patching. used for LMSs No 18A. signal to line is scrambled and the receive The SBC equipment in the INMC/NC signal from line is descrambled. 1552kHz hypergroup monitoring unit (duplicated to provide worker and spare units) Note:- all signals are in correct HDB3 Based on the Level Measuring Set No 18A, will be maintained by BT Factories, under format, only the information content is the unit extends alarm conditions to station contract. scrambled. alarms, and to the MTR shelf, when the (0 1-936 3365) receive hypergroup it is monitoring fails. A fail The Regenerator 15B was designed and is considered to have occurred if the introduced to overcome the high level of 1552kHz pilot level falls below a pre-set crosstalk caused by frame synchronism of threshold. The hypergroup is considered to the 2.048 Mbit/s outputs from System X be restored to normal when the pilot level is exchanges by scrambling the signal raised above a different pre-set threshold transmitted to line. The scrambling facility level, typically, 'fail' on pilot 6dB low, 'restore' has also been used to good effect on on pilot 3dB low. A non latching receive MegaStreams carrying frame synchronous attention key is provided: Operating the key signals from digital PABXs. will silence the station alarm and it will not Experience of late has shown that certain reappear when the hypergroup is restored. tests applied to DLSs in the past do not show -11 Customer serviee systems the way ahead up problems when Regenerators 158 are byE A Magee start at the moment a customer first makes involved. Many of us in BT have long recognized contact with us- either by telephone or in Further work is necessary to fully detail all that there are shortcomings in the service person. First impressions are crucial! appropriate tests but to date the following we provide to our customers. Until quite Currently, there are a multitude of interfaces guidelines have proved successful. recently our customers had little choice between our customers and ourselves and, -End to end tests using a pseudo-random bit but to use our services. Not unnaturally in needless to say, this causes confusion. sequence with error detection in the Binary such a safe environment, the need for Customers find themselves passed from mode will highlight problems. This can be change and the provision of better service person to person, from department to done using testers 232 for error detection to customers did not feature high on our department. What we really need to do is to and testers 169 or 254 for pattern list of priorities. make it easier for the customer by reducing generation. the number of possible contact points. We -Loop tests are not valid as problems can Liberalisation changed all that. Suddenly we need a Front Office. Ideally, this will be a be masked. found ourselves in the real world, with real single point of contact at which we will be -HDB3 tests on DLSs containing live competitors, fighting for our market able to handle the majority of customer Regenerators 158 are not valid when share. enquiries. The tasks that may be handled by performed on the LTE test points. The Management Consultants, McKinseys, Front Office Staff include simple orders, -HDB3 tests are valid on DLSs containing worked together with LCS senior managers to billing enquiries, fault reports and general Regenerators 158 if performed on the draw up a plan which would put LCS in the enquiries. HDB3 monitor point on the front of the best possible position to compete effectively. A successful Front Office operation will regenerator. It must be noted however that Essentially the plan was to change the depend upon our having up-to-date this test will only show errors arising in that business to one in which the satisfaction of information about our customers immediately particular DLS. HDB3 errors in preceding customer needs was the major concern of available. DLS sections will not be seen. every one of us working within LCS. Bringing CSS (Customer Service Systems) will It is hoped that further information can be about such a major change in emphasis replace nearly all of the existing computer given later. Enquiries to Ray Carter demands organisational and cultural change. systems used by LCS. All the information NN/SSP1.3.1. on 01-4321309/1310. It also demands that we have top quality relating to one customer will be held within a (01-432 130911310) systems to help us run the business. The District database. Unlike many of the existing computer systems were never systems with which we are familiar, the designed to support this type of operation - requirements of the end-users (all of us!) they use incompatible hardware and were the foundation upon which the CSS was software. And, even more important, they built. were not designed with the customer in mind. The Customer Service Systems Really top class customer service should Directorate was established in late 1983 to 12 develop CSS and to assist in its The NUG has two distinct parts Figure 2 implementation. Because of limitations of • Consultative Panels comprising District space it is impossible to describe the roles of Managers, Area General Managers, Deputy 1. Manpower Resources General Managers, Heads of Division, 2. Materials and Transport the individual groups shown in Figure 1. I 3. Billing intend therefore to concentrate on the role of Heads of Group, Regional Controllers and 4. Network Management the National User Group (N UG) and its Heads of Section who come together on a 5. Order entry and processing relationship with the System Design Group part-time basis to verify, confirm and 6. RSC entry and processing (SDG). endorse the individual application system 7. Market intelligence 8. Revenue Forecasting and analysis Unlike any other major projects the requirements. 9. Financial and Management accounting Business has undertaken it was decided from • The Information System Manager (ISM) 10. Operator and Directory services a very early stage that the 'end user' would teams made up of seconded Area, Regional be directly responsible for defining the and Headquarters staff. The teams include facilities and information systems that would COs, STs, TOs, Band A (Inspector}, Band B The Network Management Team is one of satisfy District operational requirements. The (TS}, Band C (AEEs) and through to level 2 the larger ones with a responsibility for 7 National User Group was formed to ensure and 3 (EES and HD's). Between them the applications: Internal Data, Internal Planning 'end user' involvement in the design of the ten teams will look at 35 individual and Projects, Internal Maintenance, External systems. Its structure reflects the uniqueness applications. Figure 2 shows the Data, External Planning and Projects, of its role and position within the responsibilities of the individual ISM teams. External Maintenance and Resource organisation. Estimation. Both internal and external maintenance applications can be further broken down into Figure 1: CSS Directorate .-----., corrective, preventative and routine Programme I LCS Computer I maintenance. External preventative director : steering group : maintenance revolves around the 'Biackspot L-----....1 Analysis point'. Figure 3 shows the main inputs for Blackspot analysis. Historical fault information is currently gathered by LOCAMS, A51 and 'Sort' type programs. This I I I I I type of information will continue to be input to Personnel National user Information Organisational Support CSS although as fault rates reduce, its relations group (NUG) systems support development services importance will diminish. The current state of group (PRG) group (ISSG) group (ODG) plant information on the other hand will play I an increasingly important role. With the I : development of Line Test Systems (L TS} it will I I soon be possible to test each customer's line I Systems I every night and have the results analysed and available to engineering staff first thing in 1.. development ..1 -- Reporting group (SDG) the morning. The facilities that CSS is --- sign off specifying for line surveillance test systems- 13 can be summarised as follows Figure 3 • Test each customers line every night • Perform the following tests: F.M.O. disconnection insulation Battery B leg (BB) Battery A leg (BA) Fault docket Earth B leg (EB) Earth A leg (EA) LOCAMS A51 SORT Partial Short Circuit (PSC) Reverse Partial Short (RPS) • Classify defective lines service affecting class (1) disconnexion class (1) =than 20K contact non servicing affecting Blackspot Analysis Point class (2) between 20K and 52K (EPMC) contact class (3) between 52K and 11 OK and previously (1) or (2) class (4) not above 1M for 7 con­ secutive days since line classified as (1) (2) or (3) • Automatic output for Cable A1024 A1057 Quality LLIR/RLT Pressure all new service affecting faults Checks T.J.R. readings other associated class 2 and 3 faults • On demand printout for all faults faults by exchange area F.M.O. F.M.O. Supervisor Exchange Exchange faults by PCP/SCP faults by DP routing information readings will form the second major input to • Detailed Customer Report fault records from current state of plant information. including customer number, routing overnight tests summarised as follows:- details, fault details, fault history RCS reported faults • record flow readings termination details and special fault clears • maintain flow readings history conditions (SVI & CNI) reported faults • record pressure readings • Input information night routining faults • maintain pressure reading history New customer records Cable pressurisation and the automatic • show flow and pressure thresholds On site amendment or addition of monitoring of both flow and pressure • record and flag flow and pressure threshold 14 breakers • provide status reports for cabinet areas or Study Design Design Develop and test individual cables • provide exception reports for all transducers in an alarm condition • alarm summary- an extension of the ULSLSLSLSQ exceptions report which shows all alarms Statement of Statement of Performance Detail design Programs Subsystem for a given period and includes clear dates scope and limits feasible and design specifications configuration and times for those alarms cleared during SOFIORS design specification DDS and installation requirements PDS gu1de the period SDR • update trend report- records current readings and allows comparison with Acceptance previous reset values. The three remaining inputs, A 1024 (plant r------~ requiring attention), A 1057 (pair diversion Acceptance advice) and Quality checks will be used in the test plan CSS environment in essentially the same manner as they are used today in (EPMC) Blackspot analysis. ~-----~r-----~~1 V--J Training Figure 4 shows the stages through which User manual I each of the application areas progresses. Capture, collection, conversion The preparation and presentation of system Figure 4: Application/subsystem applications requirements has of necessity stages of development Conversion plan been formalised to ensure that all relevant areas have been investigated and all Requirement (SDR). SDRs translate the ORS intervals. Two trial Districts follow shortly interested parties consulted. A Product into a more detailed design requirements after Thameswey. The Project will be Review and Approval procedure lays down document. The CSS development is currently completed in all Districts in 1988. strict rules to be followed through each stage at the SDR and Performance and Designs CSS is far and away the biggest project of development. Specifications (PDS) stages. The NUG will ever undertaken by the business. We will all The Operational Requirements continue to work closely with the SDG be involved with it in the near future. Specification (ORS) is the first formal stage at through all stages of development including Providing the best possible service to our which all facilities are defined, agreed and preparation of user manuals, initial training customers is vital. CSS is the way ahead. confirmed by the NUG and 'signed off' by the and the formulation of the Conversion Plan. (01-242 9893 X 221) Consultative Panels. Because the project is so huge On completion of the ORS the NUG teams implementation will take place in four phases. begin to work very closely with the System The pilot District Thameswey, Design Group (SDG). The SDG is responsible (Reading/Guildford Areas) is due to start for the production of the next stage of the phase A implementation in July 1985 with development- the System Design phases B, C & D following at six monthly 15 Publie Utilities Streetworlls Aet of I950 - Wh~ it's being reviewed by David Trimmings LLS2.1.7 dramatically. The number of vehicles on the The House of Commons Select Committee In 1938 a joint Committee of the Houses of road has increased from 4.5 million to 20 on Transport during the 1982/83 Lords and Commons -the Carnock million. Similarly the utilities systems have Parliamentary session undertook an Committee- was established to consider the grown into a complex infra-structure of some examination of road maintenance. This original statutes of the utilities in relation to 1 ,650,000 kms underground mains, with a included public utilities works. Various bodies the procedures for breaking open streets replacement cost of £117,000m. It is an infra­ gave both written and oral evidence, much of and to make recommendations, taking structure upon which much of the nation's which was critical about the number of utility account of modern conditions. The Carnock standard of life and commercial success openings and the standards of reinstatement. Committee reported to Parliament in June depends but the system has to be continually In this evidence the National Joint Utilities 1939 and their recommendations provided maintained, refurbished, extended and Group (NJUG) suggested that many of the the framework for the Public Utilities repaired. This amounts annually to some 2 problems put to the Select Committee would Streetworks Act of 1950. The Act is in four million small openings and the installation of be overcome if all highway authorities were parts over 18,000 kms of new mains. to enter the model agreement with the • The Street Works Code which regulates the A major difficulty was that although the Act utilities. exercise of the utilities statutory powers to obliges utilities to carry out reinstatement to In their Report, the Select Committee work in streets the reasonable satisfaction of highway concluded 'There is clearly considerable • A code to govern the relations between authorities, the Act itself did not provide an room for improving the standards of trench utilities and highway authorities where agreed standard of reinstatement. In 197 4 reinstatements. We hope that through the roadworks affect utilities' apparatus the PUSWA Conference, which is a PUSWA Conference the highway authorities • A minimum code regulating the relations representative body of the utilities, highway and public utilities will be able to reach an between the utilities themselves authorities and the Department of Transport, agreement on procedures and standards • deals with enforcement, interpretation, produced a 'Model Agreement and which is fair to both sides. If provisions within financial and general provisions and Specifications' for reinstatements under the 1950 Act prevent such an agreement application in London and Scotland. PUSWA. One of the main aims of the from being reached, the Act should be There is no doubt that the Act is complex and document is to enable the utility or its amended.' In her evidence to the Select often difficult to interpret other than by contractor to carry out the permanent Committee, Mrs Chalker indicated that lawyers. It was therefore important to reinstatement themselves; thereby avoiding although she did not rule out the possibility of produce a 'layman's guide'. This was the often lengthy delays which occur before legislation resulting from the review of published in 1972 by the Department of the authorities who have elected to do so carry PUSWA 1950, she would prefer, if possible, to Environment entitled- 'Guide to the Public out permanent reinstatement. Unfortunately, obtain voluntary agreement between the Utilities Street Works Act 1950'. only half of the highway authorities in the parties. In the 34 years since PUSWA was enacted country have so far entered the Model Early in 1984, Mrs Lynda Chalker, M.P., the street works environment has changed Agreement. Minister of Transport announced in 16 Parliament that she had decided that a The NJUG submission is in three parts. industries, the utilities have no freedom in review would be carried out of the Public Part 1 deals with evidence and covers 104 deciding whether or not to provide and Utilities Street Works Act 1950 and the Model pages. It sets out the NJUG views and makes maintain a supply or service to the public; Agreement and Specifications 197 4. recommendations to the Review Committee. they are statutorily obliged to do so. The Review is currently being undertaken Part 2 contains complementary evidence in It would be presumptive to speculate what by a three man team. Its Chairman is the form of appendices and covers a further the outcome of the Review is likely to be. Professor Home OBE, FRS, P.Eng, formerly 152 pages. Lastly Part 3 deals with 17 What one can say is that the theme of the Professor of Civil Engineering, Manchester exhibits submitted to the Review. Details of NJlJG submission is the efficient and University. Mr N GEllis, OBE, P.Eng, FICE, the NJUG evidence will not be available until responsible use of public money, for whether FIHT, formerly County Surveyor, South Professor Horne's report is published by the it is utility or highway authority expenditure it Yorkshire and Mr D V Ford, C.Eng, FlEE, Department of Transport later this year. must be used to the optimum benefit of all. formerly Head of Distribution Engineering, In addition to taking written evidence, Acknowledgements to Secretary, The Electricity Council. Professor Horne and his colleagues have 'National Joint Utilities Group' It is inevitable that with such a large work taken oral evidence and have also had load disagreement between utilities and detailed discussions with the utilities and the highway authorities is likely to occur. highway authorities. During the early part of Professor Horne and his team have therefore the Review the team also made a number of been asked to carry out their review in the technical visits to obtain first hand light of present day circumstances. Their experience of street works. These visits were terms of reference also include examination rated by the utilities and the highway of the safety of workmen and other road authorities. users, liaison arrangements, the impact of They included particular visits to the cable television and utility mapping. Dudley Digital Records Trial, the Lothian One­ The investigation commenced in February Call Trial and to the British Gas, Engineering 1984 and interested parties were invited to Research Station in Newcastle, where a vast submit written evidence by April of that year. amount of research and development work is It was decided by the member utilities of being undertaken on road excavation and NJUG not to make individual submissions but reinstatement. to be party to one composite NJUG It is in the context of this background that, submission. This was prepared by a joint a 34 year old Act of Parliament, is under utility team who had been seconded away review. However, it is often forgotten that the from their normal duties to deal with the utilities rights to break open streets goes PUSWA review. back to the mid-19th century. Unlike other 17 Conafort (EJ TXE4 eonaputer aids to maintenance by Graham Mitchell LES1.5.3 Note that its implementation is subject to into a wide range of categories. These COMFORT(E), COmputerised agreement between the POEU and local facilities could eventually eliminate the need Maintenance FOR Telephone Exchanges, management. The program will not be for a paper fault docket. A basic docket is a collection of computer programs to available for use on TXE4A until the Standard analysis program should be available soon. assist in the maintenance and Times for routines, faulting and management of TXE4(RD) and TXE4A miscellaneous tasks have been specified. Exchange records exchanges. The programs are being This program provides a very rapid access to developed to operate on the OPE standard Pate 4 the subscriber records database for range of single-user Small Business This program enables fault printout from TXE4(RD) exchanges using a variety of Computers (SBC's) and the BT Factories TXE4(RD) and TXE4A exchanges to be enquiry entry points eg Directory Number, Multi-User Multi-Processor (MUMPS) analysed locally. The program is widely used Equipment Number, Rack & Line Cct and machine. throughout the country with a considerable MDF bar & pair. The database used is that It is intended that program development degree of success. The lack of easy access developed by traffic and construction and implementation follow a series of to SBC's prevent some sites from obtaining programs during the design and installation logical steps with the objective of the full benefits of the program. Data transfer phases. The subscribers data on the 156mS providing maximum support to TXE4 from the exchange to the SBC currently may scan can be examined and updated. The exchange maintenance. be direct (online), by means of paper tape contents of the Cyclic Store may be The programs currently available or which is cumbersome and error prone, or by compared with the records database base planned are listed and described below. magnetic tape. The use of magnetic tapes for using the WAM (Tester 229) output which data transfer requires a small modification to may be transferred to the computer online or Work scheduling the exchange interface. This small via paper or magnetic tape. A utility program This program provides a method of modification provides the facilities for high is available to enable the exchange database estimating, planning and controlling work speed fault printout and is essential to obtain to be generated using the WAM tester output. carried out by exchange maintenance staff the full benefits from other programs. The This utility can be used for exchanges which based on the use of Standard Times. The development of the program is complete were brought into service before the traffic facilities enable manpower resources to be except for the investigation of any apparent and construction programs were available. matched with the work required in an sofware bugs discovered in the field. • Programs that provide enquiry and updating exchange as determined by local facilities for the TXE4A's subscribers management. Programs and documentation Local docket analysis database are being developed now and have been completed for TXE4(RD), TXE2, Brief Description. This program enables should be available soon. TXK1, TXK3 and some Strowger exchanges. TXE4(RD) or TXE4A fault docket information • No database enquiry program exists for The scheme was field trialled in the Aberdeen to be keyed in via the VDU terminal and equipment which appears on the 36mS and Area and is now available for national use. contains facilities for retrieval and analysis 12mS scans of the Cyclic Store, eg 18 Materials and eonaponents eentre naakes its naove equipment such as 0/G junctions etc. An onstatie enquiry program for these scans in addition to the enquiry program for subscribers by Trevor Morton-Holmes MC1.5 discharges applied to an input pin of a micro­ scans would go further towards eliminating Modern electronic components and processor. You could do the same by the needs for paper records. A feasibility systems are susceptible to electrostatic touching that same pin and would not know study has been carried out to see what discharge (ESD) or 'zap' problems. it! other information could be recorded and Previously it had been thought only Metal Detailed studies have shown that the only the structure of the appropriate database Oxide Semiconductor (MOS) technology effective way to control the static discharge but this has not been finalised to date. devices were at risk, but from work from the human body is by equipotential performed within BT it is now proven that bonding using a wrist strap and cord to the Service and performance the majority of semiconductor devices, equipment receiving attention. It is not This program processes several cost and and indeed some modern technology necessary, in this context, for the cord to be service indicators and compares them with passive components, can be degraded, earthed, but only for man and machine to be locally set targets. The idea is to combine even if not instantly destroyed. The trend at the same ambient electrostatic potential. certain indicators and produce exception towards smaller device geometries, to In common with the computing, reports as required. A demonstration achieve a lower (speed x power) product, electronics and the telecommunications program has been written but future will lead to increased vulnerability, as the industry generally, BT has recognised the development is not anticipated. on-chip protection circuits have very cost benefits afforded by an ESD awareness If you require any further information limited capacity to prevent damage from campaign and the Materials and Components regarding any of the programs above or the ESD type events. Components mounted Centre in conjunction with Tools Group hardware required to run any of the programs on PCB's are just as vulnerable as the LLS2.3.4 has developed a range of contact your District (or Regional) TXE4 unmounted device, and in some cases the electrostatic protection (ESP) items which are Maintenance Support Group. risk of damage is increased. now available through the Vocabulary of (01-432 2388) One of the more significant sources of Engineering Stores, (section 5T-B for all items static fields is the human body, where under except Bags Static Shield which are in certain conditions, static voltages exceeding Section 8M-B). Details of ESP items and their 30,000 volts can be developed. use in typical situations are available in a The human body threshold of feeling on booklet entitled 'British Telecom Electrostatic discharge is around 5000 volts, yet Protection' available from LLS2.3.4, Room semiconductor components can be 1432, 207 Old Street, London EC1 V 9PS. degraded by zaps of less than 100 volts. Many commercially available products are The photograph shows the catastrophic on the market but their use by BT staff is not damage caused by two 500 Volt electrostatic recommended. The BT range has been - 19 designed to provide highly controlled static An ESD module is included on BT a full range of laboratory facilities and bleed off times. electronic equipment training courses and an services available to support staff involved The range is manufactured to a standard ESP 'user guide' will be available to with ESD, Electromagnetic Compatability of quality and reliability which we are managers in September for use as local (EMC) and related problems. On site confident will encourage a high level of user instructions or procedures. Clearly situations investigations of problem situations or acceptability. Large contracts have been will arise which will not be covered by the installations can be undertaken if required. placed with reputable UK manufacturers currently available information, but MCC will For further information please contact leading to considerable cost advantages to be pleased to help with any technical or John Lee on 021-708 1111 Ext 267 or Chris BT. It is intended that quantities will be procedural advice. Wynne-Davies on 266. sufficient for individual tool kit issue for all BT The Materials and Components Centre has (021-708 1111 Ext 266) staff mvolved with 'handling' electronic equipment. Catastrophic damage on a microprocessor input pin which has ESP bonding points are also gradually received two separate 500V ESD zaps. Magnification 3000X. being introduced on BT systems for the direct connection of ESP cords during installation or service activities. It is vital that contract deliveries of electronic equipment and components are free from electrical overstress by static discharge and BT is ensuring that correct procedures are carried out by contractors and that the finished product is correctly packaged in static shielded or safe materials. A range of static shielding bags has been introduced for use within the business and it is equally important that all personnel involved with the 'handling' of electronic items are aware of the correct precautions so that systems realise their designed 'in service' lifetimes. To help promote the principles of good ESP precautions and practices and to explain fundamental concepts involved, MCC has produced a short 'ESD Awareness' video film which is available for purchase in either VHS or U-matic format. ESD awareness seminars can also be arranged, tailored to be suitable, and entertaining, for staff at all levels in every part of the business. 20 Statie eleetrieit~ and digital equipnaent

by George Clark TS02.1.3 Equipment Discharge volts possible to design equipment that is The previous article has dealt with the work applied to rack unaffected by static discharge it would be an that the Materials and Components Centre 2kV 4kV 6kV expensive operation. Fortunately the has carried out in identifying the need to preventive measures already devised for protect electronic components from the EDL 140 Errors Loss of protection at component level are equally effects of electrostatic discharges. This synch effective in preventing static discharges from article looks at the problems caused by EDM 6000 Errors Loss of reaching equipment. electrostatic discharges in digital repeater 2/8 Mbit/s synch These preventive measures are the use of and switching units and the precautions a conductive wrist strap and high resistance required to prevent discharges affecting EDM 6001 Errors Loss of connecting cord to connect a person to an equipments. 8/34 Mbit/s synch identified point on equipments. On connection any charge on the person The problem EDM 6002 Loss of will dissipate slowly to bring equipment and 34/140 Mbit/s synch Electrostatic discharges are responsible for body to the same potential. This protection two serious problems in digital units. will continue as long as the connection is • The first, and probably the best known, is This is by no means a comprehensive list of maintained. component damage (see previous article). It affected equipments. It would be reasonable This method of protection is known as should be noted that most current to assume ALL digital equipment is equipotential bonding. electronic components can suffer damage susceptible to interference. On BT equipment the position of the from electrostatic discharges even when Note that a discharge of approximately discharge points will be prominently mounted on printed circuit boards. 4kV is just perceptible to a person as a identified. The position of the point may vary • Of equal importance, in an operational slight shock and a discharge of from equipmentto equipment to minimise station, is the problem of electrostatically approximately 7kV is required to produce interference effects. induced interference. Interference results a spark. It is essential that only the identified in corruption of data and will thus affect the Typically voltages in the range 2kV to more bonding point is used. service seen by our customers. The than 1OkV can be generated by a person Similar application of the principle of following test results illustrate the walking. The actual voltage depends upon a equipotential bonding, together with the use interference effects for digital transmission number of factors such as floor material, of anti-static bags and packing material will equipment. clothes worn, humidity etc. be used to protect spare units in storage and faulty units during transit between site and The solution repair centres. At present we can do little to prevent the These preventive measures are being generation of static charge and although it is introduced as quickly as possible into units- 21 Call sending eapallilit~ for the 0/G Junetion Routiner controlled by LCS and NN. The necessary by George Gaffney ES37 the routiner. instruction to implement these measures is Stoke on Trent Area The auxiliary test unit uses the BT Sceptre currently with Unit Managers and District If you are responsible for the maintenance of 100 telephone as its memory store and Specialists. a TXS exchange that already has an 0/G pulsing element. The test sequencing and It is contained in junction routiner, then this is for you, read on. routiner stepping is undertaken by a solid Operations and Maintenance Guides, In the unmodified state the routiner state logic control board. DMSU Maintenance Note No 38, and (diagrams AT 5255 and AT 5131 refer) was The facilities are: the booklet 'Take precautions. designed to test two wire loop-disconnect • on completion of the normal test sequence Electrostatic Interference junctions for continuity, polarity, and balance the routiner hands control to the auxiliary Costs Us Money' as far as the incoming selector or relay set at test unit if the auxiliary test key is operated. the distant exchange. It took no account of If the key is normal testing proceeds as if The latter booklet is currently being issued any outgoing relay set or the ability to dial the auxiliary test unit were not fitted. to all LCS and TS staff working on digital over the junction. When it was designed tin • seizure of the 0/G relay set, if one is equipment. For further information on ESD 1957 two wire loop-disconnect junctions provided, or the distant selector or relay problems and on the proposed methods of predominated in the local network and there set, and testing for continuity and polarity reducing the effects of discharge contact: was a need for a routiner of this type. During up to the first transmission bridge. • Your Unit Managers the last twenty-five years a number of • sending a number of up to 16 digits to an • Your District Specialist. different signalling systems have been ordinary test number at or through the • DMSU Maintenance. Steve Barber introduced to the local network which cannot distant exchange. TS02.3.5 01-432 9168. be tested by this routiner. • monitoring for receipt of any meter pulses, • NN Switching Maintenance. (except DMSU) A modification seeks to overcome the line reversals or tones received. Brian Harris TS02.2.1 01-432 9178. shortcomings of the routiner by allowing it to • if the pre-programmed combination of • NN Transmission Maintenance. George make tests through an outgoing relay set, meter pulses, reversals, and three bursts of Clark TS02.1.3 01-432 1328. irrespective of the signalling system used, 400Hz test tone are received a test finish • LCS Digital Switching Maintenance. George and after proving continuity and polarity, to signal hands control of the routiner back to Huggins LES4.2.2 01-432 9412. send up to sixteen digits to a test number and the normal test unit. • LCS Transmission Maintenance. Mike interpret the results of the call. This is • to generate an alarm and if on automatic Howard LLS2.6.5 01-250 6036. achieved by inhibiting the test finish signal control, initiate docket print, under any of (01-432 1328) after completion of the normal tests, which the following conditions are still applied, and diverting into an auxiliary -failure of line continuity. test unit the P, positive and negative wires. -polarity reversal on seizure. After completion of the tests applied by the -receipt of NU tone after sending. auxiliary test unit, control is returned to -non-receipt of a meter pulse if pro- 22 grammed to expect one. -non-receipt of a reversal if program­ med to expect one. -non-receipt of test tone. • if the routiner is under automatic control abandonment of the routine cycle if three to five (pre-programmed) fault dockets are initiated during any routine cycle. This prevents continuously ringing a customer under faulty routing conditions and the printing of useless dockets in the event of a junction cable fault. • rejection of meter pulses of less than 11 OmS duration. • on manual control only, the ability to check for subsequent meter pulses on MOJ routes, with the display on the Sceptre telephone displaying the time in seconds Cost Conclusion since receipt of the initial meter pulse. The two PCB's and associated components MAC sequence results are being subjected to cost around £70. Mounting the components even more stringent targets. If further Results and routiner modification is approximately improvements are to be obtained it is The modification was first applied at a 7000 sixty hours work. The greater cost is incurred necessary to identify faulty circuits and line, RND exchange. There are 260 junctions, in re-routing the routiner access from the TJF equipment at an early stage, preferably including level one, all connected to the to the IDF and in providing the IDF jumpers. before becoming service affecting. This routiner. From the date of implementation The amount of work depending on the size of modification allows for all 0/G junctions, from there has been a steady improvement in PD, the access and the number of junctions, this a medium sized exchange, to be tested every PE and WC on MAC measurement will obviously vary considerably from one twenty-four hours and problems quickly sequences 2, 3 and 4. exchange to another. identified. It is also possible to use the One unexpected bonus has been the routiner during the day to send test calls over number of barretters found to be out of Circuit design each junction in turn on any selected route. A balance. Listening tests showed that relay The circuit was designed by Roger White, TO very useful facility when customers report sets failing the balance test were subject to at Rugeley exchange. He also constructed difficulty in dialling a specific destination. line noise caused by mains hum. The level of the prototype and produced the artwork for Regular use of the modified routiner can only noise dependant on the calling customers the PCB's used in the area standard result in an improvement to the service given line conditions. It is also possible that those modification. The photograph shows the to ou~ customers. barretters that are high resistance on one Sceptre telephone and PCB's mounted at the (0785 57340) element, may be the ones that will go open top of the routiner rack. The perspex front circuit in the near future. cover has been removed for clarity. 23 Integrated serviees digital networll (ISDN)-the networll of the future by Colin Haworth and Alan Cook limited set of non-voice services such as communication needs, whether for voice or LCS/NSD 3.1 .5 Datel and Prestel. However the inherent data services. This is achieved by extending This article presents an introduction to a constraints present in the analogue network the ION to the customer, by means of major development in make it increasingly unsuitable for emerging Integrated Digital Access (IDA), thus creating telecommunications which will profoundly data transmission applications. This has been the ISDN (figure 1). affect communications in the UK over the partly overcome by the introduction of Telephony accounts for most of BT's next decade. service dedicated networks such as the current income but the rapidly expanding Packet Switched Network and Kilo Stream. demand for data services will drastically The Integrated digital network change this position, and BT must be able to British Telecom is currently modernising the The need for an ISDN respond to market requirements. The Public Switched Telephone Network (PSTN) Although the ION will greatly improve the creation of dedicated networks to carry these with the provision of the Integrated Digital quality of service which the PSTN provides, services is an expensive proposition. What is Network (ION). The ION is based upon the real benefits of a digital network will only needed is a general purpose network to processor controlled digital System X be realised when digital working is extended which comparatively small enhancements exchanges interconnected with digital to the customers premises and when the may be made in order to support new transmission and supported by fast customer is given the capability to utilize the services as they arise. The ISDN is such a interprocessor common channel signalling. digital network to wholly satisfy his network. The ION wil provide a wholly digital connection (circuit switched at 64 kbit/s) Figure 1 between all digital local exchanges. The conventional telephone network found in most countries, including the UK, is based primarily upon analogue transmission and switching with restricted signalling capability. This results in a network in which a national call takes between 5-25 seconds to set up, and establishes a transmission path of 3kHz bandwidth with an ill defined delay and attenuation characteristic. The latter places severe restrictions on the speed at which data can be transmitted. Despite these limitations the PSTN has been used to support both telephony and a 24 The ISDN is aimed initially at business full duplex digital transmission system Note that the D channel provides the customers using modern office which operates over the customer's normal signalling for both the B and B' channels and communications equipment but the 2 wire local line to the exchange. The three carries call progress information by means of continued market growth of such devices as channels making up the 80 kbit/s IDA DASS. home computers and videotext will make the connection are shown in Table 1. ISDN attractive to the residential market too. Table 1 • Multi-line IDA provides up to thirty 64 kbit/s traffic channels (exchange connections) Integrated digital access Channel Channel Usage carried on a 2 Mbit/s digital path. Separate The creation of the ISDN hinges on the Designation Rate 64 kbit/s channels are allocated within the 2 provision of a digital link between the B 64 kbit/s Voice or data Mbit/s for signalling and parity/ customer's premises and the digital local B' 8 kbit/s Data synchronisation. The principal initial use of exchange, known as IDA. Two forms of IDA D 8 kbit/s Signalling this type of access is expected to be the have been developed; single-line IDA and connection of digital PBXs to the ISDN, thus multi-line IDA (figure 2). • Single-Line IDA provides the customer with two traffic channels (exchange connections), each with a different directory number. One traffic channel can 6::+-t---- carry voice or data at rates up to 64 kbit/s } { SIG whilst the other traffic channel can carry NTE data at .rates up to 8 kbit/s. Both traffic channels can be used independently and at the same time. (At the exchange, the 8 kbit/s traffic channel is rate adapted by reiteration to 64 kbit/s for transmission through the ION.) In the customer's Digital IDA local premises a Network Terminating Equipment 80 kbit/s 8k MUX exchange (NTE) provides the customer with standard } over 2 Mbit/s interfaces for the terminal equipment. SIG local Among the many functions that the NTE r cable NTE performs is the multiplexing of the two pair traffic channels (64 kbit/s and 8 kbit/s) along with an 8 kbit/s signalling channel (total 80 kbit/s). This signalling channel contains the signalling information of both traffic channels. The signalling system employed PBX is specific to IDA and is known as the or NTU 1----~ Digital Access Signalling System (DASS). ISPBX The NTE also provides the interface to the Figure2 - 25 permitting the provision of the ISDN kbit/s and 8 kbit/s traffic channels), the NTE National ISDN capability to the extensions of that PBX. resolves contention between them, acting The pilot ISDN service is the nucleus on Such a PBX is known as an Integrated as a traffic concentrator. which the National ISDN will grow. All the Services PBX (ISPBX). The multi-line IDA For the next phase of ISDN a new cost digital local exchanges being purchased by connection is terminated at the customers reduced NTE (NTE 4) is being developed BT have the inherent capability to terminate premises on a Network Terminating Unit which will incorporate new internationally both single-line IDA and multi-line IDA. (NTU). agreed rate adaption techniques and will be A decision to include IDA line equipment in a data only NTE offering two X21 ports. To the normal planning, dimensioning and IDA multiplexor (IDAMUX) facilitate interworking to V-series terminals ordering procedures for digital exchanges will In exceptional circumstances single line and to provide a telephony capability, a come after gaining marketing and operational IDA can be provided to customers in range of terminal adaptors is being experience from the pilot service. In the exchange areas still served by analogue developed to connect onto the X21 port of mean time, IDA line equipment, IDA exchange equipment by means of an IDA the NTE4. multiplexors and NTE's will be purchased and multiplexor. This multiplexor extends single controlled by LCS/HQ. Each Area or District The pilot ISDN service line IDA connections for up to 15 will provide IDA service based on their customers to the nearest most appropriate In order to gain experience on the digital local exchange over a 2 Mbit/s digital technological development and operational aspects of providing a National ISDN, and path (figure 2). To MUX sites in to stimulate interest in ISDN amongst Cheetham Hill Alderley Edge / Network terminating equipment (NTE) customers and terminal equipment Altrincham, Two types of NTE have been developed for suppliers BT is implementing a pilot ISDN Trafford, the Pilot ISDN service. The NTE1 is a desk service based on four System X digital local Bootie top instrument which includes a digital exchanges (two in London, one each in '-._"'-. Wythenshawe telephone, keypad, display and a single Birmingham and Manchester). The pilot 1 data port. This data port can be configured ISDN service is not a field trial but the first -..~East to operate over the 8 kbit/s or 64 kbit/s step towards providing a National ISDN Warrington Central Blackfriars 831/3 traffic channel to the exchange. The other service. type of NTE, the NTE3, is a wall or shelf The pilot ISDN service includes provision mounted device designed for applications of 1000 single-line IDA connections and 40 Wolverhampton where there are a number of different multi-line IDA connections spread equally West Bromwich terminal equipments requiring access to over the four System X digital local Erdington BM Central the network and which are all capable of exchanges. The majority of the single-line controlling call set up procedures. This NTE IDA connections will be to out-of-area has no built in telephone, keypad or display, locations, served by IDAMUX's parented on but has six terminal ports each of which these System X exchanges. By the use of may be configured to support various types these multiplexors a reasonably large Edgbaston of terminal equipment. Because no more geographical area of the UK, covering the than two of the six data ports may be major business centres, will be included Warwick connected to the exchange at one time (64 within the pilot service (figure 3). 26 CoventGdn Southbank Baynard 489

1Croydon

- 27 market forecasts by making use of these central stocks of equipment and installing the The derived serviees equipment by Direct Labour. During this time and beyond, there will be a program of enhancements to provide networ• • new ranges of NTE by Dave Baker NNITSO 2.2.1 services may be offered in the future and to •links between the ISDN and dedicated data Introduction cater for these additional NNG codes have networks In June 1982 a Task Group was set up within been reserved. • new supplementary services Head Office to investigate what action should • enhanced network facility be taken to overcome the shortage of BT will also implement international • Linkline 0800 National Numbering Group (NNG) codes to This facility is very similar to the existing standards appropriate to ISDN as and when provide for Derived Services. The Freefone facility with the exception that it is these are agreed. An example being the recommendations were published in August fully automatic and operator assistance is not introduction of 144 kbit/s single line IDA (as 1982 which while acknowledging that the required. The caller dials a six digit number compared with 80 kbit/s single line IDA) more elegant solution would be to add a preceded by access code 0800 and is which will provide for two 64 kbit/s traffic Derived Services Switching function to automatically routed to the appropriate channels. selected Digital Main Switching Units the answering point. As with the current Freefone relatively long lead time precluded the use of service the renter, called the Service ISDNIIDA Maintenance this method. Provider, pays for the call charge and not the ISDN equipment such as the multiplexors The method recommended, and finally caller. and the 2 Mbit/s digital path are continuously adopted, was to provide an overlay network monitored allowing BT to identify and rectify using existing Type 14 Register Translators • Linkline 0345 faults rapidly, in many cases before the as the controlling equipment and recovered Again the caller dials a six digit number but customer is even aware of the fault. With the Strowger switching equipment. It was this time preceded by access code 0345 and introduction of IDA the local line from the envisaged at that time that the function of is automatically routed to the appropriate NTE to the local digital exchange (or handling Derived Services traffic would answering point. In this case however the multiplexor) can now undergo automatic eventually be taken over by System X as the caller only pays a local charge (at Peak, testing from the exchange at regular digital network evolved. However, because of Standard or Cheap rate) and the Service intervals, possibly at night. Faults causing the forecast in the growth of traffic it has now Provider pays the difference between the loss of transmission and/or signalling are been decided to retain the overlay network local call charge and the total cost of the call. automatically identified and reported to the and replace the analogue Derived Services appropriate BT maintenance centre. Switching Centres (DSSC's) with digital The NTE can support exchange based • Universal Access Number centres in 1987. A facility that may be attractive to some testing even if the customer has switched off organisations is Universal Access. This the NTE mains power, minor faults not Services enables Service Providers to advertise one detected by automatic means will rely on the The services that will initially be provided by number nationally and have up to eight local customer fault reporting in the normal way. the Derived Services Network (DSN) are answering points, that is one in each DSSC (01-432 2291) Linkline 0800 and Linkline 0345. Other catchment area. This is achieved by 28 arranging for controlling equipment at each Provider in the normal way from a Final DSSC to give a local routing translation to the Selector. When the called Service Provider national number dialled. The facility can be answers, ringing is tripped, and the Service offered on Linkline 0345. Provider answer signal is extended back to the contolling Type 14 Register Translator The Derived Services Network equipment. If the call is a Freefone call the The analogue DSN will consist of eight fully • Derived services Service Provider answer is suppressed at the inter-connected DSSC's each with their own switching centres originating DSSC. If it is a chargeable call the catchment area. The location of the eight & Data collection Service Provider answer signal is extended DSSC's will be centre back to the MSU to initiate local call -london covering London area charging. -Guildford covering S.E. except London -Bristol covering S.W. and S. Wales Derived Services Switching Centres -Cambridge covering East Anglia Each DSSC will use three main types of -Birmingham covering Midlands hardware -Manchester covering N.W., N. Wales and -strowger switching equipment. N. Ireland -Type 14 Register Translator Access -Leeds covering N.E. equipment. -Glasgow covering Scotland -call logging equipment. Access to each DSSC will be via Main • Strowger switching equipment Switching Units (MSU's) within each The switchblock will, in the main, consist of catchment area. Smaller MSU's which recovered Strowger equipment refurbished to cannot justify a direct route will gain access an acceptable standard. Where the demands via larger MSU's. for Strowger equipment cannot be met by re­ Routing of calls use, then new equipment has been ordered The Derived Services Network is only Figure 1: DSSC Catchment areas from the manufacturers. designed to handle incoming calls and The switchblock comprises three Group cannot be used to make outgoing calls. of the Service Provider. The Type 14 Register Selector stages (D1st's, D2nd's and D3rd's) A Derived Services call is handled in the Translator gives an appropriate routing and a Final Selector stage. Each unit is fully normal way by way of the local exchange to translation and the call is switched to the self contained incorporating its own common the MSU, where the charge rate is Service Provider through the switchblock or if equipment, Ringing Apparatus, Alarm Control determined, and the call is extended to the the Service Provider is in a distant catchment racks, and so on. All standard Strowger local DSSC. The whole number minus the area the call will be routed to the appropriate exchange support equipment such as Trunk initial "0" is passed to the DSSC where it is DSSC. Trunks from distant DSSC's terminate and Junction Routiners, Traffic Recorders, examined by the Type 14 Register Translator on incoming 1st Selectors and the routing Special Faults telephone and Test numbers, to determine firstly, whether it is a chargeable digits received from the distant DSSC switch are provided to ensure all maintenance or non-chargeable call (for example 0345 or the call to the required Se~vice Provider. procedures can be carried out to maintain 0800) and secondly, to determine the location Ringing current is sent to the Service the efficiency of the unit. _. 29 • Type 14 Register Translator equipment The Type 14 Register Translator installation at each DSSC will consist of a minimum of two ~~ processor racks and a number of Register Access Circuit (RAC) racks. Processors are Calling Customer's Telephone Local Exchange Trunk Exchange connected in a ring with left and right highways connected to adjacent processors NB Each of the Answering Points so that data is constantly being compared by will require its own set of circuits to link it to the local DSSC. adjacent processors and any discrepancies are output to a teletypewriter. Two teletypewriters are provided on each Link ~---D-ed-ic-a~ted processor ring; the remote fault teletypewriter receives all print output from the system whilst the service teletypewriter is Customer's Answering Point Derived Services Switching Centre used for general man-machine communications, including RAC routiner Figure 2: Call routing From control and system faulting. other Type 14 Register Translators are already in Incoming calls DSSC's use at Central SWitching Units in the Public from catchment area MSU's To Switched Telephone Network (PSTN) and other have proved to be very reliable in service. DSSC's The main differences of the DSN version to Type 14 the PSTN version are register Large -store capacity of DSN version has been translator t---- SP's increased from 64K to 128K words so to Call increase the code expansion and routing logging store capacity of the processor. -RAC Routiner added. -No MF capabilities. -Different applications software. A more detailed description of the Type 14 Medium & Register Translator is given in Maintenance -small News No. 20. Data SP's Register Access Circuits, although collection Strowger developed a number of years ago for use in centre switchblock group the PSTN, were never utilised and are being selectors used for the first time in the DSN. Figure 3: DSSC Equipment D 1st, D 2nd, D 3rd Each RAC rack houses 128 RAC's and 30 Test desk Equipt CAMSS AC9 10% lnter-DSSC terminal -~ test lh access junctions ------, I I Test I AC14, AC15 Service _,....._ selector Ih provider SP I l circuits I I Controller Other termi nals I I I ""' I I I

•I: Service l provider : .., I testing I I & I Teletype I busying I L-----'

TJF

CAMSS computer Data link f----+---- Other terminals Central 9-6 data ~------lf---1 Modem I---f base

Figure 4: DSN-TMCC organisation -31 associated equipment including Access is collated by the Host computer, transferred Fault Reporting and Testing Switches. The two-stage Access Switches, to magnetic tape and sent to the National arrangements maximum of 16 per rack, are graded Billing Centres for preparation of Service Each DSSC will have associated with it a crosspoints connecting RAG's to Signal Provider bills. As all information of all calls is Derived Services Network Fault Reporting Conversion Circuits (SCC's) on the processor contained on the data records, use can be Point (DSNFRP). All amplified Service rack. The RAC itself is a microprocessor made of this to provide Management and Provider circuits will be routed through Test controlled circuit which can be strapped on Traffic statistics and also call statistics. Jack Frames to enable faulty circuits to be each circuit edge connector to give the tested quickly and busied if necessary. All required supervisory conditions, that is partial Service Providers other circuits will be accessed using either a or full supervisory, 2 or 3 wire access. It acts Service Providers are divided into three Trunk Test Final Selector or Ordinary Test as an interface between the line and the Type categories: High user, Medium user and Low Final Selector for 2/10 and 11/- circuits. 14 Register Translator equipment and user and these categories are related to the The Test Desk connected to the DSN FRP provides a transmission bridge and 'clean' type of access provided will be used for Service Provider fault pulsing-out circuit. On the outgoing side each • High user Group Selector level (DDI or non- reporting, administration and control. A RAC is associated with its own D1st Selector DOl) Freefone Universal Access Number 0800 in the Strowger switchblock. • Medium user 11/- Final Selector level 1100 has been provided for this purpose and • Call logging equipment • Low user 2/10 Final Selector level also a number of additional freefone lines The Call Logging Equipment (CLE) is a Each non-DOl Service Provider will terminate have been provided for engineering use. proprietary system which has been enhanced on a subscribers uniselector circuit within the Service Provider details, fault history and to meet the requirements of BT for a billing DSSC. Outlets of the uniselector are so on will be entered onto a centralised· and network management system in the connected to a Service Provider Line Test database and for this the Computer Aided DSN. Circuit (SPLTC) which when seized by the Maintenance for Special Services (CAMSS) The DSSC equipment consists of call Service Provider will return continuous will be used. Access to CAMSS will be logging equipment (SRS 2020A) which is ringing tone. This facility enables Service provided by means of a terminal. This will connected to the -ve, +ve and TCSJeads of Providers to check that communication with enable Service Provider faults to be all RAG's and records all details of the call, the DSSC is possible. progressed quickly and efficiently, enable the number dialled, time of call, duration of call, Service Providers using Director Exchange status of any Service Provider in the country and so on. Each SRS 2020A can monitor 400 Line (DEL) accessing principles may be to be ascertained immediately and enable circuits. The Service Provider answer signal accessed from the DSSC by means of a Service Provider fault statistics to be is monitored on the TCS lead to determine direct 2 wire circuit to their premises produced., when call charging should start and finish. provided they are situated within the (01-432 9037) When the call has finished the SRS 2020A unamplified signalling system limits. transfers all the information to a data store However, as DSSC catchment areas are (PDU 20) where it is stored on disc. large many Service Providers will require the At pre-determined intervals during the day use of amplified signalling systems. Initially the data stored on the disc is transferred over this will be catered for by the use of SSAC14 a data link to the Data Collection Centre or SSAC15C and eventually SSAC15E. (DCC) at Oswestry, Shropshire. Here the data

32 Optieal eonneetors used on proprietar~ and standard optiealline s~stenas by B. Plummer NNfTS02.1.1 maintenance hazard. The problems have Connector care Optical connectors provide a flexible method been caused by incorrect handling during It is most important that optical connectors of interconnecting optical fibre ends to one maintenance and, with some connectors, are handled as little as possible and with another, enabling internal and external weaknesses in their design. extreme care, and should be kept clinically maintenance activities such as replacing an The first three orders placed by BT were clean. Before de-coupling an optical optical equipment card, or cable fault for Proprietary Optical Line Systems (POLS) connector, the LED or LASER transmitter on location, to be performed with greater ease. utilising equipment made to the manufacture the fibre must be de-activated, by removing They are analogous to their coaxial specifications. This has resulted in a variety the appropriate card or its power supply or counterparts in so far as the application is of optical connectors being used, each power feed unit for dependant regenerators. much the same but, whilst they may look like employing different techniques to perform the When the connector is decoupled it should a coaxial connector, the physical differences same task and therefore requiring different immediately be checked with an Optical are in fact profound. Optical connectors need terminating procedures. Further orders for Power Meter to ensure no light is being to align glass-fibre cores of between 7 and 50 Standard Optical Systems (SOS) made to BT transmitted. micrometres (one-thousandth of a millimetre) specifications have been made, mainly of the Unless they are to be used immediately, and are thus very high precision devices single-mode 140 Mbit/s variety for the trunk the connectors and open ends of couplers which have to be handled with great care. network, and for these a standard connector should be protected with clean dust-caps. If Optical connectors could be described as a (Connector Optical Fibre no. 4A) will duskaps are unavailable the connector necessary evil as they are easily damaged eventually be used. should be enclosed in a small clean and have proved on many occasions to be a polythene bag sealed with an elastic band or adhesive tape. Never touch the end face of Table 1 Types of connector In use the connector. Do not let optical connectors lie on the Manufacturer Proprietary Specification BT Specification ------floor. If they are to be left disconnected, then STC Single-mode Cannon LLE Cannon LLE or COF 4A wind the cable into a loose coil, greater than GEC Diamond Diamond or COF 4A 100 mm diameter, avoiding any sharp bends PTL Seiko SAP-1 Seiko SAP-1 or COF 4A and tie the coil together. STC Multi-mode ITT OFP101 or Stratos SS430 or SSR430 GEC Hellerman-Deutch "Kiiklok" Before re-coupling optical connectors, the PTL PTL FC704 "Taplow" or PTL FC703 end faces of the connectors and the coupler apertures must be cleaned with an air duster. Connectors adopted as BT standard are: Multi-mode: Connector Optical Fibre no. 2A (COF2A). See figure 1 ("Stratos" Ruggedised 430 series) Cleaning aids Single-mode: Connector Optical Fibre no. 4A (COF4A}. See figure 2 The following will be available from the ("Leetec" FL4000 series) Vocabulary of Engineering Stores as general-

- 33 sector items in due course. However an initial issue of kits is to be made by TS02.1.1 in April of 1985, for use on POLS and SOS. •KIT 721A (Optical connector cleaning kit) •KIT 722A (Replenishment kit for KIT 721A) KIT 721A comprises a plastic carrying case containing an aerosol air duster, cotton buds, cleaning solvent and a selection of optical connector dust-caps. Also available as a special sector item are Microscopes No. 1A which are specially designed for the inspection of optical connectors. When using a Microscope it is important to follow the instructions given in TS02.1.1 Group Memo no. 27 (OFDLS15), and never use a Microscope on a connector carrying Laser or LED light. Note that the light is not in the visible spectrum, and therefore cannot be seen. Figure 1: Connector Optical Fibre no. 2A Figure 2: Connector Optical Fibre no. 4A Cleaning a connector comprising 2 * POF 2A plus a Coupler compnsing 2 * POF 4A plus a Coupler If the connector end face is accidentally touched or otherwise contaminated, the following cleaning process should be necessary repeat the cleaning procedure which can be dispatched to meet field performed. View the connector with a until thoroughly clean. maintenance and repair needs. Requests for Microscope, and if dirty, clean the end face assistance when faulty connectors are with the aerosol duster. If this is unsuccessful Faulty connectors discovered should be sought via your further cleaning can be performed using a Faulty connectors are found on test-cords, supervising officer from NN/TS02.1.1 head clean cotton:bud dipped in the solvent and they can be repaired at Guildford ARC; office. gently wiped across the end face of the TS02.1.1 group memo 18/83 (OFDLS 09) (01-432 9142) connector. Wipe dry with the other end of the refers. In addition a central stock of spare cotton bud, then use the aerosol duster connectors and piece-parts are held at again. View under the Microscope and if Guildford ARC together with terminating kits 34 Eleetronie Conaponent Suppl~ by Trevor Morton-Holmes MC1.5 component user's requirements. The three list of all electronic components used within Yes, I'm afraid it's another abbreviation to primary in-house BT stockists, namely BT, detailing suitable sources of supply. In remember, but 'Co-ordinated Operations for Materials Fast Response Service (FRS), the meantime each in-house stockist has the Supply of Telecoms Electronic British Telecom Research Laboratories produced their own catalogue listing the Components' (COSTEC) is rather long winded Electronic Component Distribution (BTRL components available. to say. ECD) and BMF Electrospeed Components, decide how best to meet those requirements. In-house stockists Component availability problems COSTEC is co-ordinated by Materials and Materials FRS at Bridgwater is the major in­ In these days of ever changing products and Components Centre (MCC) which is looking house BT electronic components supplier. systems, field staff must be able to obtain after the corporate interest and is concerned They stock a wide range of high quality replacement components at the right with the quality, reliability and sourcing of components for numerous systems which standard and quality as soon as they need components. As you can see in figure 1, can be ordered over the telephone and them. This principle applies to all electronic COSTEC enables direct communication despatched the same day. This ensures that components, even those 'difficult' between component users, buyers, stockists users know immediately which items are in obsolescent components, customised chips and suppliers of electronic components. stock and the quantity available. Paper and low volume items. requisitions (A 1063/A631 0), facsimile and Market intelligence telex messages are other acceptable The solution MCC is the interface between BT and the methods of ordering but obviously they do not COSTEC has been established to overcome electronics industry on component matters. It give instant information of the stock positions. your electronic component supply problems. has frequent meetings with component BTRL ECD at Martlesham handles All you have to do is tell the COSTEC manufacturers in order to gather market components for the newly developed divisional representatives the problem and intelligence and predict future technological products and systems. They accept we will help. developments and industrial trends. It attends telephone enquiries and orders by A 1063 We use the information from the ORCHID BSI committees in order to influence requisitions. The service offers fast turn­ (Off-site Repair Committee -Inland Division) specifications and standards both at national around and delivery to all parts of BT. on new products or systems to be repaired to and international levels. It also represents BT BMF Electrospeed Components at anticipate your spares requirements. at major 'component user' organisations Birmingham will supply components for However if you still have difficulty obtaining such as, STACK, EXACT and DATAOUEST. equipment that BT Factories handle. This is replacement components please contact us. Costec objectives an extension of their well established COSTEC aim to provide British Telecom with Strowger Piece Parts service. Urgent orders What is COSTEC an economical, rapid and assured supply of are accepted over the telephone without the It is a group of people who meet regularly to suitable components using modern buying need for covering requisitions. discuss the purchase and supply of and distribution techniques. electronic components for products or Corporate concern systems used within BT. Representatives How costec meets its objectives Our in-house suppliers should be used first from LCS, N NS and BTl provide the Costec intends to produce a comprehensive and foremost in preference to all external - 35 suppliers. Equipment 'whole life' costs will be Costec representatives BMF/AS1.4021-7722361 Ext:2141. dramatically increased if you buy If you have any component supply problems COSTEC has developed this supply operation components that are not of the right please inform either you local representative to meet your needs and it is flexible enough standard. BT has no quality control over or the in-house stockist: to allow for changing requirements. If you components supplied from external LCS- Mr K Jeffrey AES2.3.2 01-432 2870. have any comment on the current operations electronic component distributors. Their NNS- MrS Wood TS02.2.3 0532 433265. or suggestions for future improvements components are expensive, generally more BTl- Mr D Hensen CE2.1.3 936 2431. please contact Trevor Morton-Holmes. than twice the cost of those supplied by Materials FRS- Mr A Pagan M6.3.2.3C (01-250 6556) COSTEC stockists. And they give no 0793 484572. guarantee for the continued supply of their BTRL ECD- Mr J Hill R1.4.2 0473 643173. items. Electrospeed Components- Mr R Harper

.F"g 1 ure1 COSTEC - Co-or d mae t dO pera t"1ons or the Supply of Telecoms Electronic Components British Telecom Component Users (Design, maintenance, repair, planning and so on) .

I I • British Telecom I I ' research labs. electronic I tI component I I LCS •I distribution I (BTRL ECD) Martlesham ~---· Primary ~····· ~·····---· electronic BT component Material Dept. component suppliers fast response . user within service (FRS) ...... ~···· NNS representatives British Costec 1- Telecom Swindon/ co-ordinated by Bridgwater ---· Materials and Components Centre ---· (D&P/MSP8/MC1)

BT Factories ~····· ~····· Electrospeed ~---· BTl components ---· Birmingham Key. + Component supply .., Market intelligence• Component supply information• • • • • • • • ._ (STACK, EXACT, DATA QUEST) Information feed-back ------.- 36 International videoeonfereneing by Dave Hudson and Rod Hart 182.4.1 Services Background At the present time there are three Until recently international videoconferencing international public videoconferencing Whiteboard from the United Kingdom was transmitted services from the UK. These go to the USA camera People cameras over analogue broadcast TV circuits. This via transatlantic cable TAT? (AT&T) and via I was an expensive means of communication satellite (SBS) and to Canada via satellite and resulted in low usage of the service. (Teleglobe). All three are working on a 3 year In 1983 the situation changed with the commercial trial basis and their financial Control _..-- Document successful completion of a BT video viability is constantly being monitored with a panel ~ table development. The bandwidth used for full review at the end of that period. transmission was cut considerably by using a Similar trial services will open to European ~ Graphics new piece of equipment, called a conditional countries this year starting with West ~ camern replenishment codec, which converted the Germany. 0 0 0 0 (mounted in ceiling) analogue sound and vision signals produced The main demand at the moment is for the from videoconferencing room equipment into use of public videoconferencing rooms which ""Whiteboard a digital data stream. The Codec could send are supplied by BT and booked by customers Figure 1: Video conferencing room and receive data at 2 Mbit/s, working over on an hourly basis. There are also a few European networks, or at 1.5 Mbit/s to North private customers who own their own the range. Figure 2 shows the equipment American networks. The picture quality was videoconference rooms and lease a line to configuration. high and perfectly acceptable to users when the international gateway exchange. They Normally up to 6 people are able to using the new techniques. then book time over the international link participate in a conference from each room The codec used in the UK is based on a when needed. and they are viewed from 2 cameras. To specification originated from a project called It is expected that, as the benefits of show diagrams or documents a high COST 211 under the auspices of the EEC. videoconferencing become more widely resolution camera is mounted vertically in the Several European countries took part in the appreciated, the main demand in the future ceiling, or on a stand, pointing to a document Project, the UK being represented by BTRL. will be for private facilities. table. The Codec is manufactured by GEC in the Often a wall flip chart or a whiteboard is UK. Other EEC countries have their own Vldeoconferencing room provided and this is viewed from a camera manufacturers. Videoconferencing rooms can range from mounted on the opposite wall. Codecs have also been produced in other being a normal office, with minor A video recorder is sometimes used, to parts of the world, notably in the USA and modifications to improve the lighting and either record the meeting or to play back Japan but none of those proquced in non­ sound properties, to a fully equipped specially previously recorded tapes. When used in the European countries conform to the COST 211 built studio. transmission direction, a time base corrector standard. Figure 1 shows a physical arrangement of is used to improve the quality of sync pulses equipment for a typical room in the middle of coming from the tape. - 37 Sound and vision signals input to the Zoom/Focus Transmitted picture codec are digitised and coded into a 2 Mbit/s control monitor data stream. The reverse function is Person L------c:::J performed in the receive direction. cameras r------C=::J • Codec The Codec has two modes of operation, face to face and graphics, which are selected by a control button. Whiteboard When the whiteboard or person cameras camera are used then the face to face mode is selected. Camera 1------<~--~l Video control in 2 Mbit/s In this mode the codec makes use of the fact that in a conference there is not normally a lot of movement. An adequate picture can Zoom/Focus Codec control therefore be reproduced at the distant studio Graphics by only transmitting information about those camera l parts of the TV frame that changed since the Audio in ,...... _.., last frame. ======~ If movement is greater than that normally Audio out r------+----:--Face to expected then element sub sampling and face/Graphics field sub sampling occur to ensure that the r------1-----Control data output rate is constant. The missing information is made up by the receiving codec after addressing its likely content r-----f Video out 2 Mbit/s following examination of the received data. When the graphics camera is used to view Video recorder Time base documents then the graphics mode of the corrector codec would be selected. A high resolution image is then transmitted by dot interlace sampling, that is, scanning the picture repeatedly and sending every 19th element to Audio a frame store at the receiving codec. The control effect is to build up the picture on the screen and D- at the distant studio over several frames by echo Received picture slowly filling in the picture elements. This cancellor monitor produces twice the resolution of full bandwidth TV. The codec has 1.5 Mbit/s and 2 Mbit/s Figure 2: Video conferencing room equipment configuration interfaces and can accept 625 line PAL or 38 525 !ine NTSC standards. digital and analogue sections. up to transmit and receive only 1.4 Mbit/s of The links in the UK to the satellite earth useful data. In addition to this the codec in • Echo stations are all digital and then analogue over the UK studio is also set to add padding bits Normally studios used fo international the satellite. Modems are used at the earth to bring the data rate up to 2 Mbit/s in order videoconferencing have some form of echo stations to convert from digital to analogue, to go over the megastream link. These cancelling. Without this a speaker will find and these are mainly QPSK (Quadrature padding bits are then removed normally at that his voice will come back to him in the Phase Shift Key) modems developed by BTRL the international gateway, by a remultiplexer. form of an echo because of the transmission (R6). They connect to the satellite sub-system The Remultiplexer changes the bit rate from delay and the acoustic coupling between the at an intermediate frequency of 70 MHz. 2 Mbit/s to 1.5 Mbit/s and the corresponding loudspeaker and microphones in the studio at On the AT & T circuit the link is digital from coding from HDB3 to T1. It was developed by the distant end. the UK room to Mondial House but then is BTRL (R 16) specifically for the international analogue from Mondial to the USA. videoconferencing service (IVCS) although it Transmission The modem used for the analogue section can be used with any data stream at these A typical transmission path is shown in figure is a DIV (Data In Voice) modem made by NEC rates that conforms to CCITI Rec G732/G733 3. The UK videoconference room is of Japan. It employs VSB modulation and structures. connected by means of a megastream link, to produces a signal over the band 1188kHz to When connexions are made to foreign the international gateway at Mondial House 1532 kHz which occupies supergroups 5 and videoconferencing rooms that use codecs where the circuit appears at a patching point. 6. that are not compatible with our own a At this point the circuit can be patched to any In the USA and Canada the bit rate is 1.5 system of double encoding is adopted. This international videoconferencing circuit. Mbit/s and signals are required to be occurs at the foreign countries gateway The international circuits used are routed presented to their networks in accordance exchange where a COST 211 codec converts over cable and satellite, including small dish. with T1 coding rules. To accommodate these the signals coming from the UK back to All the circuits used contain a mixture of requirements the codecs at each end are set analogue sound and vision. These are then-

Figure 3: Typical transmission Foreign UK National national network 0 1network 1 UK Gateway I UK .. Foreign I Foreign I I Foreign (Mondial Frontier . frontier Gateway Room UK room I I I . ·. I I I I I House) I station 1.' •, I station I I I I I I 1,' '•I I I I Room Costcodec I I ~· j. I Cost codec I I equipment I I I ,'I I·· I I I I I I I I I I I I I I I I I I I I I Remux QPSK I I QPSK Foreign I Foreign I I I modem I modem codec codec I I I I I I I I I I I I I I I 39 Fast response redigitised and coded into a new form by the have occurred. serviee for other codec for transmission over that The DIV modem has a limited but countries network to the studio. adequate alarm array and the QPSK modem eonaponents­ indicates failures of the 1.5 Mbit/s, 2 Mbit/s Maintenance and carrier (70 MHz) inputs. The ISPC (International Sound Program FRS Centre) has been designated the Fault Report The future by Andrew Pagan Point (FRP) and circuit control for the IVCS. European commercial services to four Materials Department M6324 The ISPC is the initial customer contact point contries are now being established and The third issue of the FRS Catalogue was for service problems and will co-ordinate following this it is intended to start published in February and contained initial fault localisation on the UK part of the engineering trials to Japan and Australia; approximately 2,000 items for general circuit from the studio frontier stations. tests have already been performed over maintenance, repair and planning, as well as Equipped with a monitor, camera and analogue circuits to these countries. During supporting over 20 specific products. codec the ISPC can monitor circuits and the late 1980's an integrated international Orders are taken by telephone and goods actively test circuit sections on an end to end service is expected to evolve. Further despatched on the same day by first class or loop-back basis. developments are continuing. These include post. Paper requisitions (A1063/A6310), If the fault is proved to be in the UK then additional facilities, new network functions facsimile and telex messages are also responsibility for restoration or repair is and a reduction in the transmission bit rate acceptable methods of ordering but do not delegated to the relevant sub-control or used to carry good quality video. give instant access to stock positions and control stations. The future videoconferencing service will prices. If the fault lies overseas it is referred to the continue to build on the foundations of British Quantity delivery and price maintenance of distant administration. Telecom developments by exploiting existing components is becoming more important in • Diagnostics technology and network facilities. The BT's repair and maintenance activities- see The codec, remultiplexer, DIV and QPSK videoconferencing service could become one the Editorial and Les Waller's article 'Quality modems all have built-in alarms. of the most important BT services of the in the Field' in MN25. Obviously, the need for The codec has alarms which respond to 1990's. quality components will increase during the digital and video line conditions to give a (01·936 2998) coming months as new standards of quality visual warning (LEDs) and an electrical alarm are implemented. output. It continually performs an internal self The FRS is already providing the quality of check which gives an alarm condition when a components required by its customers. Each fault is detected and an LED lights on the product stocked is BT approved, BS9000 printed circuit board that has failed. (CECC) or a commercial item specified by a The remultiplexer has a self test key which, manufacturers data sheet. In the case of when thrown, causes a comprehensive test semiconductor devices only manufacturers cycle and indicates any internal failures that recommended in BT Spec D5002 are used. 40 PCA25 Measurements

The handling and storage of components atRSC's at our depot in Bridgwater are to the standards set by the BT Materials and by Tony Richardson LNS3.1.4 • Operation in two independent cyclic modes Component Centre (MCC), in particular the The quality of service at direct reporting (one only on 33A} and one manual mode, handling of static sensitive devices. repair service controls (RSCs) for '151' with independent storage facilities. We are continually introducing new items calls, and fault report calls from auto· • Storing and presenting results of both cyclic and products to our range. If you are buying manual centres (AMCs) is expressed in modes corresponding to user defined four large numbers of components outside BT or terms of 'percentage of calls answered in or five week month with automatic print-out are having problems obtaining components, 25 seconds or less'- and is commonly at the end of the period to an optional we may be able to stock the items in FRS. referred to as 'PCA25'. printer. If you would like to discuss new items or • Displaying results on a 16 character alpha­ get a catalogue and further details of the The Monitoring Unit 33A which replaced the numeric LCD compared to six numeric service, please ring Andrew Pagan on mechanical type PCA Equipment MSW 23099 characters on MU33A. (0793} 484572. and described in Maintenance News 23 • Display of average time to answer a fixed (Autumn 1983) has proved very successful in number of calls. Ken Hooper and Mike Phipps of the the field, and has been installed in over 180 • By means of a remote display in the RSC, Fast Response Service seen issuing components RSCs. connected to the main unit, display a single from the depot at Bridgwater The development of this unit however, was character derived from the PCA calculation an interim step towards a more for the last twenty calls. comprehensive measuring equipment, and • Print out of stored information by means of the next stage in development will be the a V24 interface, with automatic print out on introduction of the Monitoring Unit 338 with request at five minute intervals. increased facilities. • Results saved under power fail conditions. This new unit is now on test and, subject to • Indication of the average time to answer satisfactory results, it is hoped to place a the last twenty calls. production order within the next few weeks. • An improved user defined security code to The basic parameters for measuring PCA prevent unauthorised use. are of course similar to those on the Monitoring Unit 33A. Extra facilities available Cost on the MU338 are It is anticipated that the price of the MU33B • Monitoring up to 30 incoming 151 or AMC will be less than £900. The cost of a remote circuits to detect calling and answering display unit, VDU and printer will be extra. conditions (1 0 only on the 33A} • Registering conversation time in six second Installation units. Installation and dimensions will be similar to ... 41 the MU33A, and the plug-in test unit for the AT/ATW.626700 will be available shortly for MU33A which is available on a per the MU.33B and the Item Code number will Letters Region/District basis (and is already held by be 39-1236. The Specification for the Display some Regions) will be compatible with the Unit 12A will be AT/ATW626710, and the Item Prompted by Roger Sutton's article on new unit. Code number will be 37-5037. The unit is designed to be desk mounted Requisitions should be forwarded to this 'Noise' Don Wiltshire of Merlin Operations writes- and produced in a colour scheme which Group for the initial supply of this item. In the investigations into noise problems and blends with the 'Crown Supplies' range of In addition to new RSC installations, it is furniture. The unit is angled at 30 degrees for suggested that the MU33B could be the plan of action described in the article, it is surprising to find no reference to any acceptable viewing and ease of operation, substituted at RSCs where more than one investigation into the integrity of wire and in addition the alpha-numeric display has 33A is being used to monitor over ten a separate adjustment to improve readability. incoming circuits, or where 24 hour service is termination systems, particularly those used in operation. in the external network, the performance of Ordering procedure (01-432 2876) which is crucial to the overall performance The Specification and Diagram Notes and reliability of the network. Studies prior to the introduction of insulation displacement connections (I DC) for use in customers' premises, showed that existing systems were deficient from a performance and useage point of view. Our studies revealed that due to lack of proper quality controls the use of wire wrapping was ill advised. The worst example of a termination technique that came to light was the CWI 1A, a crimp termination used extensively in the network for jointing cables. Usage of this device at that time being in excess of 100 million per annum. When subjected to initial termination resistance and accelerated aging tests1 the performance of these devices falls woefully short of any acceptable standard. An article by H E Hines in British Telecoms Eng Vol 1, part 2 July 1982, shows clearly that the measured performances of all the

1 (See Dons article in British Telecommunication Engineering, Vol 1, part 1, April 1982) 42 IDC's he tested were within the required test it will be with us for a very long time. technology. They usually do not have access parameters and that none of the CWI 1A's In the context of replacement it is to performance specifications and have failed could meet these standards of performance. disappointing that a version of the 'trim lock' to identify and resolve the problems with A description of the tests used to evaluate type of connector which is suitable for a no cable terminations that undoubtedly exist. termination is contained in an article by Dr B break changeover is not used in preference Like many of BTs problems, this stems from a Wiltshire in British Telecoms Engineering, Vol to the series 8 connector. No doubt the cries failure to manage the technical aspects of 1, part 3, Oct 1982. The evidence relating to of 'it's too expensive' have won the day our work. the poor performance of the CWI 1A has again. There would also appear to be serious been available for many years. It is not used A vital clause in Specification D 2920, calls deficiencies in our training schemes. How on plastic insulated cables by other for production tests to be carried out on often are visiting speakers, from research telephone administrations. They also, wisely, completed terminations in order to monitor and development divisions, expert in a do not use aluminium conductor cable which the performance of the termination device, particular field, asked to give a talk on is notoriously difficult to terminate reliably. tools and operators. Without this control, a technical matters to students on engineering An article written by Mr D V Thorpe (British wireman with a batch of faulty devices, using courses? Our experts are frequently invited to Telecom Eng, Vol 2, part 4, Jan 1984) a worn or damaged tool, who had been address international conferences, why so describing the testing of customer lines inadequately trained or had a weak wrist seldom within BT? suggests that faults due to additional series could make thousands of unreliable Failure to address these problems in the resistance in the line may be due to corroded terminations without detection. past is currently costing the business very joints. The failure of BT to use the more large sums of money, much of this Increased resistance at joints, often an expensive full cycle tools, which make it expenditure could have been avoided. indication of corrosion, will almost certainly impossible to release a crimp until the The November issue of Management make the termination act as an effective correct pressure has been applied is also a News shows a picture of Mr John Tippler, noise generator. It is also likely to be false economy. Head of Engineering, LCS, having a close intermittent and subject to traffic vibration. Investigations into BT's external plant have look at the external network. There is to be a The use of CWI 1A's in street cabinets with revealed that a significant proportion of major effort to reduce the fault rates. I would the likelihood of their being disturbed by field external staff are creating work for another venture to suggest that the causes of many staff also seems to be bad practice. It is significant proportion. If you use a CWI 1A of the problems are known, the solutions are inevitable that any poor termination will be this is very probably true. We are paying a available, their implementation is long disturbed, creating noise. heavy price in BT for some of the decisions overdue. I am aware that Series 8 connectors, taken in the past with cost being the which do meet an acceptable termination dominating factor, a spell of reliability being lan Dufour LCS Network Quality standard, are now being introduced, although top of the list would not go amiss. Manager comments- the rumour that it is to be cost reduced is Few of my colleagues working in telephone worrying. Some Areas are still using the CWI areas on external activities appear to have a Mr Wiltshire's very interesting letter has 1A and without a positive replacement policy good knowledge of fundamental termination identified a number of problems that have - 43 been experienced with termination commenced in 19S3. To date something like adjustment. However, a cartridge tool, which systems- particularly those of the Connector 150 millions of the standard connector (CWI may be more efficient in some jointing Wire Insulated No. 1A (CWI 1A), it has been SA) have been used in the field. In addition a situations, is under field evaluation. recognised for some time that it does not 3 wire connector (CWI SB) and a connector As regards quality control, checklist quality perform well in accelerated aging tests and with a teeing facility, CWI SC, which can be procedures have been successfully used for there is some evidence of failures in the used for no break changeovers, are also external jointing work since 19S3. Checklists field. available. to cover other external activities are also The major factors affecting the long term The implementation of the CWI SA has not, being developed, including a computerised stability of the CWI 1A are contact however, been without problems. Jointers information system to replace the existing degradation, caused by expansion of have experienced difficulties with wire paper orientated system. In addition a THO insulation trapped within the crimped insertion and with the initial SA crimping tool. Network Quality Team has been set up to connector, and the need for the crimping tool A new crimping tool has been provided and oversea quality matters and liaise with Area to remain in calibration to give the correct the evidence is now that these problems are Quality Managers. degree of closure. being overcome as training and experience I would like to thank Mr Wiltshire for the In view of the problems with the CWI 1A, it take effect. The right training is of course vital interest he has shown and for highlighting was obvious that a connector with an and Mr Wiltshire's point on more experts some of the areas which affect quality in the improved performance was required. giving talks on training courses is being Network. It is vital that we create a natural It was considered that an insulation pursued with training branch. acceptance of quality so that it is taken for displacement connector (I DC) would meet It is undoubtedly true that a number of granted by staff at all levels. A 'hearts and this need because faults are self inflicted, particularly those in minds' exercise was started at a conference -It is less sensitive to the thickness and type cabinets. The problem can be reduced by of GMs and Senior Managers in November of insulation. restricting access to cabinets: however, 19S3 but a great deal more remains to be -It can be more readily sealed to prevent indications are that a cabinet terminated with done to achieve an automatic acceptance of corrosion. CWI SAs will have a very low fault rate. the need for quality. -A simple crimping tool can be used. Modular IDC's in cabinets are also under Laboratory testing and evaluation confirmed evaluation. that, compared with the CWI 1A, an IDC gave There is no substance in the rumours that a more reliable electrical performance, was the CWI SA will be cost reduced. Indeed, more resistant to corrosion, covered a wider manufacturers have been made aware of the variety of wire insulation and was easier to desirability of a future connector with easier use. wire entry, and increased depth of wire The result of this work was the insertion and a test facility. development, in co-operation with several Similarly the new crimping tool was not manufacturers, of a new I DC, designated the chosen on the basis of cost but primarily CWI S, the implementation of which because it is simple to use and requires no 44