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Fig. 13The M5/BYB bay equipped with three transmultiplexersfor 60 channelsBMBuilding moduleFor traffic towards the TDM side unitscan be provided which permit the connectionof eight 64 kbit's data channels,in place of eight of the speech channels.The data channels, which give an extremelylarge data transmission capacity,can for example be used to transmitdata bit streams from a digital data multiplexerSuch a unit can be connectedin during operation without disturbingother traffic. The available bits in timeslotTO are also accessible.The transmultiplexer can be partiallyequipped to suit lower capacity requirements,resulting in lower costs.For AXE 10 it is possible to connect avariant of the transmultiplexer direct tothe digital group selector In this casethe ETC (Exchange Terminal Circuit) isnot required in AXE 10, and the transmultiplexercan be integrated into thestructure of the system, which is advantageousfrom the point of view of handlingand maintenance.Operation and maintenanceEricssons transmultiplexers do not requireany preventive maintenance. Thesystem parts are designed so that veryhigh stability is obtained throughoutthelife of the equipment.The equipment contains alarm monitoringand alarm transmission in accordancewith CCITT recommendations.All alarm information is available in aspecial alarm unit. This unit also transferssome alarms between the FDM andTDM sides. All transmultiplexer alarmscan be allocated to the urgent or nonurgentcategory by means of straps inthe alarm unit.Reminder indication can be initiated bymeans of a push-button. When an alarmoccurs, a light emitting diode on thefront of the unit lights. Several units inthe subsystems are also equipped withlight emitting diodes, which simplifyfault tracing The alarm unit also containsservice alarm outputs, whichprovide alarm information for the wholeequipment as well as individual subsystemsat carefully chosen levels. Thealarm outputs can be connected toalarm equipment of the traditional typeor to Ericssons computer-controlledalarm system, ZAN101.Fig. 12ZAJ 2x30/60, transmultiplexer for 60 channelsDetailed measurements can be carriedout from various test points. The FDMpart contains short-circuit proof testpoints at important system points andalso access points for connection to thespeech frequency and signalling interfaces.The PCM part contains short-circuitproof test points for, for example,the transmitted and received bit streamand the transmitter and receiver timing.On the FDM receive side manual levelregulation can be carried out individuallyfor each channel as well as for eachbasic group. This means that the residuallevel deviations, such as thosecaused by a complex network configuration,can be compensated. Incominggroup or supergroup pilot frequenciescan be monitored for interruptions by apilot receiver, which can be included inthe equipment. The frequency of thesend clocks can be adjusted. IncomingTDM bit streams are supervised for lossof timing and bit error rate. All test andmeasuring points are readily accessibleat the front of the equipment.
191Fig. 15Control unit with microprocessorThe basic principle of the transmultiplexerasregards alarms is that it shouldbehave as a PCM multiplexer towardsthe TDM side and as a carrier systemtowards the FDM side. There are certainextra features, however, such as thetransmission of the AIS (Alarm IndicationSignal)Fault-clearing maintenance consists ofchanging faulty printed board assemblies,and a suitably dimensioned stockof spare parts must therefore be available.The conventional structure ofEricssons transmultiplexers meansthat many of the boards are also used inother Ericsson multiplex equipments,so the stock of spares can be shared,with a consequent reduction in maintenancecosts.System structureThe description above applies in the relevantparts for all Ericsson transmultiplexers.The mechanical constructionand functional design of three differentequipments are described separatelybelow.ZAJ 2x30/60The transmultiplexer for 60 channels.ZAJ2x30/60, fig. 12, converts two2048kbit/s PCM streams to a standardizedbasic supergroup in the frequencyband 312-552 kHz and vice versaThe equipment is built up using Ericsson'sBYB construction practice. Allequipment for the transmultiplexer ismounted in a pre-wired triple magazinehaving a width of 12 building modules(488 mm) and a height of 18 buildingmodules (732mm). The magazine is anindependent unit which also containstwo d.c./d.c. converters. The magazinecan be mounted in M5/BYB bays 2 , inBYB rows or in a BYB cabinets. All cablingis accessible from the front. An M5/BYB bay can be equipped with threetransmultiplexers, fig. 13.As far as possible the transmultiplexerhas been built up of the same parts asEricsson's other multiplexer systems.The functional structure is shown infig 14. The TDM part contains two identicalPCM units. These subsystems containwell-tried system componentswhich also form part of AXE 10 as well asseparate PCM equipments 3 . The FDMpart contains units from Ericsson's FDMsystems 4 . The continuous technical developmentalso affects the FDM field.For example, hybrid type thick film circuitshave been replaced by monolithiccircuits in the signalling circuits, whichmeans that it has been possible to reducethe number of integrated circuitsby a third on the send side and by half onthe receive side. The necessary carrierand signalling frequencies are generatedinternally with the aid of phaselocked oscillators, which are controlledby an incoming basic frequence of 12 or124kHz The group pilot frequencies,84.08 or 104.08 kHz, can either be generatedinternally or obtained from an externalsource. The supergroup pilot frequency,411.92 or 547.92 kHz, is obtainedfrom an external source. FDM terminalsnormally contain central fre-Fig. 14Block diagram of the transmultiplexerZAJ 2x30/60RflRacif nrnnn inlprf.irr
Page 1: ERICSSONREVIEW41982REMOTE AXE 10 SU
Page 4 and 5: ;2Remote AXE 10 Subscriber Switchin
Page 6 and 7: Fig. 3The container is brought out
Page 8 and 9: An Optical Fibre Line Systemfor 34
Page 10 and 11: Fig. 3Repeater spacings and hardwar
Page 12 and 13: 182The primary alarms are those rec
Page 14 and 15: 184Technical dataDigital interface
Page 16 and 17: Fig. 2, leftThe transmultiplexer as
Page 18 and 19: 188Fig. 9Synchronization of the tra
Page 22 and 23: Fig. 17ZAJ 5x24/2x60, transmultiple
Page 24 and 25: ERITEX10 for Teletex and WordProces
Page 26 and 27: Fig. 5The central processing unit i
Page 28 and 29: 198Fig. 8The floppy disc unit with
Page 30: 200- finding space for a document o
Page 33 and 34: Local Area Radio System-LARSHans Li
Page 35 and 36: Fig. 5One of the thick film hybrids
Page 37 and 38: 207Technical data for LARSSelective
Page 39 and 40: 209BERTH EKLUNDHDAVID RAPPDepartmen
Page 41 and 42: 211over, the type of traffic handle
Page 43 and 44: 213Models of CPA comparison between
Page 45 and 46: ETable 2The table shows the differe
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