ST2657

A.T. Exchange/EPABX Training System ST2657 Operating ManualVer 1.1 An ISO 9001 : 2000 company 94-101, Electronic Complex Pardesipura,Indore- 452010, India Tel : 91-731- 2570301/02, 4211100 Fax: 91- 731- 2555643 email : [email protected] Website : www.scientech.bz Toll free : 1800-103-5050 ST2657 Scientech Technologies Pvt. Ltd.2ST2657 Scientech Technologies Pvt. Ltd.3A.T. Exchnge/EPABX Training System ST2657 Table of Contents 1.Introduction5 2.Features5 3.Technical Specification6 4. Safety Rules7 5.Technology History8 6.Switching Technology9 7.Getting Started13 8.Manual Switching Theory14 9.Experiments Experiment 117 Study of working of a Manual Switch Board (switching) 10.Introduction to EPABX units.18 Power Supply Unit18 Trunk Unit19 Experiment 220 To analyze & measure the Ring Detection Phenomena Experiment 321 To analyze & measure the Trunk Relay Switching 11.Extension Unit21 Experiment 423 Study of Switching Mechanism of Relay Experiment 524 To analyze & measure the Off Hook Detection Experiment 625 To analyze the working of the flash and its use Experiment 726 Study & analyze the Amplified Receiver Signal Experiment 827 Study of Switching Mechanism of Relay 12.Control Unit/Signal processor unit27 Experiment 929 To analyze and measure the Ring enable Signal ST2657 Scientech Technologies Pvt. Ltd.413.Decoder Unit29 14.DTMF Unit30 Experiment 1031 To analyze that the DTMF receivers are limited to number of dial tone extensions. (Limitation of space division switching)24 Experiment 1132 To analyze that dialing of DTMF digits sends out two frequencies. 15.Clock Generation Unit32 16.Tone Generation Unit33 Experiment 1234 To analyze the role & measure the frequency for Ring Generation Experiment 1335 To Analyze & measure that Ring Back Tone is addition of Dial & Busy Tone Experiment 1436 To measure the frequencies of Dial Tone & Busy Tone Experiment 1537 To observe the amplified Dial Tone 17.Music Circuit37 Experiment 1638 To Analyze the Music Tone 18.Switching Matrix38 19.Ringer Unit43 Experiment 1745 To measure the high negative voltage & to analyze it is generatedall the time35 Experiment 1846 To measure the frequency and its role Experiment 1947 To measure the ringing signal 20.CPU47 21.Memory47 22.Software Experiments48 23.Test points56 24.Glossary57 25.FAQ58 26.Warranty59 27.List of Accessories59 ST2657 Scientech Technologies Pvt. Ltd.5Introduction ScientechsST2657isidealforthestudyofTelephoneExchange/EPABX.It providesthestudyofbasicfundamentalsinauniqueway.Ithasbeendesignedto meettherequirementsoftechnicalacademics.Theanalysisofvariousdetection phenomena such as on hook/Off hook, Ring detection etc. The generation of various signaling tones i.e. ring, dial, busy & ring back tone is well explained. The manualswitching, basic of exchange technology & also the automatic switching is well performed using the trainer. The trainer is of 204 configurations that is 2 direct lines&4extensions.Thetraineronboardconsistsofonedirectlinecircuit,one extension line (with direct line ) and one more extension line(without direct line) The softwareexplainsabouttrafficanalysisunitsandtheworkingpresentationofan EPABX system. Features Easy Understanding of Various Units Use of Functional Blocks than Traditional Circuitry Study of various Detection Phenomena Detailed Circuit Study LED Visualizations Study of Switching Phenomena Study of Traffic Units Switched Faults CD containing Traffic Analysis Calculator & Working Presentation ST2657 Scientech Technologies Pvt. Ltd.6Technical Specifications Number of Inputs:2 Trunk / Direct Lines Number of Extension :4 Lines Technology : Cross Point Space Division (Microprocessor based)Standard Features:Tones such as Dial, Busy, Ring Etc Dialing - DTMF and Pulse (Ratio 10pps) Program Memory:64 kb EEPROM Loop Resistance:Extension -600 Ohms, Co-line- 1200 ohms Cross Talk Attenuation : >70 dBm Test Points :More than 25 Nos Power Supply:230 V 10%, 50 Hz Switched Faults:8 in numbers Test Points:38 in numbersFeatures that can be set:Line Hunting, Direct Accessto trunk line, Redial, LineStatusIndication,Automaticcallback,Do NotDisturb,CallTransfer,CallPickUp,Direct AccessTrunkCallForwarding,Callparking, Conference,HotlineSystem,ExtensionPrivacy, Call Transfer, Barge in Weight :2 Kgs. Dimension :(L) 435 mm (W) 260 mm (H) 95 mm Fuse:2 A Power:230V AC 10% 50 Hz ST2657 Scientech Technologies Pvt. Ltd.7Safety Rules The trainer has been tested for ruggedness. But certain safety rules to be followed. 1.All extensions should be on Hook when powering on the trainer. 2.Avoid leaving the trainer On for a long time. 3.Avoid Ringing in manual mode for a long time or after extension is off hook. ST2657 Scientech Technologies Pvt. Ltd.8Technology History In the 1876's Alexander Graham Bellinvented the telephone; a wired system for two wayvoicecommunicationbetweenremotelocations.Youspokeintoaunitatone location and your voice was heard at the other location, immediately this system was somewhat limited in that .It only allowed communication with one fixed location, so it was an obvious advance to have lines going to other locations. Initially, this is what happened-each telephone had lines going to many other telephones, which meant a lot ofwiresandtherewerepracticallimitationsastothenumberofphonesonecould connect to. Soon,theideaofcentralswitchingthatsManualSwitchingwasdeveloped.Each telephoneconnectedtoacentralhub(theexchange)andfromthere,theoperator wouldconnectyourcalltoanothersubscriber.Thusswitchboardsweredeveloped where upon liftingyour receiver, an operator was alerted and you would tell her who you wished to speak. Apart from other limitations it was very labour intensive and as the popularity of the telephone grew, the number of operators employed by the Office grew;largeswitchingcentres(exchanges)couldhavemanytensofoperators,each with their own switchboard. In the early days, each telephone user was known as the 'subscriber' and that term is still used today. The Invention of Automatic Switching : Almon B. Strowger was an undertaker in Kansas City, USA. The story goes that there was a competing undertaker locally whose wife was an operator at the local (manual) telephoneexchange.WheneveracalleraskedtobeputthroughtoStrowger,calls weredeliberatelyputthroughtohiscompetitor.ThisobviouslyfrustratedStrowger greatly and he set about devising a system for doing away with the human part of the equation. Strowgerdevelopedasystemofautomaticswitchingusinganelectromechanical switch.Withthehelpofhisnephew(WalterS.Strowger)heproducedaworking modelin1888(USPatentNo.44791810/6/1891).Inthisselector,amovingwiper (withcontactsontheend)moveduptoandaroundabankofmanyothercontacts, making a connection with any one of them. Diagram of a simple Selector Figure 1 ST2657 Scientech Technologies Pvt. Ltd.9Strowger formed his company 'Strowger Automatic Telephone Exchange' in October 1891.Thefirstautomaticexchangeappearedin1892inLaPorteIndiana.AlmonB. Strowger died in 1902.Though it improved upon the performance of a manual exchange, it still had a number ofdisadvantages,Suchaslargenumberofmechanicalparts,limitedavailability, bulky in size etc. ThentherewerechronologicaldevelopmentsinthefieldsuchasAnalogswitching, Digital switching, Space division switching, Time division switching & the evolution is still on with the IP PBX. Switching Technology Matrix : Abasicswitchingnetworkorswitchismadebyarrangingcomponentsinrowsand columnsintheformofamatrix.Aconnectionissetupbetweenaverticalaccess point(columns)andahorizontalaccesspoint(row)byclosingthecrosspointatthe intersectionoftherowandcolumn,correspondingtotheaccesspoints.Thebasic switchofinletsareequaltothenumberofoutlets,itiscalledasquarematrix.The matrix and its symbol are shown in figure 2. (b)Symbolic Representation of 4 4 matrix Figure 2 ST2657 Scientech Technologies Pvt. Ltd.10Cross point : Acrosspointisaminiaturizedswitch,usedtoconnectvariouslinksofthespeech path. It has two stable states viz, closed (conducting) and open (blocking). In the open state,theimpedanceofthecrosspointmustbeashighaspossible,overtheentire range of the frequencies being switched. In the closed state, the impedance should be as low as possible. Appropriate acceptance range of values for the impedances, are Closed : 0.1-200 Ohms Open : 10-25 M ohms Switching networks may use different types of switches. Various types of cross points havebeenevolved,keepinginpacewiththeotherdevelopmentsinSPCexchange systems. The prime continuing priorityis to reduce its size, operating time, and cost. Therearetwotechnologicalcategoriesofcrosspoints,viz,electromechanical,i.e.a metallicswitch,andelectronicdevice.Theyarefurthersub-divided,asshownin Figure 3. Figure 3 Electronic Cross point : Electroniccrosspointofferconsiderableadvantageousofreducedsize,weight,and power consumption, compared to their electromechanical counterpart. However, they sufferfromhighOn-resistanceandlowpowerhandlingcapacity,comparedto metallicandMOScrosspointsare0.5ohms,severalohms,andaroundahundred ohms, respectively. Due to theselimitations, theyhaveso far beenused limitedly, in Analogue switching. ST2657 Scientech Technologies Pvt. Ltd.11Space Division Switching :TheST2657A.T.Exchange/trainingsystemworksonspacedivisionordomain switching. The spacedivision switching has its ownadvantages over other switching domainssuchasmorebandwidth,simplecircuits&easyvoicehandling.Inspace division, each subscriber or extension has it own dedicated path in the exchange. The exchange uses one full physical path& a dedicated cross pointfor one call this may result in blocking. As the number of extension increases it directly affects the number of crosspoints & circuitry. Erlang : 1.Erlangisaunitoftrafficmeasurementandrepresentsthecontinuoususeofa line for one hour.2.One Erlang represents the amount of traffic intensity carried by a channel that is completely occupied. 3.Onehour of telephone traffic in an hour oftime. For example, if circuit carries 120 minutes of traffic in an hour, that's two Erlang. A.K.ErlangtheDanishmathematicianwasthefirstpersontostudytheproblemof telephone networks. In 1917 by studying a village telephone exchange he worked out aformula,nowknownasErlangsformula,tocalculatethefractionofcallers attempting to call someone outside thevillage that must wait because all of thelines areinuse.AlthoughErlangsmodelisasimpleone,themathematicsunderlying today's complex telephone networks is still based on his work. Erlang = Number of calls Average call durationOne hour (60 min or 3600 sec) Suppose a systemhandles 408 calls of 2.5 minutes in duration duringbusiest 1hour So,Erlang (BHT) =408 2.560 (min) Erlang = 17 There are two types of trunked systems which are commonly used 1.The first type offers no queuing for call requests. This type of trunking is called Blocked calls cleared or Lost call cleared. The probability that a call is blocked is determined by the Erlang B formula. 2.The second type of trunked system isone in which a queue is provided to hold callswhichareblocked.ThistypeoftrunkingiscalledBlockedcallsdelayed. The likelihood of a call not having immediate access to a channel is determined by the Erlang C formula.ST2657 Scientech Technologies Pvt. Ltd.12Erlang B Formula : The Erlang B model is an established traffic model for predicting Telecommunication performance. This model makes assumptions about the nature of telephone traffic and may prove inaccurate under special circumstances. It is widely used to determine the number of trunks required to handle a known calling load during one hour period. It is also used to determine the probability thata call is blocked& gives the GOS(Grade of Service) for a trunked system. The formula assumes that if callers get busy signals, they go away forever & no retries where as the fact is some callers retry. Disadvantage : It under estimates the trunks required. The Erlang B formula is GoS [blocking] =! n / An) ! C / A (CC n = 0 Where, C = number of trunked channelA = Total offered traffic Erlang C : This formula also predicts the waiting time (delay) based on three things No. of lines, No.ofpeoplewaitingtobeserved&theaverageamountofittakestoserveeach person. It can also predict the resources required to keep waiting time with in targeted limits. Disadvantage : It can over estimate the resources required Traffic Analysis Definitions : 1.Busy hour : Thebusyhourofanexchangeisachosen60minuteintervalinwhichthe telephone traffic is the highest. The busy hour varies from exchange to exchange depending on its location, and the community interest of its subscriber. 2.Busy hour traffic : Thisisanamountofcalltraffichandledbyagroupofphonelinesduringthe busiesthour ofthebusiestdayforyoursystem.Busyhourtrafficisdefinedin units of Erlangs. 3.Holding time : Average duration of a typical call. Denoted by H (In seconds) 4.Grade of service (GOS) : TheGradeofservice(GOS)isameasureoftheabilityofausertoaccessa trunked system during the busiest hour. It is a measure of congestion which is specified as the probability of a call being blocked, ortheprobabilityofacallbeingdelayed beyondacertainamountof time. The grade ofservice of .002 means 2 calls per 1000 or 1 in 500 has been lost. ST2657 Scientech Technologies Pvt. Ltd.13Getting Started The ST2657 is of 204 configuration, 2 direct lines & 4 extension lines.Monitoring Tones : It is necessary to get familiar with the various "tones" of your EPABX System. 1.ExchangeDialTone:Thedialtoneisacontinuoussoundandsoundslike uooncontinuouslywithnosilenceperiodbutgetsinterruptedinterval.Itlasts for 8 seconds during which the exchange waits for dialing to be initiated. If no dialingtakesplaceduringthisperiodtheEPABXtimes theuseroutand starts issuing a busy tone. 2.DOT,P&T,andCentralExchangeDialTone:Onaccessingadirectline, you will obtain the normal P & T dial tone. 3.Busy Tone : The busy tone is a discontinuous sound (Du-Du) with On & Off periods.Therearekinds of busytoneswithdifferencesinOn&Offperiod or pitch. This tone indicates that the system is too busy to accept any operation. This tone converts to a dial tone as soon as the system isfree enough to accept your dialing. The type of busy tone (which is the slow one) is encountered when called subscriber number is busy. 4.Ring Back Tone : This sound is continuous with silence period. When you dial extensions, you will hear this ring-back tone till the extension answers. 5.RingingTone:Therearetwotypesofringsthatcanbeheardfromthe telephone instrument connected to the System. a.When your instrument is called by another internal instrument the ring will be a continuous one with a one second On and 3 seconds Off period. b.A ring from a Co. In. (Trunk) Line will ring like a normal telephone. 6.In-ComingCallQueuingTone:Thistonewillbeheardwhenacalleris waiting for your extension to get free. It is similar to the feature mode tone and willbeheardrepeatedlywithalongpause.Thistonewillonlybeheardonly when there is a Co. In. (Trunk) incoming call. Intrusion Tone: (Barge in Tone) : This is-a fast beep. 7.HookFlash(HF):ThefeaturesofyourEPABXrequiretheuseofaHook Flash (HF). This is performed by tapping the hook switch ofyour extension for a period less than 0.5 second. Care should be taken not to press the hook switch for more than 0.5 seconds when a HF is desired. If the exchange hook switch is pressed for longer than 0.5 seconds it will register a "hang up" or "reset". Telephone instruments have a built in electronic flash key. It is advisable to use the flash key instead of the hook switch in order to register a "hook flash". ST2657 Scientech Technologies Pvt. Ltd.14Features/Operations : 1.Access to Trunk Line (0) : (Line hunting) Extensionsareprogrammedtohaveaccesstoalltrunklinesbydialing27for trunk0,28fortrunk1&dialingof0willaccessesthetrunkbylinehunting. Extensions can also be denied this access. 2.Extension to Extension Call (Extension) Whenoneextensionuserwishestotalktoanotherextension,theuserhasto proceed as follows :Lift hand set & hear dial tone. Dial Extension Number Wait for the internal ring tone. Speak when called party answers. 3.Redial :Anyextensionusercanrepeatedlydialthelastnumber(whetherinternalor external)without pressingallthenumbersagain.Forthisfollowtheprocedure below : Disconnect previous call. Lift hand set and hear dial tone.Dial * asterisk key. The last dialed number will be redialed automatically Manual Switching Theory A simple Central Battery system operated by a human being is shown in Figure 4. The systemconsistsofoneswitchboardmannedbyoperator.Thesubscriberlinesare terminatedonjacksmountedontheswitchboard.Thereisonejackforevery subscriber line. Associated with each jack is a light indicator to draw the attention of theoperator.Whenasubscriberliftsthehandset,theoff-hookswitchisclosed, causing a current to flow through the hand set and the lamp relay coil. The lamp relay operatesandtheindicatorcorrespondingtothesubscriberlightsup.Theoperator establishescontactwiththesubscriberbyconnectingtheheadsettothesubscriber linevia theheadsetkeyand a plug-ended cord pair. A plug-ended cord pair has two cordsthatareconnectedinternallyandterminatedwithaplugeachattheexternal ends. The plugs mate with thejacks. To establish contact, acord is pluggedinto the subscriber jack and the key corresponding to the chosen cord is thrown in position to connecttheheadset.Onbeingtoldthenumberrequiredbythesubscriber,the operatorverifieswhetherthecalledpartyisfree,andifso,sendsouttheringing current to the called subscriber using a plug-ended cord pair.ST2657 Scientech Technologies Pvt. Ltd.15 Figure 4 The ringing, circuit at the subscriber end is usually a bell shown as B in Figure 4, with acapacitorC,inseries.Theyremainconnectedtothecircuitalways.Thecapacitor allows the alternating ringing currentfrom the exchange to pass through thebell but preventstheloopdirectcurrent.Ifthecalledpartyisbusy,thecallingsubscriberis told about the same. When the called party answers, his indicator lamp lights up.The operator then establishes a connection between the calling and the called party by plugging in the cord pair to the called party jack. The supervisory lamps used to glow duringconversationandwouldbeextinguishedwhenthesubscribersreplacedtheir handsets.Thistypeofclearingsignalusedtobecallednegative.Thereisanother methodinwhichduringconversationboththelampsareoff.Attheendof conversationwhenboththesubscribersreplacetheirhandsets,boththelampsglow indicating to the operator that the cord circuit is free. The operator then withdraws the plugsfromthejacks,andmayusethecordcircuitforestablishinganother connection.'Theglowingofthesupervisorylampwhenasubscriberreplaceshis handsetiscalledtheclearingsignal,andapositiveclearingsignal..Thisiscalled positive, as the clearing is indicated by a positive appeal to the sense of the operator. In this particular case the positive appeal is to the eye and the object is glowing lamp. A positive signal maintains a persistent effect on the nerve of the operator, so that the operator is very unlikely to forget to unplug the cord circuit. Inamanualswitchingsystem,theoperatorhasfullcontrolofaconnection.He enablesthesignalingsystems,performsswitchingandreleasesaconnectionaftera conversation. ST2657 Scientech Technologies Pvt. Ltd.16Using ST2657 in manual mode : Procedure for Setup : Step 1 - Connect the socket of the AC Adapter. Step 2 - Connect the telephone instruments to all the extensions 30 -33.Step 3 - Extension 33 is being used to act as an operator. Step 4 - Operate switch fault 2 to 7 number to On position. Step 5- Press the switch for manual mode. Step6-Connecttheblackcordprovidedtotheoperatorjack&keeptheotherend open. Step 7- Connect the red cord provided to the ring jack & keep the other end open. ST2657 Scientech Technologies Pvt. Ltd.17Experiment 1 Objective :Study of working of a manual switch board (switching)Procedure : Step 1Liftthehandsetofext30, TheLED(lamp)correspondingtotheextension will glow. Which is an indication to the operator that the subscriber has gone off hook. Step 2Connect the one end of the black cord to extension 30 jack& the otherend is already connected to operator jack.Step 3NowDCloopbetweenthesubscriber&theoperator(Liftthehandset)is formed.Ext30subscribercanasktheoperatortoconnecttodesired extensions. For example let us take, the subscriber wishes to speak to extension 32.Step 4Theoperatorhastoextendtheringsignal(current)tothecalledextension, thisisdonebyinsertingtheotherendoftheringcord(red)intothe extension32jack.Thetelephoneinstrumentattheextension32starts ringing. Step 5Onhearingtheringtheextension32goesoffhook,soliftthehandsetat extension 32 & thecorrespondingLED (Lamp) glows on the switch board. Thisisanindicationtotheoperator.Nowstopextendingthering,remove the cord (red) from the extension 32 jack. Step 6Now remove the black cord from the operator jack & connect it to extension 32jacks(Checkextension30&32areinterconnectedwithblackcord). Now the callis formed between 30& 32.The operator is free to attend the nextcall.TheLEDs(lamp)glowsaslongasconversationisOn.The LEDs goes offasthe extensiongoes Onhook .The operator removes the cord. ST2657 Scientech Technologies Pvt. Ltd.18Introduction to Epabx Units A telephone exchange (EPABX) consists of various units. They are. 1.Power Supply 2.TrunkUnit 3.Extension Unit 4.Control Unit 5.Decoder Unit 6.DTMF Unit 7.Clock Generation Unit 8.Tone Generation Unit 9.Ringer Unit 10.Switching Matrix 11.Memory 12.CPU Power Supply Unit The Power Supply unitgenerates the DC & ringer voltages for EPABX system. The input to the Power Supply may be 230 V AC or 24 V DC battery. Block diagram of the power supply Figure 5 Circuit Description : The AC line is fed to a step down transformer which gives out the voltages 10V & 28 Vrespectively.ThisisfedtotheVoltageregulatorthroughrectifier.Theregulator circuitconsistsofLM317ICs.Theregulatorcircuitapartfromprovidingdifferent voltages to the system charges the battery (when not in use) by 24 V DC supply. From the regulator voltage is supplied to various units of the system. In the absence of AC power the battery back up is used.ST2657 Scientech Technologies Pvt. Ltd.19Trunk Unit Trunk unit often termed as junction unit/card. It is interfaced to the lines coming from PSTN or Central exchange or the other exchange. Circuit diagram of Trunk circuit Figure 6Circuit Description : Theprotectivecircuitsprovidesprotectionagainstovervoltages&otherhazards.It consistsofbridgecircuitforpolarityprotection,similartothatofatelephone instrument. A 24 V Zener diode is used to maintain proper voltage. The optocoupler is used for an incoming ring detection. As the coupler gets the signal at its pin 1 the 5V appliedtopin5isextendedtopin4whichisusedasanindicationofanincoming ring.Thenafterdetectiontheexchangeservesitsownringtotheextension.When power is ON the relay is connected to NC terminal & hence it is not connected to any extension. When trunklineis accessed using 27 or 0. Theground pin of the relayis grounded & the relay switches & gets connected with the extension through switching matrix. The relay signal is generated by the control unit under the supervision of CPU. ST2657 Scientech Technologies Pvt. Ltd.20Experiment 2 Objective :To analyze & measure the ring detection phenomena Procedure : 1.Connect the trunk line or direct line to the Trunk 0 jack on the trainer. 2.Power On the trainer. 3.Make a call to the trunk line connected number. 4.Observe the LED glowing at TP 11. 5.Measure the voltage 5 V Approximately at TP11. Working :As the coupler gets the signal at its pin 1 the 5V applied to pin 5 is extended to pin 4 whichis used as an indication of an incoming ring& measured at TP11. By this the CPU gets the information through control unit. We conclude that if a subscriber calls anumber located in a different exchange .The ring is extended till it reaches the called subscriber exchange where the incoming ring is detected & extends its own ring till the subscriber end. ST2657 Scientech Technologies Pvt. Ltd.21Experiment 3 Objective :To analyze & measure the Trunk Relay Switching Procedure : 1.Connect the trunk line or direct line to the Trunk 0 jack on the trainer. 2.Measure the voltage at TP 1 it will be 12 VDC. 3.Dial 27 from any extension & listen to the dial tone. 4.NowmeasurethevoltageTP1againitwillbe0Voritisactuallygrounded& TP10 for 4V Approximately with LED glowing. Working : When power is On the relayis connected to NC terminal (Similar to normal Power off position) because its ground pin is not grounded & hence it is not connected to any extension.Whentrunklineisaccessedusing27 or 0Thegroundpinoftherelayis grounded & the relay switches & gets connected with the extension through switching matrix. The power for switching circuit is provided by Relay CTRL of control unit. Extension Unit Extension unit or Subscriber linecircuit orline card are thevarious terms used. It is thefirstcircuitthatisconnectedtothesubscriberamongthechainofcircuits.Itis usedasaninterfacebetweenindividualsubscribers(Extensions)lines&therestof thetelephoneexchange.Beingapartofbothoutsideandinsidetelecommunication network makes it susceptible to transients caused by atmospheric disturbances such as lightening & those induced by the AC mains like power cross apart from the physical hazards. So most of the line units incorporate protective circuits such as varistor etc. The line unit performs following functions : a.Protection b.Voltage (battery) Feed c.Supervision d.Ringing ST2657 Scientech Technologies Pvt. Ltd.22 Circuit diagram of line unit with trunk line Figure 7Circuit description : The surge protectors & hybrid transformers provides protection against over voltages. The hybrid transformers also help in impedance matching failure of which may result inecho.Avoltageof20V-60Visbeingfedtotheextensionloops.Specificallythis EPABX trainer feeds 24V On Hook & 8-12v (40 mA) Off Hook. When the power is off the extension 30 is directly connected to trunk 0, So that no calls are missed The calls will land only on this extension no line hunting is done. Theextensionlinehasanop-AmpwhichsensestheOn/OffHookcondition& passestheinformationtocontrolunit.Ringisextendedtoextensionsthroughline unit under the supervision. ST2657 Scientech Technologies Pvt. Ltd.23Experiment 4 Objective :Study of switching mechanism of relay Procedure : 1.Connect Trunk line to the trainer. 2.Power Off of the trainer.3.Lift the handset of the extension 30, listen to the dial tone.4.It will be a trunk line tone. 5.Now power on the trainer.6.Lift the handset of extension 30 again, Listen to the dial tone; it will be internal dial tone. 7.Now, in order to access trunk 0, dial 27 or 0. Working :ThenormallyclosedterminalsoftherelayRL1oftheextension30isconnected betweensubscribertelephoneinstrument&thetrunkline0.Soincaseofpower failure no calls are missed but calls cant be transferred. As soon as power is switched Ontherelayswitches.Nowanyswitchingthatsaccessingatrunklineorcalling otherextensionisdonebySwitchingMatrix(formoredetailsreferSwitching Section).ST2657 Scientech Technologies Pvt. Ltd.24Experiment 5 Objective :To analyze & measure the Off Hook detection Procedure :1.Measure the voltage at TP 2 & TP 3 it will be 24 V Approximately.2.Lift handset of the extension 30 & observe the LED glowing. 3.MeasurethevoltageagainatTP3itwill8-10V(whereasTP2remainsthe same). Working : Assoonastheextensiongoesoffhookthecurrentstartsflowinginthetelephone instrument which consists of voltage dropper or current limiter circuits as a result the voltage present in the line drops down to 8V.This changes the voltage at the negative terminal TP 3 of the op amp LM 393 thats IC 1(we already know voltage at TP 2 is 17VpositiveterminalofOpAmp),whichinturnchangesthestateoftheopamp. SinceLM393isanopencollectorOp-Ampthe5Vappliedtothecollectoris forwardedtothehookdetectioncircuit.WhichtakesitasanOffhookindication& the information is also fed to 8 bit bi directional data bus for CPU.ST2657 Scientech Technologies Pvt. Ltd.25Experiment 6 Objective :To analyze the working of the flash & its use Procedure : We already know that voltage at TP 3 is 24V On Hook. 1.Lift the handset of extension 30.2.MeasuretheOffHookvoltage8-10VatTP3&keepthemultimeter connected. 3.Operate the flash button on the telephone. 4.Observe the voltage fall & rise. Working : The flash button is provided on telephone instrument generates a pause. The duration ofthepausevariesfrombrandtobrand&alsowithcountries.Hereitgeneratesa pause of less than 0.5 sec supported by the EPABX. The flash facility is provided for transfer of call or to get to next call while hanging the first call on hold. Flash can also performed by tapping the switch. Some PSTN or central exchanges dont provide this facility. ST2657 Scientech Technologies Pvt. Ltd.26Experiment 7 Objective :Study of & analyze the amplified receiver signal Procedure : 1.Lift the handset of extension 30, listen to the dial tone. 2.Connect the Oscilloscope at TP 8, a low amplitude sine wave is observed. 3.Now connect at TP 6 & observe the amplified dial tone. Circuit diagram of an extension unit without trunk line Figure 8 ST2657 Scientech Technologies Pvt. Ltd.27Experiment 8 Objective : Study of switching mechanism of relay Procedure : 1.Power Off of the trainer.2.Lift the handset of the extension 32 and no dial tone is heard.3.Now power on the trainer.4.Lift the handset of extension 32 again, Listen to the dial tone. It will be internal dial tone. 5.Now, in order to access trunk 0, dial 27 or 0. Working : The extension 32 is not directly connected to any trunk line since its a 204 the trunk 0&1areconnectedtoextension30&31respectively.SointhepowerOff condition the relay RL2 is in normally closed terminals which are left open. When the powerisOntherelaytheoperates&getincontactwithcircuitry.Nowswitching will take place through matrix. Control Unit / Signal Processor Unit This unit consists of digital ICs. It serves as an interpreter between CPU & the analog circuitry.The functions performed are. a.ReceivingsupervisoryOn/OffHook,Flashsignals&decadicdialpulses from extension DC loops. b.Controllingringingtowardsextensions&providingautomaticringtripwhen extension goes off hook. c.Recognizing incoming ring from trunk/ direct lines. d.Controlling out pulsing on out going calls. e.Relay driving signals. Thesignalinginformationreceivedfromtheterminalcardisencodedinto bidirectional 8 bit data bus. ST2657 Scientech Technologies Pvt. Ltd.28 Figure 9 ST2657 Scientech Technologies Pvt. Ltd.29Experiment 9 Note:WehavealreadyperformedtheexperimentsrelatedtoRelaycontrol,Ring detection, Hook detection control in the trunk / Extension unit section. Objective : To analyze & measure the Ring Enable Signal Procedure :1.Lift the extension 30.2.Dial the extension Number 32. 3.Observe the LED glowing. 4.A signal can be observed or 4 VDC can be measured with multimeter. Working : TheRingcurrentsignalconsistingofhighvevoltage&ACRMSisallthetime generated in the exchange & forwarded through control signals. The signal generated by the Ring control unit after sensing the data bus signals is fed tooptocoupler(pin1)ofextensionunit.Thepin2ofthecouplerisconnectedwith hook detection pin. If theextensionis offhook a voltage of 4V will be available at pin 2 as a result the optocoupler will not conduct. Where as when the extension is On hooknovoltagewillbeavailableat pin2,Theoptocouplerwillconductassoonas signal is available at its pin 1. Decoder UnitThisunitalsotermedasdemultiplexerunititisoftenintegratedintheCPUunitor card. Block Diagram of decoder unit Figure 10 ST2657 Scientech Technologies Pvt. Ltd.30This unit provides the control & enable signal to the various units. The control signals relay driver, Intrce, Hook switch detection, Ringenable Touch tone rec 0 & 1, tones are signals kept high as soon as power is switched On. Where as the CE signals that chip enable signals are activated on particular function. The ISTB 0 & 1 are voltages provided to switching matrix through digital circuit.DTMF UnitThe Dual Tone Multi Frequency Unit it consists of DTMF receiver ICs 2 number the telephonekeypadisdividedbetweentwosetslower&higherfrequencies.Whena digit is pressed the two frequencies is sent out to reach the exchange. Note : More experiments of dialing can be performed with DTMF Telephone Trainer ST2654. Block diagram of DTMF unit Figure 11 At the exchange the DTMF unit decodes the frequencies with the help DTMF receiver ICs which consist of a low pass & high pass filter to differentiate the frequencies. AfterdetectiontheDTMFtonepairsaregivenasa4bitcodeto data busforCPU. The numbers of DTMF receivers are limited to the number of extensions served with the dial tone at the same time. ST2657 Scientech Technologies Pvt. Ltd.31Experiment 10 Objective :ToanalyzethattheDTMFreceiversarelimitedtonumberofdialtone extensions. (limitation of Space Division Switching) Procedure : 1.Power on the trainer. 2.Lift the handset of extension 30, hear the dial tone & observe the LED.3.TR0 glowing at the switching matrix, exchange is ready to accept the dial digits. (Maintain off hook) 4.Lift the handset of extension 31, hear the dial tone & observe the LED.5.TR1 glowing at the switching matrix, exchange is ready to accept the dial digits. (Maintain off hook) 6.Lift the handset of extension 32, hear the tone it will be a busy tone. Working :Thedialtoneisservedonlytotwoextensionsatthesametimeifathirdextension goes off hook simultaneously than it will be served a busy tone. Suppose if a dial tone isalsofedtothethirdextensiontheexchangeshouldalso be preparedto acceptthe dial digits & again to form a call .This in turn increases the circuitry & cost. ST2657 Scientech Technologies Pvt. Ltd.32Experiment 11 Objective :To analyze that dialing of DTMF digits sends out two frequencies. Procedure :1.Connect the CRO at TP 23. 2.Lift the handset of extension 30. 3.Dial any one digit say 3. 4.ObservetwofrequenciesontheCRO(keepthedigitpressedlongforbetter result). Showing two frequencies with digit pressed Figure 12 Clock Generation UnitThe 4 MHz clockgenerated by the crystal is divided by using the flip flop IC 74HC 74 (also served to CPU) & the frequency of 2 MHz is generated. The 2 MHz signal is also fed to dual BCD counter, which is used as an frequency divider. The output at pin 6is 200 KHzwhichis by dividing theinput frequency 2 MHz by 10 which is again fed to next counter in the same IC. So 200 KHz again divided by 4 to achieve 40- 50 KHz (Approximately) and also by 10 for 50 KHz. ST2657 Scientech Technologies Pvt. Ltd.33 Block Diagram of Clock / Tone generation unit Figure 13 This 20 KHz signal is fed to next counter as input the output of this counter is 200 Hz achieved by dividing 20 KHz by 10 for 2 KHz & again 2 KHz by 10. The 200 Hz is fed to next counter for dividing it by 5 to achieve final 40 Hz. This 40 Hz is fed to the ringer section for ring generation.The 40-50 KHz (Approximately) is given to the tone generation unit. Note : In some exchanges even 20 Hz is used a ringer frequency. Tone Generation UnitThe4050KHzsignalisgivenasinputtotwosynchronousbinarycountersThe countersU1givesoutasignalof3.3KHzthats40KHzdivided by12 = 3.3KHz. ThecounterU2outputisdividedby13&theoutputis3.07KHz (Approximately).Afterinverting through a Not gate both the signalare fed to a Dual ShiftRegisterU3,Serialinparallelout.Thefirstshiftregistergivesoutputby dividingby8thats420-460Hzapproximatelyasbusytonefrequency.Thesecond shift register output is by dividing by 8 thats 380 - 400 Hz thats dial tone frequency. TheLPFhas been connectedto the outputs after which the signalisamplified using an op- Amp. TheDT&BTaremixedtoproducetheRingBackTone(RBT)480Hzofafter amplification.Thethreetonesareeverytimegenerated&availableattheswitching matrix extended to the extensions whenever required.ST2657 Scientech Technologies Pvt. Ltd.34Experiment 12 Objective :To analyze the role & measure the frequency for ring generation Procedure :1.Measure the frequency at TP 22 for 20/40 Hz. 2.Operate the switch fault 1. 3.Lift the handset of 30 dial 31. 4.Observe only ring back tone is heard at 30 but no ringing at 31. ST2657 Scientech Technologies Pvt. Ltd.35Experiment 13 Objective :To analyze & measure that ring back tone is addition of dial tone & busy tone. Procedure :1.Observe the ring back tone at TP 30 as shown in figure 14. Showing Ring back Tone Figure 14 2.Measure with a frequency counter for 480 Hz. 3.Observe the DT at TP 34 with a CRO. 4.Operate the switch fault 3 (to remove DT from RBT). 5.Now again observe at TP 34 with CRO for DT No signal. 6.Now again observe at TP 30 & observe the change. 7.Lift the handset of extension 30 ( no dial tone because of switch fault). 8.Dial 31 & notice a change in the RBT. Similarly to remove BT operate the switch fault 2 observe at TP33. ST2657 Scientech Technologies Pvt. Ltd.36Experiment 14 Objective : To measure the frequencies of dial tone & busy tone. Procedure :1.ConnectthefrequencycounteratTP31tomeasureDTof380-400Hz Approximately. 2.ConnectthefrequencycounteratTP33tomeasureBTof430-460Hz Approximately. ST2657 Scientech Technologies Pvt. Ltd.37Experiment 15 Objective : To observe the amplified Dial Tone Procedure :1.Connect the CRO at TP 34 observe the signal as shown in figure 15. 2.Now , connect the CRO at TP 31 observe a amplified signal. Showing dial tone before amplification Figure 15 Showing amplified dial tone Figure 16 Music Circuit Itcanbecommerciallyavailablemelodytoneorvoicecircuit.Oritcanbewith recording facility to the subscriber for customized service. Like other tones this is also all the time generated in the exchange and extended to the required extension through switching matrix. ST2657 Scientech Technologies Pvt. Ltd.38Experiment 16 Objective :To analyze the music tone Procedure : 1.Lift the handset of extension 30, dial 31.2.Answer the 31, keep On hold. 3.Press the flash button on the telephone instrument of ext 30. 4.Hear the melody tone at extension 31, since its On hold. 5.Same is all the time visible at TP 32 by connecting CRO. Switching MatrixAcrosspointisusableforestablishingmorethanoneconnection.Itissharable among many subscribers. This sharing leads to a reduction in the number of switching elements required. Generallyanswitchingelementonceallotted,remainsdedicatedtoaconnectionfor its entire duration. As a result sharing of a cross point occurs from one connection to the next. At a time, a cross point is dedicated to one active speech circuit. A dedicated cross point is required because continuous analog speech waveform is passed through it in space division switching.ThecrosspointswitchingisachievedbyusingacombinationofICCD22100.It combinesa44arrayofcrosspointswitha4lineto16linedecoder&16latch circuits.Anyoneofthesixteentransmissiongates(crosspoints)canbeselectedby applying the appropriate four line address. TheselectedtransmissiongatecanbeturnedOn&Offbyapplyinglogic1or 0 respectively, to the data input & strobing the strobe input to a logic 1. Any number of transmission gates can be On simultaneously. Functional Diagram Figure 17 ST2657 Scientech Technologies Pvt. Ltd.39Switching Matrix Figure 18 Condition 0 : AllExtensionsareinoffhookposition.Wecansaythatswitchingmatrixisinidle condition.WhereasDialtone,RingbackTone,BusyTone,Musicarealltime generatedsignalsarewaitingfortheirrespectiveturnattheswitchingmatrixas shown in figure 19.Switching Matrix Figure 19 ST2657 Scientech Technologies Pvt. Ltd.40Condition 1 : Theextension31goesoffhook&thesubscriberisservedwiththedialtone&atthe sametimetheexchangeisreadytoreceivedialingsignals.Thepathisformedby closing the switch at the point of intersection at DT, TR0 ,EXT 31 as shown in figure 20. Switching Matrix Figure 20Condition 2 :If the Subscriber holds the extension off hook for more than the specified time period withoutdialingthen,theDT&TR0aredisconnected&BTisfedbyclosingthe switch as shown in figure 21. Switching Matrix Figure 21 ST2657 Scientech Technologies Pvt. Ltd.41Condition 3 : AfteroperatingHookswitchthesubscribergetsbackstheDT&TR0Similarto condition1.Diallingisaccepted&thecalledsubscriberextensionisringingasin figure 22. Switching Matrix Figure 22Condition 4 : Ongettingtheringextension32goesoffhook&aDCloopofdedicatedpathis formed between the extensions 30 & 32 as shown in figure 23. Switching Matrix Figure 23ST2657 Scientech Technologies Pvt. Ltd.42Condition 5 : The extension 30 & 32 are busy, Where as the 31 has accessed a trunk line 0 Switching Matrix Figure 24 Condition 6 : The extensions 30 & 32 are busy in conversation. Extension31isbusywithtrunkline.Thentheextension33goesoffhook&if subscriber tries any internal number it will end in busy tone BT. Where as the subscriber is free to access & call trunk lines in figure 25. Figure 25 ST2657 Scientech Technologies Pvt. Ltd.43Condition 7 : All extensions are On Hook position in figure 26. Switching Matrix Figure 26 Condition 8 : A call formation between extension 30 & 32, 31 &33 in figure 27. Switching Matrix Figure 27ST2657 Scientech Technologies Pvt. Ltd.44 Ringer UnitTheringingcurrentisallthetimegeneratedintheexchangeandextendedto subscriberwheneverringingisrequired.Theringingcurrentisa70/90VRMS, 20/40 Hz AC signals. +5 V Block diagram of ringer unit Figure 28 TheringerunitconsistsofahighnegativeDCvoltagegenerationcircuit-140to-150V.ThisisusedforgenerationofAC70V.Afrequencyof20/40Hzisalso provided to this unit from the clock generation unit. The ringing signal is available at pin4ofoptocoplerofeachextensioncircuit.Theringenablesignalunderthe supervision of CPU will make the coupler to conduct only if the extension is ON hook & no voltage is available at pin 2 of opto coupler. ST2657 Scientech Technologies Pvt. Ltd.45Experiment 17 Objective :To measure the high negative voltage & to analyze it is generated all the time. Procedure : 1.Switch On the trainer. 2.Connect the multimeter at TP 21.3.Measure the voltage -150V DC Approximately. ST2657 Scientech Technologies Pvt. Ltd.46Experiment 18 Objective :To measure the frequency & its role Procedure : 1.Connect the CRO at TP 22 measure the frequency 20 / 40 Hz. 2.Operate the switch fault 1 , 3.Now measure at TP 22 & no frequency is available. 4.Lift the handset of extension 30,dial 3.1 5.Observe that 30 will get ring back tone where as there is no ringing at 31. ST2657 Scientech Technologies Pvt. Ltd.47Experiment 19 Objective : To measure the ringing signal Procedure : 1.Connect the multimeter & measure at TP 20 for 70 V AC.2.Lift the handset of 30, dial 31 starts ringing if the handset is ON hook. Note :TheACsignalcanbemeasuredatthesubscriberendifDTMFTelephone Trainer ST2654 is connected. CPUTheCPUusedisZ80thirdgenerationsinglechipmicroprocessor.Itoffersmore efficientmemoryutilizationthancomparedtootherprocessors.Itworkswith8bit bidirectional data bus & 16 bit address bus. The Z 80 Processor requires only a single +5Vdcsupply&itseasytoincorporate.Alloutputsignalsarefullydecoded& timed to control standard memory or peripheral circuits. Figure 29 MemoryThe memories used are EEPROM & RAM. The512kbEEPROMstoresembeddedprogramusedforoperationofexchange& other necessary information. The CE chip enable signal of the memory is always kept high. TheRAM8kbmemoryisusedforstorageoperatingdatasuchasalarm,operating changes E.g. Ringing sequence, auto night mode etc. ST2657 Scientech Technologies Pvt. Ltd.48Software Experiments 1.Automatic Call Back on Busy ExtensionIf the called extension is busy, this feature automatically connects as soon as the calledextensiongetsfree.Onhearingabusytone,waitforafewseconds,for the dial tone to return. Dial # 13.Hang up. As soon as the called extensiongets free,your extension will ring.Lifthandset;you willhear aninternal ring tone. Wait for the called party to answer. Procedure : 1.Liftthehandsetofextension30&keepitoffhook(toactasbusyor engage). 2.Now use the extension 31 & dial the extension number 30. 3.A busy tone is heard, wait for dial tone to return. 4.Dial # 13.5.Hang Up. 6.As soon as the called extension 30 gets free so now keep back the handset On hook, observe extension 31 will ring. 7.Lift the handset of 31, soon the extension 30 will start ringing. 2.Do not disturb : If an extension user does not wish to be called, this feature allows the extension to prevent itself from being called. However, the extension user can call others. Lift handset and obtain dial tone, dial # 14.Hang up. Procedure : 1.Lift handset of extension 30.2.Dial # 14. 3.Hang up.4.Use any ext say extension 31.5.Dial 30. 6.The call will end with a busy tone & observe that no Ring Enable signal is generated for ext 30. 7.To cancel this feature, Lift handset of ext 30. 8.Dial # 0, Hang up. ST2657 Scientech Technologies Pvt. Ltd.493.Call transfer : Anyinternalcallreceived/originatedatanyextensioncanbetransferredfrom that extension to any other extension. Even a trunk call can be transferred within extensions. Oncethecallisformed,UseflashbuttonorHookFlash&heartone.Dialthe extensionnumbertowhichyouwanttotransferthecall.Waitfortheinternal ring tone. You may then hang up; the call will be transferred automatically. You may wait for an answer to announce the call and then hang up. Procedure : 1.Lift the extension 30 2.Dial 31, receive the call 3.Operate the flash button on any of the extension & dial 32. 4.Waitfortheinternalringtone,youmaythenhangup;thecallwillbe transferred automatically. 4.Call forwarding : This feature allows an extension user to receive calls at any other extension. 1.Lift the handset of the extension to be forwarded (diverted) say 30.2.Dial # 11 extension 31(to which calls are to be diverted). Disconnect. 3.Use extension 32, Dial 30 & observe the extension 31 to be ringing. 4.Cancellation of this feature is as follows : 5.Lift handset of extension 30 6.Dial # O, hang up. 5.Call Pick -up : If another extension is ringing, this feature allows the user to receive that call at hisownextensionwithout physically movingtotheringingextension.Liftthe handset of your extension and hear the dial tone, then just dial 8. Procedure : 1.Lift the handset of extension 30, dial 31. 2.Observe the 31 ringing. 3.Now lift 32 dial 8 for call pick up. 4.Now, call is formed between 30 & 32 extensions. ST2657 Scientech Technologies Pvt. Ltd.506.Follow me : Incomingcallscanbemadetofollowtheextensionuser.Inotherwordsthe extensionusercanuseanyextensiontoreceiveincomingcallsdirectedathis original extension. Lift handset where user wants to receive calls. Dial # 16 XY. (XY is the No. of the originalextension being used).All callsfor XY willnow ring at the extension from where the above code has been dialed. Procedure :1.Lift the handset of extension 31. 2.Dial # 16 30 (or any extension number). 3.Use extension 32, dial 30 observe all calls of 30 landing at extension 31. To cancel this featureDial # 17 30 from extension 31 7.Hot Line : TheHotLinefeaturewillgetactivatedassoonasthecallerpicksuphis handset; he need not dial any code. The called party's telephone/ Extension No. will be dialed automatically. Procedure :1.Lift the handset of extension 30. 2.Dial #12 32 (where 32 is the extension number). 3.hang up. 4.Lifthandsetofextension30,observehotlinefeatureactivatedand extension 32 ringing itself without dialing. 5.To cancel this feature operate as follows :6.Lift handset of extension 30, hear ring back tone.7.Wait till the other extension 32 picks up.8.Use flash button of extension 30, Dial # O 8.Conference If while conversing with an outside line or an extensionyou wish to arrange for a third party to conference, you may do it. Procedure: While conversing with party A use the hook-flash; Party A goes on hold. Listen to the dial toneand dial the Extension Number of party B. Speak to partyB& hook-flash to conference between yourself, party A and party B. RepeattheproceduretoextendtheconferencetopartyCandpartyDinthe same manner.ST2657 Scientech Technologies Pvt. Ltd.51Cancellation of all present Features (#0) If you wish to clear features such as Call Forwarding, Do not Disturb, Extension Privacy,LineQueuingetc.,youshouldliftthehandsetandonobtainingthe.: dial tone,' dial # O. Some Programming Experiments : The following points should be kept in mind, while programming. 1.The password should be keyed in before each programmingstep. The password is # * 1234. 2.Afterthecorrectpasswordiskeyedin,thedialtoneofthesystemwillreturn, there by indicating correct password entry. The wrong password will generate a busy tone. 3.While programming, all extensionsshould be in an "on hook" condition (not in use).except the one used for programming. Exchange Mode : a.NormalMode:Inthismodeanincomingcallonanyofthetrunklines willcause4extensionstoring,oneaftertheother.Thesequenceof ringing for each trunk line can be changed. Service Group Selection In the normal mode, an in-coming call on any of the trunk lines will make asetofextensionsringoneaftertheother.Eachextensionringsfor20 secondsbeforeanothertakesover.Thissetofextensions(max.4)canbe different for each trunk line and is called the Service Group for that trunk line. To program a service group dial: Password + 22 + Trk + Ex + Ex hang up. Trk = access code i.e. 27, 28 ...etc. Ex. = Extension. For example, if you want extension 31,33 and 35 to ring in sequence when there is an in-coming call on trunk No.27, then dial: Password + 22 + 27 + 31 + 33 +32 hang up. When thereisanincoming call on trunkline 27, thecall will first ringat extension 31. If it is busy it will automatically go to extension 33 which, if free, willstart ringing. Ifnobodyanswers for 20 seconds, the call willgo to extension 32, and then back to 31, and so on. Similarly, service groups can be set for other trunk lines as well. CareshouldbetakeninallocatingExtension.Nos.aspertheexchange model i.e., Nos. are 30, 31,32,33 . ST2657 Scientech Technologies Pvt. Ltd.52b.Night Mode : In this mode an in-coming call on any of the trunk lines will makespecifiedextensions(maximum4)ringsimultaneously.Wecan specify which extension should ring. To select either Normal or Night Mode, lift the handset and dial: Password + 10 +0/1 + Hang up. 100 will select Normal and 101 will select the Night Mode Night Ring Group : IfthesystemisintheNightmode,anin-comingcallonanytrunklinewillmake specifiedextensionsringsimultaneously.Thespecifiedextensionsarecalledthe Night Ring Group. To program lift the handset and dial: Password + 12 + Ex. + Ex. + Ex. + Ex. For example, if you want extensions 30, 32, 33 to ring while there is an incoming call on any of the trunks in the Night Mode, then dia1: Password + 12 + 30 + 32 + 33 + hang up Auto Night Mode : ThereisalsoanAutoNightModeSelection.Inthismodetheusercansetoffice timings.ThesystemwillconverttheoperationtoNightmodeafterofficehours automatically and will change to Normal Mode at the time of opening office. In order to set this, key in the following: Password + 11 + 0-6 + 0/1 + HH + MM + 0/1 + HH + MM0 : Sunday 1 : Monday 2 : Tuesday 3 : Wednesday 4 : Thursday 5 : Friday 6 : Saturday 0 : A.M. 1 : P.M. HH : Hours MM : Minutes For example if on Monday the working hours are between 9.30 AM to 5.00 PM then dialPassword + 11 + 1 + 0930 1 + 0500 ST2657 Scientech Technologies Pvt. Ltd.53Date Setting : To key-in date, dial : Password + 14 + YY + MM + DD + hang up. AboveFeaturesshouldonlybeusedifthesystemissupportedbyanuninterrupted power supply unit or a back-up. Time Setting : To key in the current time, dial:- Password + 13 + 0/1 + HH + MM + SS + Hang up. 0 : A.M. 1 : P.M. HH : Hours MM : Minutes SS : Seconds Forexample,ifthe currenttimeis15minutesand 45secondspast 3Oclockinthe afternoon, then dial : Password + 13+1+03+15+45+Hang up. Note : This sets the clock for the exchange and not for any extension.Date Setting : To key-in date, dial : Password + 14 + YY + MM + DD + hang up. Features describedaboveshould onlybeusedifthesystemissupported byanUPS (uninterrupted power 5uply unit) or a battery back-up pack. Setting of Alarm Clock [#18 + (0/1) + HH + MM] : Each extension can be pre-set to ring at a pre-determined time. This time can be set by lifting the receiver, dialing # 18 and then 0 if the alarm time is A.M. or 1 if the alarm time is P.M., after which the alarm time should De keyed-in. The extension will ring at the appointedtime. On lifting the receiver theuser will hear music. HH stands for hours and MM for minutes (2 digits must be used for each). For example, if the alarm is to be set for 3.15 PM then key-in # 13, 1, 03and 15. Note : In case the extensionis in use at 3.15 P.M. the alarm will ring afteryou go on hook. This feature should be used only when the Power Supply is uninterrupted or a proper Battery Back-up system is provided. MM should be rounded off to nearest 0 or 5 i.e 3.13 to 3.15 and 3.12 to 3.10. ST2657 Scientech Technologies Pvt. Ltd.54Denied Table : Thistabledefinestheareadialingcodesforlocal,95,STDorISDwhicharenot availablefordialingoutbyextensionsthatareinthedeniedmode.Thedenied number has to be added to the denied table, and then each ext has to be programmed for denied. Dial as follows : Password + 16 + Area Code + hang up. Area code = 95 or any STD code This will be added to denied table, now programming the ext to be denied Password+50+Ext.+ 0/1 0 : ALW 1 : DNY Note : Dialing password + 16* will clear the denied table. This must be done prior to programming the denied table. Barge-in Tone : IfAistalkingtoBandCwantstobargein,allthreewillhearawarningtone. However,if C'sextensionisinthe"Bargetoneoff'conditionthenCwillbeableto barge in without triggering a warning tone. This feature is programmed by dialing : Password + 54 Ex.+0/1+hang. 0 = barge-in tone off 1 = barge-in tone on Forexample,ifextension33istobegiventhefacilityofbarginginwithoutany warning, then dial : Password+ 54+33+0+hang up. If, later, this status is to be changed to barge-in tone on then key in:- Pass-word + 54+33+1+hang up. Note : Initial setting of this function is Barge-in tone On ST2657 Scientech Technologies Pvt. Ltd.55Barge in (#Ex) : Ifanextensionisfoundbusy,thisfeatureallowsthecallertointerruptthe conversationofthebusyextension.Thefeaturecanbeusedwithawarningtoneor without a warning tone. To use this feature operate as follows :Lift handset, dial Extension No. and on hearing a busy tone, disconnect. Lift hand set & hear dial tone. Dial # Extension Number. Wait for one second. (If the feature is with a warning tone you will hear the same and if without a warning tone you will not).Interrupt conversation. Extension Out-of-Service :If any extensionhas not been connected to the system then it is deemed to be "out of service". This status must be programmed into the exchange otherwise the system will continue to give an internal ring tone if these extensions are dialed. To program dial : Password + 50 + Ex + 0/1 + hang up. Ex = Extension 0 = Out of service 1 = In service For example if extension 33 is out - of - service, then dial: Password + 50 + 33 + 0 Now, if anybody dials 33 he will get an engaged tone. Whensubsequently,aninstrumentisconnectedtoextension33thenits"inservice" status needs to he programmed, .and is done by dialing : Password + 50 + 33 + 1 + hang up ST2657 Scientech Technologies Pvt. Ltd.56Test Point Details TP 1 :12 VDC normal & when accessed 0V and short to GND. TP 2 :18V TP 3 :On Hook 24V / Off Hook 8-10V TP 4 :18V TP 5:On Hook 24V/Off Hook 8-10 V TP 6 :On Hook 0 V/ Off Hook 2 V & DT Sine wave, Speech Signals. TP 7 :On Hook 0V / Off Hook 2V & DT Sine wave, Speech Signals. TP 8 :On Hook 24V/Off Hook 16 V TP 9 :On Hook 24V/Off Hook 16V TP 10 :4-5 V DC When Trunk AccessedTP 11:Incoming Call 2-4 V DC TP 12:On Hook 0 VDC /Off Hook 4-5 VDCTP 13:On Hook 0 VDC /Off Hook 4-5 VDC TP 14:On Hook 0 VDC /Off Hook 4-5 VDC TP 15:On Hook 0 VDC /Off Hook 4-5 VDC TP 16 to 19:On Hook / Off Hook 0V / Incoming Call 4 V TP 20:60 70 V RMS 40 Hz AC Signal (All Time) TP 21:130 VDC TP 22:20-40 Hz Ringer Frequency TP 23 24:DTMF Frequency when digit pressed TP 25 :Speech signals when accessed, 8V Constant On/Off Hook TP 26-29:On Hook 8 V, Off Hook- 8 VDC & DT Sine wave,Speech signals. TP 30 :Ring Back Tone 500 Hz (460-480 Hz) Approximately TP 31:Dial Tone 2V Sine wave Amplified 384 Hz TP 32:Music Tone740 Hz Approximately TP 33 :Busy Tone Sine wave 416 Hz TP 34:Dial Tone 1V Sine wave before Amp 384 Hz TP 35:2 MHz Clock TP 36:Sine wave 4 MHz ST2657 Scientech Technologies Pvt. Ltd.57Glossary Central Office : Refers to either a telephone company switching centre or the type of telephone switch used in a telephone company switching centre.DualToneMultifrequency:Asignalingsystemthatsendspairsofaudio frequencies to represent digits on a telephone keypad. It is often used interchangeably with the term Touchtone. EPABX/PABX:(ElectronicPrivateAutomaticBranchExchange)isaprivately ownedtelephoneswitchingsystemforhandlingmultipletelephonelineswithout having to pay the PSTN Company to lease each line separately.ErlangB:AformuladevelopedbyA.K.Erlang,widelyusedtodeterminethe number oftrunksrequiredtohandleaknowncallingload duringaonehour period. Theformulaassumesthatifcallersgetbusysignals,theygoawayforever,neverto retry (lost calls cleared). Since some callers retry, ErlangB can underestimate trunks required. However, Erlang B is generally accurate in situations with few busy signals. ErlangC:Calculatespredictedwaitingtimes(delay)basedonthreethings:the number of servers (reps); the number of people waiting to be served (callers); and the average amount of time it takes to serve each person. It can also predict the resources required to keep waiting times within targeted limits. ErlangC assumesno lost calls or busy signals, so it has a tendency to overestimate staff required.Erlang,A.K.:ADanishengineerwhoworkedfortheCopenhagenTelephone Companyintheearly1900sanddevelopedErlangB,ErlangCandothertelephone traffic engineering formulas. Erlang:Onehouroftelephonetrafficinanhouroftime.Forexample,ifcircuits carry 120 minutes of traffic in an hour, that's two Erlangs. Gateway : A server dedicated to providing access to a network. GradeofService:Theprobabilitythatacallwillnotbeconnectedtoasystem because all trunks are busy. Grade of service is often expressed as "p.01" meaning 1% of callswillbe"blocked."Sometimes,gradeofserviceisusedinterchangeablywith service level, but the two terms have different meanings. See Service Level. ST2657 Scientech Technologies Pvt. Ltd.58FAQ Q. Why the trainer is mimic based rather than circuitry based? TheEPABXisacombinationofAnalogcomponents,DigitalICs,Mechanical relaysetc,understandingcircuitflow&co-ordinationbetweenvariousunits would have been difficult task with a circuitry based trainer.Q. Why only the 204 configuration system? The204configurationwasadoptedasacompromisebetweenthe104&306 configurations.Sincelowconfigurationsaremostbasic&higharejust duplications of the circuits.Q. Why there is not much with the CPU? The CPU used in this EPABX is Z80 processor or Atmel or even it can be a PC justtosupervisethetask.DedicatingmoreonZ80orprocessorwouldhave turned the EPABX system to an Embedded Training System. Where aslearning kits are easily available for the same.Note : More FAQ will be added after feedback. ST2657 Scientech Technologies Pvt. Ltd.59Warranty 1)We guarantee the product against all manufacturing defects for 24 months from the date of sale by us or through our dealers. Consumables like dry cell etc. are not covered under warranty.2)The guarantee will become void, if a)The product is not operated as per the instruction givenin the operating manual.b)The agreed payment terms and other conditions of sale are not followed. c)The customer resells the instrument to another party. d)Any attempt is made to service and modify the instrument. 3)The non-working of the product is to be communicated to us immediately giving fulldetailsofthecomplaintsanddefectsnoticedspecificallymentioningthe type, serial number of the product and date of purchase etc. 4)The repair work will be carried out, provided the product is dispatched securely packed and insured. The transportation charges shall be borne by the customer. List of Accessories 1.Patch Cord 16 (DC Red)...........................................................................1 No. 2.Patch Cord 16 (DC Black)...................................................................... 2 Nos. 3.AC Adaptor ...............................................................................................1 No. 4.Mains Cords ..............................................................................................1 No. 5.Telephone Instruments............................................................................. 4 Nos. 6.e-Manual (CD)...........................................................................................1 No. Updated on 25-06-2008