st – 53 - 122.252.243.98122.252.243.98/departments/snt/camtech notes/emergency... ·...

CAMTECH/S/2002/EC/SER-4 1

Emergency Communicationfor TCM/WTM

ST – 53L E S S O N – P L A N

DURATION: 06 DAYS (EQUIPMENT COURSE)

DESCRIPTION: EMERGENCY COMMUNICATION

STAGE : TCM / WTM

CONTENTSSl No. TOPIC Theo Practical Theo Equipment &

Instrument Toolsused

1. Use of Portable Controltelephone & megaphone

3 3 OHP,BlackBoard,WallChart

Equipment &Instrument, Toolsused

2. Mobile and Portable VHF Set 4 4 -DO- -DO-3. Use of PA System 4 4 -DO- -DO-4. Use of Magneto Phone

,Selective calling telephone andfield service cables.

3 3 -DO- -DO-

5. Items used in Break Down(Communication)

3 3 -DO- -DO-

6. Immarsat, Iridium Telephone 2 2 -DO- -DO-7. Remote Subscriber Unit

(Extending auto telephone toaccident site)

3 3 -DO- -DO-

8. Visit to break down special 2 2 -DO- -DO-24 Hrs. 24 Hrs.




DURATION : 04 DAYS (INITIAL COURSE)


STAGE : TCM / WTM






2. Mobile and Portable VHF Set 2 2 -DO- -DO-3. Use of PA System 3 2 -DO- -DO-4. Use of Magneto Phone

Selective calling telephone andfield service cables.

2 2 -DO- -DO-


2 2 -DO- -DO-

6. Immarsat, Iridium Telephone 2 2 -DO- -DO-7. Remote Subscriber Unit


2 2 -DO- -DO-

8. Visit to break down special 1 2 -DO- -DO-Total 16 Hrs. 16 Hrs.




DURATION : 01 DAYS (REFRESHER COURSE)


STAGE : TCM / WTM






2. Mobile and Portable VHF Set 1 1 -DO- -DO-3. Use of PA System 1 - -DO- -DO-4. Use of Magneto Phone

Selective calling telephone andfield service cables.

1 - -DO- -DO-


1 - -DO- -DO-

6. Immarsat, Iridium Telephone - - -DO- -DO-7. Remote Subscriber Unit


1 - -DO- -DO-

8. Visit to break down special - - -DO- -DO-Total 06 Hrs. 02 Hrs.



ST – 53DESCRIPTION: EMERGENCY COMMUNICATION

DURATION

06 Days for Equipment Course02 days for Initial Course

01 day for refresher course

STAGE : TCM / WTM

CONTENTS

1. Use of Portable Control telephone & megaphone

2. Mobile and Portable VHF Set

3. Use of PA System

4. Use of Magneto Phone Selective calling telephone

5. Items used in Break Down (Communication)

6. Immarsat, Iridium Telephone

7. Remote Subscriber Unit (Extending auto telephone to accident site)

8. Visit to break down special

DRAWING:

From Page No. to Page No.



EMERGENCY COMMUNICATION

Emergency Communication in Railway operation is one of the most essentialrequirements of Railway Telecommunications. The working of these circuit from the place ofaccidents or mid-section is different in each system.

The comparison of important aspects of emergency communication available onvarious type of train control communication are given below:

Type of Control CommunicationSlNo.

Aspect of emergenciesCommunication O/H U/G RE OFC 18 GHz

1. No. Of Circuits available 1 or 2 1 More than2

More than2

2. Quality of service Average Good Very Good Very Good3. Availability Availability

at siteAvailabilityat a dist. Of500 Mt.

Availabilityat site

Availabilityat site

4. Cost of Implication Moderate Moderate Moderate High

Indian Railways has provided different types of communication far from radiorequirements based upon infrastructure available. Existing Wireless Communication systemon Indian Railways mainly for emergency Annexure :-

Railway Section FrequenciesC.R Nagpur-Itarsi-Bhusawal 314 – 322 MHz ( 4 Chl )S.E.R Nagpur – Durg

Rajkharswan – Gua314 – 322 MHz ( 4 Chl.)136 – 174 MHz (Duplex)(Trunk Radio)

N.R New Delhi – Mughal Sarai 314 – 322 MHzW.R Mumbai Central – Ahmedabad 160 .45 MHz (Simplex)S.R Chennai – Gudur -DO-N.R New Delhi – Ambala -DO-

1. USE OF PORTABLE CONTROL TELEPHONE

(A) Every Train shall be provided with a provided with a portable control / portableemergency telephone in the break van.

(B) Every Portable control telephone shall be accompanied by L-14 diagram and a setof poles suitable for making connection with overhead lines.

(C) Emergency Socket boxes are provided along the track at intervals of 0.9 Km. To1.2 Km. Portable Emergency Telephones are to be plugged into the emergencysocket boxes for establishing an emergency communication with TPC. Thesockets for emergency telephone are also provided near signal cabins, sub-sectionalizing and sectioning posts, insulated overlaps and feeding posts.

All the equipments may be tested by an Inspector periodically as ordered by theadministration.



2W – Portable Telephone

This telephone consists of following vital components.

1. Transmitter, 2. Receiver, 3. PTT switch 4. Battery (3V), 5. Induction coil,6. Capacitor 7. Diodes.

1. Transmitter and Receiver for speech transmitting and receiving purpose.2. PTT Switch – It is used to feed battery to transmitter. It avoids drainage of voltage

in case of listening.3. Induction Coil : It acts as auto transformer and have two functions – I) Anti-side

tone suppression, ii) Impedance matching.4. Capacitor – for avoiding D.C loop formation during hooking.5. Battery – 3 V dry cell are used for energisation of transmitter.6. Diodes :- They are used for acoustic shock absorption.



4W- Emergency Telephone

The portable control telephone used in RE area containing two coils. One isTrans coil and another is Receive Coil. The telephone uses a carbon transmitter andreceiver. A PTT switch is provided for a feed of 3 V during speech.

The outgoing voice the person using the telephone has to press the presselswitch. This enables 3 V battery supply for transmitter speech current s are fed to theprimary of Trans coil where Secondary is fed at the points T-T of the 6-pin plug ofPin 1 & 6 are TX speech are available .

For incoming speech from Head quarters is available at the Pins R-R i.e. 2 & 5of the 6-Pin plug. This is fed to Primary of Receive Coil, which after passing throughsecondary of the receiving coil is fed to the receiver of the portable telephone thereceiving coil is fed to the receiver of the portable telephone.

Calling from an accident site by a Guard or a driver can establish anemergency call and convey message to the Traction Power Controller of the saiddivision.



Megaphone

Megaphone is also known as Bell-hailer. It is small P.A system arrangementmainly used in accident site. It is a portable type unit which have in-built microphone,hand speaker, and amplifier arrangement. There is a compact 12 V battery supply inthis unit. It can be used in accident site for a gathering of 80 – 90 people to addressthem.

MEGAPHONE

2. Mobile and Portable V.H.F set .

Mobile & Portable V.H.F set is essential communication arrangement duringemergency. These may simplex or duplex. Normally simplex V.H.F set is widely usedas I) Emergency Communication between accident or derailment site to nearest Rly.Station 2) Emergency Communication between stations to avoid total interruption.

Now adays all V.H.F sets are frequency synthesised. The frequencyprogramming is very easy in this type than crystal set, which are earlier models.

V.H.F transmitters and receivers located at frequent intervals by the side of thetrack may provide communication with the V.H.F transmitter & receiver provided onthe train. The nearest microwave station can be used to provide the long distance link.



V.H.F Mobile transreceiver for different models (Meltron make) are

RT.415 - MK II – 08 (68 to 88 MHz)RT.415 - MK II – 16 A (136 to 150 MHz)RT.415 - MK II - 16 B ( 150 to 174 MHz)

Similarly V.H.F model Transreceiver for (SIMOCO make) are also used.Power output of the sets is normally 25 Watts. Simplex V.H.F set has only onefrequency in each channel. So in simplex set PTT (Press to talk) switch must bepressed during voice transmission and during listening PTT is to be released.Accessories of V.H.F Mobile set are 1) Antenna (may be GP or Yagi), 2) Feeder wire,3) Speaker, 4) Microphone 5) Battery 12 V DC may be available from 12V carbattery) or 230 / 12 V DC Power supply unit.

3. USE OF P.A. SYSTEM

P.A System is extensively used in Rly. In different fields like in RailwayPlatform Marshalling and shorting Yards, Conference room Meeting room SeminarHall, Stadium etc. Moreover it plays an important role in accident /derailment site.

The components for P.A System are mainly – 1. Microphone, 2. Loudspeaker,3. Amplifier, etc.

Microphone are mainly classified –

1) According to impedance2) Mode of operation.3) Mode of application.

The main types of microphone are-

1) Carbon type2) Capacitor type3) Moving Coil type4) Ribbon type5) Crystal type

Loud speakers are classified in two types-

1) Core type2) Horn type

Amplifiers are selected according to the following factors-

1) Capacity of Amplifiers.2) Input .3) Gain.4) Sensitivity.5) Frequency response.6) Constant voltage response.



A) Installation is governed mainly by the following factors :-1) Size.2) Type.3) Location.4) Audience to be covered.5) Type of sound to be produced.6) Desired & psychological reaction on audience.

Indoor operation:

Installation of P.A System for such operation is done keeping in view of the followingfactors:-

A) Siting of Microphone , Amplifier , Loud speaker.B) Quality and level of reproduction.C) Microphone.D) Amplifiers.E) Loud speakers.

Microphone should be directional type in order to minimum acoustic feed back,Moving coil type preferable be used being robust and suitable for rough handling.

Outdoor P.A.System :-

For outdoor operation such as Railway platform, station complexes, Loco sheds,outdoor station and similarly noise level keeping in view the audience of absorption.

Loudspeakers :-a) Its number, power value, location height etc. decided as areas

coverage so that proper intensity of sound reproduced ismaintained.

b) One type loudspeakers with metal mountings can be used a largernumbers evenly distributed array to cover Rly. Platform. Horn typeloudspeakers are suited for open platforms and halls with high roof.

PAGING AND TALK BACK SYSTEM.

Paging may be described as a process by which a speaker’s voice is transmitted toseveral loudspeakers simultaneously or selectively.

In marshalling yards, the yardmaster can locate any of the yard staff by means ofpaging system. A paging arrangement with simultaneous calling features.

In big location paging operator can quickly locate personnel in a selector area.



4. USE OF MAGNETO TELEPHONE

Magneto Telephone is instrument, which consist of self generating (75 V AC) ringingfacilities along with self-power supply (3V to 4.5 V) for speech. It has no connection with CB.Exchange. It can be extended upto max. distance of 5 Km or more as per transmission line

Application: It is used for short distance point-to-point physical line communication such as

i) Both side cabin to station Master.ii) Level crossing gate to station Master.iii) Signal cabin to signal cabin.iv) Cabin to gatev) I.O.W (water works) to Pumping Station

Station where Main Exchange lines are not terminated.

i) Cable Hut to Cable Hut.ii) Point to point communication for accident site.iii) As an intercom within some building.

FS Cable : FS cable is known as Field Service cable. It is used for outdoor applications forproviding communication on temporary basis in energies like Rly. Accidents, floods, cyclones etc.They can be substituted for overhead lines also. The specification is “Field service Cable” Singlecore twin size (7/0.0148”) (0.375 mm) 150 V /440V grade PVC insulated and PVC sheathed as perIS : 694 (Part –I) – 1964.

Slective Calling Telephone :

Selective calling is a system by which a number of subscribers can be connected in timeinternal facilated with omnibus circuit. The telephone uses in this system is known as selective callingTelephone.

Another selective calling Telephone may be used as a MASTER-SLAVE system. Master cancall by selective calling system can be employed by digit coding system.

This is designed to work on parallel mode in a 2-wire omnibus speech circuit and based onvoice Frequency Signalling using Dual Tone Multi Frequency signals (DTMF) for operation, havingfacilities for Selective calling and communication between 12 such units connected in parallel.

A Desk type DTMF telephone consists of one Telephone and a Power pack. This telephoneconsists of 2-way voice communication circuit suitable for 2 wire operation and can be used asselective calling Telephone. It is having DTMF code generator , code Transmitter and receiver, codereception and decoder circuits, ringing and ring back tone transmission circuits all housed inside thetelephone.

A power pack is supplied alongwith this telephone which works from 110v to 230 v AC andthe output ranges from 6V DC to 12V DC which is suitable for the telephone.



Specifications:

A. Signalling Mode : By DTMF signaling as per CCITT standard.B. Transmitting Media : U/G cable O/H lines, OFC and Microwave.C. Current Consumption : Idle Mode : 15 mA.

Conversation : 25 mA.D. Siganlling Level : 0 dBm.E. Speech Level : -5 dBm.F. Line attenuation : : Max. 20 dB.G. Codes : : 12 Codes ( Like 1,2,3,4,……)H. Code setting : Each telephone can be set to any of the above 12 codes by a

DIP switch provided inside .I. Operating Voltage : 6 to 12 V DC.

Operation :

Hand set is lifted from Hook.Press a suitable number button for giving ring to that telephone whose code is set for thatnumber.Called telephone will get ring and the caller telephone will get a ring back tone.A LED will glow in the called telephone alongwith the ringing of the Buzzer. This LED willremain glowing till the handset is lifted. When handset of the receiver telephone is lifted , LED will lit OFF.Now conversation will start.At the end of conversation, place the handsets on the hook.If a 3rd telephone is required to be brought into conversation press the code of the 3rd

telephone. 3rd telephone will get ring and by lifting the handset it can join that conversation.

5. ITEMS USED IN BREAK DOWN/ART VAN FOR COMMUNICATIONPURPOSE

The Breakdown /ART Van is supposed to move through out the division as well as otherDivision also both in RE & Non-RE traction area. So the equipment is provided to sought both for RE& Non-RE area.

Generally the following items are used in accident side for reliable communication and tohelp restoration of train movement vide RLY BOARD LETTER NO. 88/TELE/WE/2/MISC DT.17/05/1988.

Sl No. ITEMS Quantity Remarks1. Battery operated 20 Watts. Amplifier 1 No. For all ART.2. Transistorised Megaphone (Bell-hailer/Loud hailer) 3 Nos. All ART3. Microphone Moving coil with connector. 1No. -DO-4. Floor stand for Microphone 1No. -DO-5. Loud speaker Reflex horn 4 Nos. -DO-6. Multimeter (Sanwa) AVO 1 No. -DO-7. Tool kit junior with tools 1 kit. -DO-8. Wire twin trusted flexible for connecting Amplifier

and Loud speaker600 Mtrs. -DO-

9. Portable Telephones (Emergency telephone) (RE &Non-RE)

2 + 2 Nos. -DO-

10. Cable for used in portable Telephone (3/7 pairPolyethylene Insulated)

500 + 500Mts.

-DO-

11. 2/4-wire speech conversion unit (in a wooden box)complete with 12 V battery.

1 No. -DO-



Sl No. ITEMS Quantity Remarks12. Field telephone 2 wire (In a box) 1No. -DO-13. Field telephone 4 W (In a wooden box) 1 No. -DO-14. Field telephone cable 1000 Mts. -DO-15. Tent/small portable tent complete 1 No. -DO-16. Portable Telephone hook and Pole arrangement for

Overhead wire connection2 Nos. -DO-

18. Manila Rope with Pulley blocks 2 sets -DO-19. Insulators 12 Nos. -DO-20. 100 ibs GI wire 2 Span 40 Mtr -DO-21. Stalks for Telecom/Signal overhead alignment 6 Nos. -DO-22. Tilley lamps 2 Nos. -DO-23. PVC insulated 2 crore Power Cable 1100 V grade

with solid seven strand copper conductor..200 Mts. -DO-

24. Emergency Control amplifier For Emergencytelephone.

2 Nos. -DO-

25. Portable Collapsible Mast (For VHF set) 2 Nos. -DO-26. a) Walkie Talkie sets (2 watt) VHF with 3 battery

charger, 2 spare sets of battery as well as localsupply at base station.b) Emergency Generator to charge the batteries.

8 Nos.

1 No.

-DO-

-DO-

6. IRIDIUM TELEPHONE

IRIDIUM system is a satellite based wireless personal communications networkdesigned to permit any type of telephone transmission - Voice, Paging FAX data to reach itsdestination on earth. Remote project engineers, Business professionals, Remote projectengineers, Business professional under developed areas, disaster relief teams with convenient– hand held telephone with a single world wide number.

Now the system works :- When an IRIDIUM telephone is activated the nearestsatellite in conjunction with the Iridium network automatically will determine accountvalidity and location of the user . The subscriber will select among cellular or satellitetransmission alternatives depending upon the compatibility and system availability todispatch a call. If the local cellular system is unavoidable or not compatible the telephone willcommunicate directly with a satellite overhead. The call then will be transferred from satelliteto satellite through the network to its destination either another IRIDIUM telephone or anIRIDIUM of road station IRIDIUM telephone system network with land based fixed orwireless infrastructure world wide.

SPECIFIC APPLICATION AREAS IN RAILWAYS:

IRIDIUM services and portable handset can be used for communications between thecontrol room and the driver or the driver and guardroom. This would help to find out theexact status of the train and also help to communicate any important message still inbetween stations. Help mobile teams during field surveys and track testing. Rlys are oftenused in surveys and track testing. Rlys are often called during disaster/ relief operations. Insuch cases Iridium services would provide an effective and in expensive way to keep in touchwith the outside world. Rly. Personnel often cross over to places where the conventionalcommunication services fail the obvious choice would be satellite based communicationservices.



BENEFITS OF IRIDIUM SERVICES

Global coverage : The system enables communication from any point on earth.

Mobility : Light weight and as easily portable as a cellular phone.

Reliability : Due to reduced dependence on terrestrial infrastructure and the presence of in Orbit spare satellites, Iridium system is extensively reliable.

No User license: Subscription possible without any regulatory requirement of obtaining licenses or special permission to use the systems.

PSTN & Cellular connectivity: System is inter connected to PSTN & Cellular networks (Via PSTN) across the world.

Local currency Billing : Billing will be done in the local currency from where the services are subscribed.

Secure communication : The system uses GSM protocol which is a digital standard ensuing completely secure communication. No installation / Maintenance requirements. Easy redeployment.

7. REMOTE SUBSCRIBER UNIT ( EXTENDING AUTO TELEPHONE IN ACCIDENT SITE)

Remote subscriber unit is a VHF or UHF based duplex communication system whichcab be used for establishing communication from a remote area like an accident / derailmentsite to the Divisional HQ. In Railway. An auto telephone at the remote Zonal end (accidentsite) can be provided with the help of following instrument for setting up communication.

1. Duplex trans received set 2 NOS. (One at exchange end & another at remoteend).

2. G.P/Yagi antenna at the end to be filled with suitable height by coaxial cable.3. Interface unit.4. Push button type telephone – 1. No. (at Remote end).

VHF for duplex transreceiver, which consists of one Transmitter and one Receiverportion. Working 12 V DC/ 230 V AC Power supply.

The transmitting power output of this equip. is 20 Watts (approx.)

Antenna used for this set is GP or Yagi type of interface card that can be work asDuplex Telephone Interface, Duplex phone patch and E&M signaling card (Both 2 wire and4 wire).

Transreceiver must be programmed for Tx frequency & Rx frequency of its operation.



CONNECTION PROCEDURE

The device connecting cable has total nos. 15-pairs female D-connectors DUXend and 15 Pin male D-connector on the other end connect the 15 Pin Male Dconnector “RADIO CONN” connects on the UPP. Connect the cable marked as RX tothe RX connector accessible from the rear side at the transreciver unit and connect thecable marked as TX-to-TX connector of radio.

CONNECTION FOR PHONE PATCH (EXCHANGE END)

The two jumpers 2W / PP inside the UPP is to the damaged for thisconfiguration to the position “PP’.

Telephone Line or EPABX line should be and must be connected to RJ 11connector “Line” on the back panel of the UPP and only to this connector in case ofDuplex Phone Patch.

Connection for Telephone Instrument Interface (Subscriber end) – TelephoneInstrument connection has to be made in TEL INT in case of Telephone Interfaceonly.

Connection for 2-W E&M Interface Two jumpers 2-W/PP inside the UPP is tobe changed for this configuration to the position 2W.

The two wire audio line from exchange is to be connected at ‘Green’ wire ofthe 9 pin D connector cable from rear side of “E&M” connector of UPP.

OPERATION OF DUPLEX PHONE PATCH TO TELEPHONE INTERFACE LINK

Connect the telephone line/EPABX line to the Phone Patch & the telephoneinstrument to the Telephone Instrument Interface.

PATCH TO INTERFACE CONNECTION

Telephone

EPBAXOR MUX

WITHE&MCARD

INT

TX

RX

INT

TX

RX



8. VISIT TO BREAK DOWN /ART VAN

Periodical visit to a break down special/ART Van is very important role for efficient& failure free maintenance of the communication equipment provided in Break Down/ARTVan.

Concern Supervisory & artisan staff should visit /check the emergencytelecommunication items once in a month (minimum) and as well as after every return ofbreak down special from accident /de-railment site.

The Inspection to be recorded jointly along with In charge of Relief Train ofMechanical department.

Some of the important communication items which are to be inspected efficiently areappended below:

1) Emergency Portable telephone 4W/2W. The condition of the pole and the leadwire of 2W portable telephone intactness to be inspected.

2) 25 Watts. VHF sets, 5 watt & 2Watt Walkie-Talkie set to be checked. Thereshould be sufficient nos. of Walkie-Talkie sets.

3) Auto telephone.4) Intactness of 500 + 500 mtrs. Interruption cable for extension of telephone line

from emergency socket or station.5) Battery charger and portable generator set.6) VHF Duplex set for providing auto telephone accident site from nearest

Microwave repeater Station.7) All Spare battery set.8) Bell-hailer etc.



DO’S

1. Always check the battery condition of 2W & 4W Portable Set before using insection.

2. Line capacitor (2 µ F) is to be tested properly before using.

3. Continuity of the hook wire 2W PT set to be tested.

4. Battery of 25 watt Portable VHF set kept in full charged condition in idlecondition.

5. In case of 25 Watt VHF set at the time of Antenna installation, kept sufficientdistance from High Tension Line.

6. Magneto telephone, Megaphone which is kept at Relief Train for emergencypurpose, should be checked periodically.

7. Battery wire for VHF Set as thick as possible.

DON’TS

1. Don’t switch on the 25 Watt VHF set without connecting antenna.

2. Don’t allow to entry the moisture or water inside the Radio Equipment.

3. Don’t press PTT button without connecting antenna of Walkie-Talkie Set.



RECORD SHEET



EXPERIMENT IN LAND LINE COMMUNIOCATION

Purpose: Study of 4 W / RE Emergency Portable Telephone.

APPARATUS USED:

Theory: This is a 4-W Portable Telephone and is used to communicate with thecontroller from the Section during emergencies. This is also used by Traction Department formaintenance purpose of 25KV O/H Traction alignment. This telephone work through the“Emergency Circuit” which is similar to 4-W control circuit without signaling facility to callthe controller. These emergency circuits have number of tapping at an interval of every 0.8Km to 1.0 Km along the Railway track and terminated on special sockets mounted on shortrail posts. This 4-W telephone can be plugged to those sockets and communication isestablished with the Traction Power Controller who normally attends the Emergency call.

PROCEDURE: 1.Identify the following parts:

a) Hand set, b) 6-W Cord, c) 4-way Cord, d) Battery container, e) Trans and ReceiveTransformer.

2. Trace the circuit and note the details of connections made to the 4-way cord and terminal Strips mentioning colour code. Draw diagram to show the interconnections.

3. Trace the interconnections between 6-pin plug and terminal strips and draw the diagram to show connections.

4. Check the battery and examine it is OK or not.

5. Insert the 6-pin plug of two telephones in two sockets to make conversation. Drawsketches to show trans and receive to patch.



REVIEW QUESTIONS:

1. Why 6-pin plug is provided ?2. What are the common faults occurring in this telephone ?3. Draw diagram to show the derivation joint for providing emergency socket tapping.

EXPERIMENT IN LAND LINE COMMUNICATION

Purpose: Study of Railway Portable Telephone for Overhead Control.

APPARATUS USED:

Theory: This type of telephone is used in time of emergency to establishcommunication from any point on section of two-wire overhead control circuit. This isconnected to the line by means of portable telephone pole, which has two hooks to clip on theline wire.

The working principle of the telephone is just like the magneto telephone. Thegenerator and bell of the magneto telephone is not provided here.

PROCEDURE: 1. Open the metal cover of the telephone by removing four numbers screws on the cover.2. Open the mouthpiece and earpiece of the HMT and check interconnection between

microphone and receiver.3. Check the battery voltage with 10 Ohms /1W resistor and down the result. What will be

the tolerable voltage drop of each cell when tested with 10 Ohms resistor?4. Examine the interconnection between the microphone receiver and terminal strip

connected by 4-way cord.Draw sketch to show the interconnection.

5. Before hooking pole, the condenser should be checked.6. Assemble the telephone by putting the back cover and by the screws.



REVIEW QUESTION :

1.Explain with simplified circuit diagram the incoming and outgoing speech circuit.

2. Why the junction diodes are provided?

3. What are the functions of line capacitor of 2 microfarad and pressel switch?

4. What are the faults normally appearing in this type of telephone? How will you proceed tolocalise and rectify them?

EXPERIMENT IN LAND LINE COMMUNICATION

Purpose: Study of Magneto Telephone

APPARATUS USED:

PROCEDURE: 1. Dismantle the telephone and identify the following parts: Moulded Case, Cradle rest

Cradle switch Base plate, Generator Handle, Generators, Terminal Rosette, Terminalstrip, Bell.

2. Open the mouthpiece and note the connections of the Cord to the Handset and terminalstrip, Mention colour code. Draw the diagram.

3. Trace the following circuit from the simplified circuit diagram:a) Incoming Ring:b) Outgoing Ring:c) Outgoing Speech:d) Incoming Speech:

4. Examine the generator and bell carefully, Particularly notching the cut-out of thegenerator

5. Examine the inductive coil. Draw a diagram and showing a counting of the numbers ofthe induction coil and also note down the value of resistance between taps 1 & 2, 3 &4and 5 &6 of the induction coil.

6. Measure the transmitter current with 3 v battery and draw diagram with Sanwa meterfor measuring current.

7. Reassemble the telephone.



Review Question :

1. Draw the symbol of the following.

a) Cell b) Battery c) Magneto Belld) D.C Buzzere) D.C Bellf) A.C Buzzerg) Magneto Generatorh) Cradle switch contact.



DIAGRAMOF

EMERGENCY COMMUNICATIONSrl No. Description

1. 2/4 W Portable Emergency Control Telephone Box2. 2Watt VHF Set

st – 53 - 122.252.243.98122.252.243.98/departments/snt/camtech notes/emergency... ·...

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