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A

Summer Training Report

On

Telecom Equipment Technology

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ABSTRACT

Today telephone has become an integral part of our lives. It is the most widely used

communication device in the world. Owing to its immense popularity and widespread use, there

arises a need for call recording devices, which find application in call centres, stock broking

firms, police, offices, homes, etc. Here we are describing a call recorder that uses very few

components. But in order to understand its working, one must first have the basic knowledge of

standard telephone wiring and a stereo plug.

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INDEX

SR.No TOPIC PAGE NO.

1. COMPANY PROFILE

2. PUSH BUTTON TELEPHONE(PBT)3. ELECTRONICS PRIVATE AUTOMATIC BRANCH

EXCHANGE(EPABX)

4. FAX MACHINE

5. PROJECT ON TELEPHONE CALL RECORDER

6. REFRENCES

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Chapter No. 1

Company Profile

Centre for Development of Advanced Computing , Mohali (erstwhile CEDTI) wasestablished in May 1989, as a Scientific Society of the Ministry of Communications and

Information Technology (MCIT), Government of India. In December 2002, CEDTI, Mohali

was merged with C-DAC, another society of MCIT with a primary mandate for R&D.

C-DAC Mohali, an ISO 9001:2000 certified institute, is a Research & Development

institution for design, development and deployment of world class IT and electronics solutions

for economic and human advancements. C-DAC Mohali is a dynamic, growing institution,

focused on the development of cutting edge solutions in the following domains:

Health Informatics

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Multilingual Technologies

Professional Electronics

Software Technologies

Cyber Forensics and Security

Multimedia Technologies

C-DAC Mohali operates from its own impressive building having a coverearea of

approximately 4300 sq. mts. The centre is located in the ELTOP (Electronics Town of Punjab)

Complex amidst a large number of industries, manelproducts relating to computers, peripherals,

communication equipment offering a great professional challenge to the faculty and staff of the

Centre.

Two decades ago C-DAC Mohali (erstwhile CEDTI Mohali) started as a leading HR

developer and training Institute for Information Technology (IT) sector in the northern region. It

has continued to grow and offer various courses. The Centre has earned a brand for quality

training programmes. Along with various diploma courses, C-DAC Mohali also offers high-end

courses like M.Tech in VLSI as well as ME in Electronic Product Design Technology (EPDT).

Short term value added courses designed for knowledge based skill development have also

received enormous response.

Present R&D activities cover projects on Health Informatics including telemedicine, e-

Governance, e-Security, BOSS / Linux Server, Language technology, Black Box for

automobiles and Various RFID based Applications.

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Chapter No 2

PUSH BUTTON TELEPHONE:

After going through this chapter a student should be able to clearly grasp:

1.The principal of operation of a telephone instrument and various signalling technique in

telephone communication.

2.The two types telephone sets based on dialing technique DTMF & decadic respectively and

understand the difference between the two.

3.The inner technical details of a push button description of a ringer circuit based on IC-1240.

4.The structure of dialing pad key matrix and its working.

TELEPHONE INSTRUMENT

In the telephone network the subscribers are given telephone instruments (also called telephone

sets).

The instrument performs large number of functions. Some of the important functions are :

1. It requests the use of telephone system when the handset is lifted.

2. It indicates that system is ready for use by receiving dial tone.

3. It transferred the dialed number.

4. It indicate the status of call( ringing, busy etc.).

5. It indicate the presence of incoming call by ringing a bell.

6. It converts voice signal to electrical signal for transmission and electrical signal to audible

speech signal for reception.

7. It signals the end of the call.

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Diagram of push button telephone

IN PBT SOME IMPORTANT DATA:

On Hook voltage -48V DC

Off Hook voltage -6V to -12V

Ringing voltage 75V RMS AC, 25 Hz

Loop current 30mA to 60mA

Telephone resistance 300 - 600

Block diagram of push button telephone

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TWO TYPE OF CONDITION IN PBT:

1. ON HOOK

2. OFF HOOK

When handset is put on the base at that time phone is on hook condition when handset is pickup

from the base the phone is in off hook condition. When phone in off hook condition it make the

loop and loop current flow. When phone is in off hook condition then it not makes the loop.

When phone in on hook condition then ringer section is active when phone is in off hook

condition then dialer section is active.

In telecommunication we use the RJ11 register jack. But in networking we use the RJ45 register

jack.

TYPS OF RJ11:

1. 6P2C (6 pin 2 connection)

2. 6P4C (6 pin 4 connection)

3. 6P6C(6 pin 6 connection)

TYPES OF DIALING:

1. Pulse dialing

2. Dual tone multifrequency dialing

PULSE DIALING

Most telephone sets used dial pulsing. Dialing in signalling from the telephone to the network.

The rotator dial opens and closes the loop circuit at a timed rate. The no of pulses is determined

how for the dial is rotated before releasing it. The no of pulses in the pulse train represent the

digit value except for 0 which is represented by 10 pulses. Two successive digits are separated

by inter-digit gap. The pulse rate is usually 10 pulses per second. The inter-digit gap is 800ms.

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Inter-digit gap is also known as inter- digit pulse (IDP). For example if we press a digit 3 we

will get 3 pulses. In pulse dialing make break ratio is 1:2.

DUAL TONE MULTIFREQUENCY(DTMF) DIALING

This type of dialing is also known as touch tone dialing. This is a faster dialing technique as

compared to pulse dialling. The dial is replaced by an array of push buttons. Touching a button

generates a Tone which is a combination of two frequencies, one from the lower band and

one from the upper band. For example, when button no 5 is pushed the transmitting frequencies

are 770Hz and 1336Hz. The frequencies in DTMF are carefully selected so that these are not

confused with other tone on the line. The DTMF tones are present for a minimum specified

time(50ms or more) so that these are detected properly at the exchange.

This scheme offers following advantages

1. Decreased dialing time.

2. Use of solid state electronics.

3. Can be used for end to end signaling.

4. Reduce local exchange requirement.

5. It can be easily integrated with modern electronic exchanges.

THREE TYPE OF IC IN PUSH BUTTON TELEPHONE:

1. RINGER IC

2. SPEECH IC

3. DIALER IC

RINGER IC

Mostly we use ringer IC-1240. But in some time we use ringer IC-2418.

Function of ringer IC

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1. To generate the audible ring.

2. To control the volume.

SPEECH IC

Mostly we use speech IC 1060/1061 18 pin. But in some time we use IC 1062 16 pin and 3280

14 pin.

Function of speech IC

1. Provides connection between the user and exchange anything or signal which has to

travel from one telephone to exchange or to other telephone has to pass through this

circuit.

2. Receiving amplification means adjustment of the gain of the signal received from the

other end.

3. Sending gain is also to be adjusted to make it appropriated according to the microphone

used.

4. Side tone is a small part of signal to be send which is audible to the sender himself. This

again is to be make appropriate .

5. Two to four wire conversion.

DIALER IC

Mostly we used the dialer IC 3561/ 2560 in pulse mode but in DTMF we use dialer IC 91214B.

Function of dialer IC

1. Accept the key being pressed on the key pad by shorting row and column.

2. Decode the key which is pressed on the key pad.

3. Generate the pulses /tone according to the key pressed.

4. Generate the mute signal to cease the operation of speech IC during dialing.

5. It stores the processed no in memory up to 32 digit.

6. In pulse dialing it will generate the required IDP and make break ratio.

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Chapter No.3

ELECTRONICS PRIVATE AUTOMATIC BRANCH EXCHANGE (EPABX)

ITRODUCTION:

1. EPABX is an electronic switching device whose basic fuction is internal and external

communication with PSTN(public switched telephone networks).

2. Its configuration tells about it connecting capability with CO line and subscriber.

3. For example, EPABX 308 means we can connect 3 telephone line and 8 subscriber to

EPABX.

When a call comes into the EPABX from an outside trunk line, it is either routed

directly to a telephone extension or to a console. The phone rings which is answered by

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an attendant. The incoming call is connected to the required destination extension by

dialing the number .

DIAGRAM OF EPABX

TYPE OF EPABX

1. ANALOG EPABX

2. DIGITAL EPABX

ANALOG EPABX

Some important points of ANALOG EPABX

1. Space division multiplexing(SDM)

2. For less distance

3. Efficiency 65%

4. Blocking

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DIGITAL EPABX

Some important points of DIGITAL EPABX

1. Time division multiplexing (TDM)

2. For more distance

3. Non Blocking

4. Efficiency 90%

Main Parts of EPABX

1. MDF

2. SLIC

3. CO LINE CKT

4. CPU

5. CROSS POINT SWITCH

6. TGU

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FEATURES OF EPABX:

1. CLASS OF SERVICE: This feature allow the users to be combined into

different groups, each with access to different features ,and with different

external calling capabilities.

2. DO NOT DISTURB: This feature facilitates an extension to block all incoming

calls, internal or external, to it. This feature is activated by dialing the feature is

activated by dialing the feature code. When this is activated, system will route

the calls to the calls to the available operator and we use the #14 code at the

source.

3. CALL TRANSFER: For call transfer we use flash+ extension no of destination.

4. REDIAL: For the redial we dial *.

5. BARGE IN: For barge in we dial #+extension no.

6. AUTOCALL BACK: For auto call back we dial #13.

7. EXTENSION PRIVACY: For extension privacy we dial #15.

8. CALL FORWARDING: For call forwarding we dial #11+extension no of

destination.

9. CANCELLATION: For cancellation we dial #0.

10. CALL PICK UP: For call pick we dial 8.

11. FOLLOW ME: For follow me we dial #16+extension no. of source.

12. CANCELLATION: for cancellation we dial #17+extension no. of source.

13. CALL CAMP ON: For call camp on we dial flash +#+extension no.

14. PICKING UP CAMPED CALL: Flash##

15. CONFERENCE:Flash+Dial1st extension no.+ flash

Flash +Dial 2nd extension no.+ flash

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Chapter No. 4

FAX

FAR AWAY XEROX

Facsimile is one of the original electrical engineering arts, invented by Alexander Bain in

1842. Many characteristics of signaling appeared first in facsimile. In its long development,

facsimile has served as a mother art, spawing a variety of devices and methods.

NEED OF FAX:

To transmit and receive the text document between two distinct point using telephone line

network we use the device called FAX.

OR

In other words if two photocopier Xerox machine can be connected with telephone line we also

called it REMOTE OFFICE COPIER.

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Block Diagram of FAX machine

FEATURES OF FAX MACHINE:

1. Built in dial

2. One touch dailing

3. Speed dialing

4. Automatic re-dialing

5. Alternate re-dialing

6. Delayed transmission

7. Automatic voice/data switch

8. Document feeder

9. Dual access(phone+fax)

10. Automatic paper cutting

11. Multiple paper role

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12. Copier option

13. Automatic fall back

14. Automatic error correction

15. Transmit terminal identification

16. Broadcast transmission

17. Polling

18. Contrast control

19. Half tone transmission

20. RS-232 port/interface attach with computer

21. Transmission report

22. Communication journal

23. Power backup

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TYPES OF FAX MACHINE:

Generally fax machine divided into four groups

1. G1 Fax machine: G1 fax machine was brought in 1983 and it takes very long time as

compared to other fax machine for the transmission of document.

2. G2 Fax machine: G2 fax machine takes less time (3 min) as compared to G1 fax

machine for the transmission of document.

3. G3 Fax machine: the types of machine used now days are the example of G3 Fax

machine. These machines are connected with analog network and it takes few seconds

for the transmission of document.

4. G4 Fax machine: these machines are connected with digital network (ISDN) and it takes

less time than above all machines.

FAX MACHINE INVOLVES FOLLOWING STEP FOR THE TRANSMISSION OF

DOCUMENT:

1. Optical scanning

2. Encoding

3. Recording

4. Modulation

5. Signal processing

6. Transmission

7. Demodulation

8. Decoding

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SENSOR:

Three type of sensors are used in fax machine:

1. Door sensor

2. Document sensor

3. Paper sensor

APPLICATION SPECIFIED INTEGRATED CIRCUIT (ASIC):

ASIC is the heart of the fax machine. It performs the following functions

1. Control the operation of document transmission.

2. Control the operation of document reception.

3. Control the auto answering operation.

4. Control the delay sending operation.

5. Control the polling.

6. Control the dialing

STEPS FOR TRANSMISION AND RECEVING IN FAX MACHINE:

Load the document

Signal goes to ASIC

Sub routine from EPROM

Instruction loaded to RAM

ASIC will initialize the stepper motor

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CIS power switch on

Pass through second sensor

Motor stops and power is switched off

Document is get ready for the transmission

Directly get signal from ASIC

It has CPU

Convert the serial data into parallel

Data applied to decoder

Parallel data converted into seven segment display

Hence indication will be displayed on LCD panel

Document get ready at the receiver end

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SUMMER

TRAINING

PROJECT REPORT

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SUMMER TRAINING PROJECT REPORT

ON

TELEPHONE CALL RECORDER

SUBMITTED TO: SUBMITTED BY:Mrs. Brijinder kaur Abhay Kumar Mishra

Mr. Yarmia Anuj Kalundia

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Declaration

I Abhay kumar mishra hereby declare that the project entitled TELEPHONE CALL

RECORDER embodied in this project has been carried by us is an original work. We also

declare that not part of it has been submitted for any other degree previously

Date:- Abhay kumar mishra

Place:- C-DAC Mohali

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Certificate

This is to certify that Abhay kumar mishra student of B.Tech(E.C) has done their summer

training at Academic & Consultancy Service Division C-DAC Mohali from 11-07-11 to 19-08-

11.

The project work entitled TELEPHONE CALL RECORDER embodies the original work by

them during their summer training period.

During the duration of project they have put their sincere efforts & shown a great deal of

analysis.

Course co-ordinator

Mrs. Brijinder kaur

DCS-Division

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Acknowledgement

It is our pleasure to take this opportunity to thank all those who helped us directly or indirectly

in the preparation of this project.

We would like to place a record & acknowledge the works of all those great authors whose

works we have used in this project.

We appreciate the way that our lab assistance deals us for preparation of the project. Though

this project we came to know about various components used in electronics.

Through these 45 days of training we gain lot & heartily thanks to our teachers for their kind

appreciation in preparation of projects & their sincere nature. Here we would like to place a

record the works co-operation of all teachers & faculty members.

Finally we must thanks & give credit to Mrs. Brijinder kaur & Yarmia Anuj kalundia for his

never ending of his chase.

Abhay kumar mishra

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TABLE OF COTENTS

ABSTRACT

HOW IT WORKS

BLOCK DIAGRAM

COMPONENT LIST

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C

ABSTRACT

Today telephone has become an integral part of our lives. It is the most widely used

communication device in the world. Owing to its immense popularity and widespread use, there

arises a need for call recording devices, which find application in call centres, stock broking

firms, police, offices, homes, etc. Here we are describing a call recorder that uses very few

components. But in order to understand its working, one must first have the basic knowledge of

standard telephone wiring and a stereo plug.

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sss

HOW IT WORKS

In India, landline telephones primarily use RJ11 wiring, which has two wires

tip and ring. While tip is the positive wire, ring is the negative one. And together they

complete the telephone circuit. In a telephone line, voltage between tip and ring is around 48V

DC when handset is on the cradle (idle line). In order to ring the phone for an incoming call, a

20Hz AC current of around 90V is superimposed over the DC voltage already present in the

idle line. The negative wire from the phone line goes to IN1, while the positive wire goes

toIN2. Further, the negative wire from OUT1 and the positive wire from OUT2 are connected

to the phone. All the resistors used are 0.25W carbon film resistors and all the capacitors used

are rated for 250V or more.

RJ 11 configuration

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The negative terminal of To AUX IN is connected to pin 1 of the stereo jack while the

positive terminal is connected to pins 2 and 3 of the stereo jack. This stereo jack, in turn, is

connected to the AUX IN of any recording device, such as computer, audio cassette player, CD

player, DVD player, etc. Here we shall be connecting it to a computer. When a call comes in,

around 90V AC current at 20Hz is superimposed over the DC voltage already present in the

idle line. This current is converted into DC by the diodes and fed to resistor R1, which reduces

its magnitude and feeds it to LED1. The current is further reduced in magnitude by the resistor

R2 and fed to the right and left channels of the stereo jack, which are connected to the AUX IN

port of a computer.

Pin configuration ofstereo jac

Any audio recording software, such as AVS audio recorder (available at:

http://www.avs4you.com/AVSAudio- Recorder.aspx), Audacity audio recorder

(http://audacity.sourceforge. net/), or audio recorder (http://www. Audio

tool.net/audio_recorder_for _free.html), can be used to record the call. When a call comes in,

one needs to launch the audio recording software and start recording. For phone recording,

simply connect the stereo jack to the AUX IN port of the PC. Install the audacity audio recorder

(different versions are available for free for different operating systems athttp://audacity.

sourceforge.net/) on your PC. Run the executable audacity file. In the main window, you will

find a dropdown box in the top right corner. From this box, select the AUX option. Now we are

ready to record any call.

http://www.avs4you.com/AVSAudio-http://audacity.sourceforge/http://www/http://audacity/http://audacity/http://www.avs4you.com/AVSAudio-http://audacity.sourceforge/http://www/http://audacity/

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Call recorder circuit

As soon as a call comes in, press the record button found in the

audacity main window and then pick up the telephone receiver and answer the call. Press the

stop button once the call ends. Now go to the file menu and select the Export as WAV option

and save the file in a desired location. You may change the value of resistor R2 if you want to

change the output volume. We can use a variable resistor in series with R2 to vary the volume

of the output. The recorded audio clip can be edited using different options in the audacity

software. we can assemble the circuit on a general-purpose PCB and enclose it in a small

cabinet. Use an RJ11 connector and stereo jack for connecting the telephone set and computer

(for call recording). Telephone cords can be used to connect to the phone line and the circuit.

Use of a shielded cable is recommended to reduce disturbances in the recording. These can also

be reduced by increasing the value of R2 to about 15 kilo-ohms.

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Component list

Component name Quantity

Diode (IN4001) 4

Resistor (33) 1

Resistor (12K) 1

Capacitor (12pf) 1

Capacitor (33pf) 1

Led 1

Stereo Jack (3.5mm) 1

RJ 11 2

Telephone cable 2 mtr.

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References:

www.electronicsforu.com

www.epanorma.net

www.authorstream.com

www.wikipedia.com

www.google.com

http://www.electronicsforu.com/http://www.epanorma.net/http://www.authorstream.com/http://www.wikipedia.com/http://www.google.com/http://www.electronicsforu.com/http://www.epanorma.net/http://www.authorstream.com/http://www.wikipedia.com/http://www.google.com/