Guided ByMr. S. Srinivas (M.Tech)

Assistant professor

(Sr.Grade)

Presented byPresented by

CH.GANESH CH.GANESH M.Tech (WMC) 1st M.Tech (WMC) 1st

Year Year Roll No : Roll No :

13881D650113881D6501

What is Touch Tone Dial Telephone Components of Telecommunication setEssential componentsTouch Tone Dial Telephone SystemDTMF (Dual-Tone Multi-Frequency )DTMF Keypad Basic Telephone call ProcedureAdvantages, Applications of Telephone systemConclusionReferences

PRASENTATION OVERVIEW

Components of a Telephone Sets

1. Transmitter

2. Receiver

3. Electrical network for equalization

4. Associated circuitry

to control side tone level

to regulate signal power

5.Magnet

6.Carbon grains

7.Dry Cell Battery

THE TELEPHONE LINE DIAGRAMTHE TELEPHONE LINE DIAGRAM

Essential Components

Ringer CircuitOn/Off Hook CircuitEqualizer circuitSpeaker/receiverMicrophoneHybrid networkDialing circuit

Touch Tone Dial Telephone

1. The Touch Tone telephone is a communication device that makes use of a form of telephone.

• The connecting of a call from one phone to another phone that is known as Dual-Tone Multi-Frequency (DTMF).

• With the rotary dial phones commonly used through the 1970s. A simple telephone keypad.

• Replaced the rotary dial on the newer touch tone units that became the industry standard for both cell phones and land lines.

Dual-Tone Multi-Frequency (DTMF)

1. Dual-tone multi-frequency (DTMF) signaling is used for telephone signaling over the line in the voice-frequency band to the call switching center

2. DTMF passes transparently over normal two-way radio channels, narrow-band or wide-band

3. DTMF, is a method for instructing a telephone switching system of the telephone number to be dialed, or to issue commands to switching systems or related telephony equipment.

4. The DTMF system uses eight different frequency signals transmitted in pairs to represent sixteen different numbers, symbols and letters.

Telephone Communication System

DTMF Keypad

3. The signal is encoded as a pair of sinusoidal (sine wave) tones from the table below which are mixed with each other.

4. The keypad is on your phone, the telephone company's "Central Office" equipment knows what numbers you are dialing by these tones, and will switch your call accordingly.

1. Press the buttons on the keypad, a connection is made that generates two tones at the same time. A "Row" tone and a "Column" tone. which is also referred to as tone dialing.

2. The original keypads had inside, so each button activated two contacts.

DTMF DATA O/P Signal flow

Out put data enables

Signal flow

Step 1: Calling station goes off hook

Step 2: Switching machine returns an audible dial

tone to the calling station

Step 3: Caller dials the destination #

Step 4: Switching machine removes the dial tone

from the loop

Step 5: Switch interprets the # and locates the local

loop for the destination #

BASIC TELEPHONE CALL

Step 6: Switch check the destination for the

DC current

If off hook, busy signal sends to the calling station

If on hook, ringing signal and ring back signal will

be sent

Step 7: When destination answers the call, it

completes the loop causing DC current to

flow.

BASIC TELEPHONE CALL

Advantages   1. Helps to build a healthy relationship.

2. Being a bridge for people being miles away.

3. Saves time, money and energy.

4. Immediate medium to contact one another

and pass urgent messages.

5. Helps to file complaint against anyone

without identity and save

6. Gives life for thousands of telemarketers

APPLICATIONS:

Telephone dialing. Data entry. Credit checking. Voice mail system control. Electronic mail system. Telephone banking system

CONCLUSION:

A. Seven different frequencies (697 Hz, 770 Hz, 852 Hz, 94Hz,

1209 Hz, 1336 Hz, 1477 Hz) in DTMF system were tested.

B. These signals are used in touch-tone telephone call signaling as

well as many other areas such as interactive control

applications, telephone banking and pager systems.

C. The system has been developed in Mat lab.

References1. J.Bellamy,Digital telephony,2nd edition, John Wiley and sons.

2. Achyut S. God bole, Data communications & Networks, Tata McGraw hill, India.

3. B.A.Forouzan ,Data Communication & Networking,3rdEdition, Tata McGraw Hill

Thanking you