18-03-2011, 04:38 PM
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INTRODUCTION
IVRS is an important development in the field of interactivecommunication which makes use of the most modern technology availabletoday. IVRS is a unique blend of both the communication field and the softwarefield, incorporating the best features of both these streams of technology. IVRSis an electronic device through which information is available related to anytopic about a particular organization with the help of telephone lines anywhere inthe world.IVRS provides a friendly and faster self service alternative to speakingwith customer service agents. It finds a large scale use in enquiry systems ofrailways, banks, universities, tourism, industry etc. It is the easiest and mostflexible mode of interactive communication because pressing a few numbers onthe telephone set provides the user with a wide range of information on the topicdesired. IVRS reduces the cost of servicing customers.
IVRS BLOCK DIAGRAMIVRS- INTERACTIVE VOICE RESPONSE SYSTEM
The IVRS on the whole consists of the user telephone, the telephoneconnection between the user and the IVRS and the personal computer whichstores the data base. The interactive voice response system consists of thefollowing parts.
HARDWARE SECTION
1. Relay: For switching between the ring detector and the DTMF decoder.
2. Ring detector: To detect the presence of incoming calls.
3. DTMF decoder: To convert the DTMF tones to 4 bit BCD codes.
4. Micro controller: To accept the BCD calls, process them and transmitthem serially to the PC.
5. Level Translator: To provide the interface between PC and microcontroller.
6. Personal Computer: To store the data base and to carry out the text tospeech conversion.
7. Audio Amplifier: To provide audio amplification to standard output and toact as a buffer between the telephone line and sound card.
SOFTWARE SELECTION
1. Visual Basics 6.02. Oracle 8.03. Microsoft Agent
OPERATIONS OF IVRS
The user dials the phone number connected to the IVRS. The call istaken over by the IVRS after a delay of 12 seconds during which the call can beattended by the operator. After 12 seconds if the ring detector output is low, it isensured that the phone has not been picked up by the operator. Themicrocontroller then switches the relay to the DTMF and sends a signal via RS232 to the pc to run the wave file welcoming the user to the IVRS. The user isalso informed of the various codes present in the system, which the user dial inorder to access the necessary information.Thirty seconds are given to the user to press the codes, failure ofwhich results in switch back of the relay. The DTMF decoder converts the codespressed by the user to BCD. It is then pressed to the input pins of themicrocontroller and is stored in the microcontroller memory. After these codeshave been received, they are transmitted serially to the serial port of the PC viamax232 IC. Any hardware failure in transmission falls in the lightning of a LEDand the relay is switched back.The serial port of the PC is continually polled by the software usedsuch as Visual Basics and Microsoft Agent program and the received code wordsare put in the text box from the input buffer. The received personal identificationnumber (PIN) is compared with the stored data base to determine the result. Thecorresponding wave file is played by the sound blaster card. It is coupled to thetelephone line through the Audio Amplifier, which is connected between thesound blaster and the telephone line to amplify the blaster output, drive thetelephone line acts as the buffer for sound blaster.
DIFFERENT PARTS OF IVRS
a) MICRO CONTROLLERTHE ROLE OF MICRO CONTROLLER
The 8751 is the heart of the IVRS system. It controls the operation ofvarious parts of the IVRS system. When a telephone call is detected by the ringdetector, the micro controller switches the relay to the DTMF and sends a signalto the PC via RS 232 to run the wave file welcoming the user to the IVRS. Thenumber given by the user is decoded by the DTMF IC and is stored in thememory of the microcontroller. The code stored in the microcontroller is send tothe serial port. If any hardware failure occurs, it is the microcontroller which istaking necessary measures. The IVRS system makes use of a stand by computerso as to working 24hrs a day for customer satisfaction. In these cases themicrocontroller switches from the first computer to the second.
THE BASIC FEATURES
A microcontroller is meant to read data, perform limited calculationson the data and control its environment based on those calculations. Themicrocontroller consists of an 8-bit CPU in addition to RAM of 128 bytes, ROM,parallel I/0, serial I/0, counters, clock circuits etc, the EEPROM has a memory of0 to 4kb. There are four register banks with 8 registers each. The control registersused are TCON, TMOD, SCON, PCON, IP and IE. The program counter is 16bit while the status word and stack pointer is 8 bit. The 8751 has 4 parallel I/0ports. Hence the dual ports of these may be used as general I/O digital lines.Asystem clock generator using an external crystal and two external capacitors provide the required clock for the microcontroller. There are 5 INTERRUPTsources used by 8751 and each can be listed under any of the priority levels. The5 interrupts are listed below.
b) RING DETECTOR
he ring detector is connected directly to the telephone line throughthe relay which is controlled by microcontroller (8751). The function of the ringdetector is to detect if the telephone is ringing or not.The ring detector consists of op-amp LM 311 which acts as acomparator to convert 98 V (rms, 130 Vpp) ring signal to –5V (low level) stepsignal for the microcontroller’s INTO pin. The output of the comparator goeshigh when the operator picks up the telephone provided along with the IVRS.The presence of the ring detector output for 5 sec enables the micro controller toswitch the relay to the dual tone multi frequency (DTMF 8870). The capacitorC1 blocks incoming DC and resistors RA and RB are the voltage dividers toreduce the incoming voltage of 13VPP to 15V. Diode D passes only the positive half of the sine wave during which C2 gets charged to maximum value and actsas the DC value for the input signal which triggers the comparator. This chargedoes not get discharged easily due to high resistance R3, R4 and R5 are used asvoltage dividers to provide reference voltage of 2.5V to pin 2 of LM 311.
INTRODUCTION
IVRS is an important development in the field of interactivecommunication which makes use of the most modern technology availabletoday. IVRS is a unique blend of both the communication field and the softwarefield, incorporating the best features of both these streams of technology. IVRSis an electronic device through which information is available related to anytopic about a particular organization with the help of telephone lines anywhere inthe world.IVRS provides a friendly and faster self service alternative to speakingwith customer service agents. It finds a large scale use in enquiry systems ofrailways, banks, universities, tourism, industry etc. It is the easiest and mostflexible mode of interactive communication because pressing a few numbers onthe telephone set provides the user with a wide range of information on the topicdesired. IVRS reduces the cost of servicing customers.
IVRS BLOCK DIAGRAMIVRS- INTERACTIVE VOICE RESPONSE SYSTEM
The IVRS on the whole consists of the user telephone, the telephoneconnection between the user and the IVRS and the personal computer whichstores the data base. The interactive voice response system consists of thefollowing parts.
HARDWARE SECTION
1. Relay: For switching between the ring detector and the DTMF decoder.
2. Ring detector: To detect the presence of incoming calls.
3. DTMF decoder: To convert the DTMF tones to 4 bit BCD codes.
4. Micro controller: To accept the BCD calls, process them and transmitthem serially to the PC.
5. Level Translator: To provide the interface between PC and microcontroller.
6. Personal Computer: To store the data base and to carry out the text tospeech conversion.
7. Audio Amplifier: To provide audio amplification to standard output and toact as a buffer between the telephone line and sound card.
SOFTWARE SELECTION
1. Visual Basics 6.02. Oracle 8.03. Microsoft Agent
OPERATIONS OF IVRS
The user dials the phone number connected to the IVRS. The call istaken over by the IVRS after a delay of 12 seconds during which the call can beattended by the operator. After 12 seconds if the ring detector output is low, it isensured that the phone has not been picked up by the operator. Themicrocontroller then switches the relay to the DTMF and sends a signal via RS232 to the pc to run the wave file welcoming the user to the IVRS. The user isalso informed of the various codes present in the system, which the user dial inorder to access the necessary information.Thirty seconds are given to the user to press the codes, failure ofwhich results in switch back of the relay. The DTMF decoder converts the codespressed by the user to BCD. It is then pressed to the input pins of themicrocontroller and is stored in the microcontroller memory. After these codeshave been received, they are transmitted serially to the serial port of the PC viamax232 IC. Any hardware failure in transmission falls in the lightning of a LEDand the relay is switched back.The serial port of the PC is continually polled by the software usedsuch as Visual Basics and Microsoft Agent program and the received code wordsare put in the text box from the input buffer. The received personal identificationnumber (PIN) is compared with the stored data base to determine the result. Thecorresponding wave file is played by the sound blaster card. It is coupled to thetelephone line through the Audio Amplifier, which is connected between thesound blaster and the telephone line to amplify the blaster output, drive thetelephone line acts as the buffer for sound blaster.
DIFFERENT PARTS OF IVRS
a) MICRO CONTROLLERTHE ROLE OF MICRO CONTROLLER
The 8751 is the heart of the IVRS system. It controls the operation ofvarious parts of the IVRS system. When a telephone call is detected by the ringdetector, the micro controller switches the relay to the DTMF and sends a signalto the PC via RS 232 to run the wave file welcoming the user to the IVRS. Thenumber given by the user is decoded by the DTMF IC and is stored in thememory of the microcontroller. The code stored in the microcontroller is send tothe serial port. If any hardware failure occurs, it is the microcontroller which istaking necessary measures. The IVRS system makes use of a stand by computerso as to working 24hrs a day for customer satisfaction. In these cases themicrocontroller switches from the first computer to the second.
THE BASIC FEATURES
A microcontroller is meant to read data, perform limited calculationson the data and control its environment based on those calculations. Themicrocontroller consists of an 8-bit CPU in addition to RAM of 128 bytes, ROM,parallel I/0, serial I/0, counters, clock circuits etc, the EEPROM has a memory of0 to 4kb. There are four register banks with 8 registers each. The control registersused are TCON, TMOD, SCON, PCON, IP and IE. The program counter is 16bit while the status word and stack pointer is 8 bit. The 8751 has 4 parallel I/0ports. Hence the dual ports of these may be used as general I/O digital lines.Asystem clock generator using an external crystal and two external capacitors provide the required clock for the microcontroller. There are 5 INTERRUPTsources used by 8751 and each can be listed under any of the priority levels. The5 interrupts are listed below.
b) RING DETECTOR
he ring detector is connected directly to the telephone line throughthe relay which is controlled by microcontroller (8751). The function of the ringdetector is to detect if the telephone is ringing or not.The ring detector consists of op-amp LM 311 which acts as acomparator to convert 98 V (rms, 130 Vpp) ring signal to –5V (low level) stepsignal for the microcontroller’s INTO pin. The output of the comparator goeshigh when the operator picks up the telephone provided along with the IVRS.The presence of the ring detector output for 5 sec enables the micro controller toswitch the relay to the dual tone multi frequency (DTMF 8870). The capacitorC1 blocks incoming DC and resistors RA and RB are the voltage dividers toreduce the incoming voltage of 13VPP to 15V. Diode D passes only the positive half of the sine wave during which C2 gets charged to maximum value and actsas the DC value for the input signal which triggers the comparator. This chargedoes not get discharged easily due to high resistance R3, R4 and R5 are used asvoltage dividers to provide reference voltage of 2.5V to pin 2 of LM 311.
