As we all know that state electricity board is facing tremendous problem of power generation & distribution. Load shedding is the only way which electricity board has sought the problem for satisfying & fulfilling the needs of the consumers. Here Voice Guided Intelligent Telecontroller (VGIT) can be used for economic load dispatching schedule & connecting & disconnecting the consumers according to the maximum demand & billing status. VGIT is a device which when connected in parallel with the telephone line the operator can use the device for turning on & off the instrument even though he is sitting at far station by using DTMF signals of telephonic lines. It is also used in switching home appliances & agro pumps while showing us the present status of the appliance & also preventing illegal operation. In industrial automation it is also used during emergencies & sterile places where it is not possible to reach. In such a way VGIT can be widely used in energy conservation, saving valuable time & protecting system stability
*We are ready with the Demo Model of Voice Guided Intelligent Telecontrol Switch *
INTRODUCTION
We would like to present a paper, which can be used to control any appliance connected to the electrical mains through the telephone line.
The system also plays an important role in energy as well as time saving. Also at places in industries where it is not possible for man to enter, this system can solve the problem. Switching of instrument at sterile places is possible through this working system, thus using the communication line an individual can operate the instrument at home or in industry of his interest. So, basically it can be called as a remote control, which also prevents the illegal use of the appliances. This is incorporated by means of an automatic reset feature, which in turn is accomplished by the time delay produced due to the micro-controller. This system is developed in such a manner that it does not disturb the normal operations of the appliances. When the unit is off the appliance can be operated normally i.e. using switches.
This system also provides the CALLER ID facility along with the
VOICE RECODING.
So basically the switch can be called a “REMOTE CONTROL” which also prevents the illegal use implemented through micro controllers based authorization check, integrating its computing abilities.
WHAT IS TELECONTROL SWITCH?
When connecting telecontrol switch with telephone lines, it can handle incomming as well as outgoing calls and then performs following processing features:
- DTMF or pulse tone input
- Creates off-hook after certain rings
- Checks the password and asks for device selection number
- Gives the selected device status
- Modifies the device status according to the user
- It also provides pre-recorded voice message.
GENERAL DESCRIPTION ABOUT TELEPHONY
Any telephone set will always be in any of the conditions mentioned below:
ON-HOOK:
It is the state whenever telephone handset is placed on the cradle. During this state, the telephone line is open circuit with the exchange and the voltage of –48V is available on each telephone line from the exchange.
OFF-HOOK:
This is the state whenever telephone handset is displaced from the cradle. During this state the voltage level is between +/-5V to +/-12V. The telephone OFF-HOOK resistance is typically 600ohm.
SIGNALING TONES
DIAL TONE:
This tone indicates that the exchange is ready to accept dialed digits from the subscriber. The subscriber should start dialing only after hearing the dial tone. Otherwise, initial dialed pulse may be missed by the exchange that may result in the call landing on wrong number. The dialed tone is 33Hz or 50Hz or 400Hz continuous tones.
RING TONE:
When the called party is obtained, the exchange sense out the ringing current to the telephone set of the called party. This ringing current has the familiar double ring pattern. Simultaneously, the exchange sends out the ringing tone to the calling subscriber, which has the pattern similar to that of ringing current, the two rings in the double ring pattern are separated by a time gap of 0.2sec and two double rings patterns by a time gap of 2sec. The burst has duration of 0.4sec. the frequency of the ringing tone is 133Hz or 400Hz.
BUSY TONE:
Busy tone is bursty 400Hz signal with silence period in between. The burst and silence duration has the same value of 0.75sec. A busy tone is sent out to the calling subscriber whenever the switching equipment or junction line is not available to put through the call or called subscriber line is engaged.
NUMBER UNOBTAINABLE TONE:
The number unobtainable tone is a continuous 400Hz signal. This tone may be sent to the calling subscriber due to a variety of reasons. In some exchanges this tone is 400Hz intermittent with 2.5sec ON period and 0.5sec OFF period.
ROUTING TONE:
The routing tone or call – in – progress tone is 400Hz or 800Hz intermittent patterns. In an electromechanical system it is usually 800Hz with 50% duty ratio and 0.5sec ON-OFF period. In analog electronic exchange it is 400Hz pattern with 0.5sec ON period and 0.5sec OFF period. In digital exchange it has 0.1sec ON-OFF period at 400Hz.
TOUCH – TONE KEY PAD
BLOCK DIAGRAM DESCRIPTION
DTMF DETECTOR MT8870:
The MT8870D/MT8870D-1 is a complete DTMF receiver integrating both the band split filter and digital decoder functions. The filter section uses switched capacitor tech-niques for high and low group filters; the decoder uses digital counting techniques to detect and decode all 16 DTMF tone-pairs into a 4-bit code. External component count is minimized by on chip provision of a differential input amplifier, clock oscillator and latched three-state bus interface.
FEATURES:
• Complete DTMF Receiver
• Low power consumption
• Internal gain setting amplifier
• Adjustable guard time
• Central office quality
• Power-down mode
• Inhibit mode
• Backward compatible with
MT8870C/MT8870C-1 MICROCONTROLLER AT89C51:
FEATURES:
• Compatible with MCS-51 ™ Products
• 4K Bytes of In-System Reprogrammable Flash Memory
– Endurance: 1,000 Write/Erase Cycles
• Fully Static Operation: 0 Hz to 24 MHz
• Three-level Program Memory Lock
• 128 x 8-bit Internal RAM
• 32 Programmable I/O Lines
• Two 16-bit Timer/Counters
• Six Interrupt Sources
• Programmable Serial Channel
• Low-power Idle and Power-down Modes
BLOCK DIAGRAM OF 89C51
The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set and pinout.
VOICE RECODER:
FEATURES :
• Single-chip, high-quality voice recording & playback solution
- No external ICs required
- Minimum external components
• Non-volatile Flash memory technology
- No battery backup required
• User-Selectable messaging options
- Random access of multiple fixed-duration messages
- Sequential access of multiple variable-duration messages
• User-friendly, easy-to-use operation
- Programming & development systems not required
- Level-activated recording & edge-activated play back switches
• Low power consumption
- Operating current: 25 mA typical
- Standby current: 1 uA typical
- Automatic power-down
• Chip Enable pin for simple message expansion
The APR9600 device offers true single-chip voice recording, non- volatile storage, and playback capability for 40 to 60 seconds. The device supports both random and sequential access of multiple messages. Sample rates are user-select-able, allowing designers to customize their design for unique quality and storage time needs. Integrated output amplifier, microphone amplifier, and AGC circuits greatly simplify system design. the device is ideal for use in portable voice recorders, toys, and many other consumer and industrial applications. APLUS integrated achieves these high
levels of storage capability by using its proprietary analog/multilevel storage technology implemented in an advanc-ed Flash non-volatile memory process, where each memory cell can store 256 voltage levels. This technology enables the APR9600 device to reproduce voice signals in their natural form. It eliminates the need for encoding and compression, which often introduce distortion.
ALPHANUMERIC DOT MATRIX MODULES:
FEATURES:
• Low power consumption.
• Low threshold voltage
• Uniform brightness with good contrast
• Low operating voltage and current
• Low cost.
Over her we are using 2 line, 16 bit, 5x7 dot matrix liquid crystal display. The liquid crystals are one of the most fascinating material systems in nature, having properties of liquid and solid crystal. The term liquid crystal refers to the fact that these compounds have a crystalline arrangement of modules, yet they flow like a liquid. Liquid crystal displays do not emit or generate light, but rather alter externally generated illumination. Their ability to module light when electrical signal is applied has made them very useful in flat panel display technology.
There are mainly two types of LCDs according to the theory of operation:
1) Dynamic scattering LCDs.
2) Field effect display.
OPTOCOUPLER:
Optocoupler used here is MCT-2E. The optocoupler is a device that provide complete electrical isolation between input circuit and output circuit. If It is simply a package that contains both light emitter such as infrared LED and light sensor such as phototransistor linked only by a beam of light. The purpose of such isolation is to provide protection from high-voltage transients, surge voltage, or low-level noise that could possibly result in an erroneous output or damage to the device. These devices also allow us to interface circuits with different voltage and different grounds.
RELAY DRIVER:
FEATURES:
• 500-mA rated collector current (single output)
• High-voltage outputs…50V
• Output clamp diodes
• Inputs compatible with various types of logic
• Relay driver applications`
Here we are using ULN2003 relay driver IC (open collector darlington pair inverter IC) and the output of the driver IC is connected to the relay. It is a
7-bit, 50V, 500mA, TTL-inputs, NPN Darlington driver, the drivers need no power supply. The Vcc pin is common cathode of the 7 integrated protection diodes. Optocoupler ULN2003 increases the driving capacity of the outputs.
POWER SUPPLY:
An ideal regulated power supply is an electronic circuit designed to provide a predetermined voltage Vo, which is independent of load current, temperature and also of any variations in line voltage.
This system basically is a switch which is connected in parallel to the telephone line. When the system is switched ON, it switches OFF all the output devices and displays the messages on the display.
MCT2E is an optocoupler which detects the incoming ring. The anode of the optodiode is connected to the telephone line via a 10K resistor & 2.2µf bipolar capacitor. When the ring (75mV, 25Hz) arrives there is a voltage drop across the photodiode and the output of the collector ( pulled up by 10K resistor goes low). This is fed to port-1.4 of 89c51, so that the microcontroller knows that there is a incoming ring. After 5 rings (as programmed) microcontroller switches ON relay-1. This indicates that an OFF-HOOK condition is created and the telephone loop is established via telephone matching coil (T1). Impedance of telephone coil is 600Ω.
Telephone line is connected to pin no 1 & 2 of 8870 via 100K current limiting resistor and 0.1µf capacitor. 8870 is a widely used DTMF decoder in industries. Steering circuit is connected between pin no 16 & 17 of 8870. Steering circuit works in reverse to validate the interdigit pause between signals. The DTMF decoder uses digital counting technique to detect and decode all 16 DTMF tone pairs into 4 - bit code. This 4 - bit code is available at pin no 11, 12, 13 &14 of 8870 which is then connected to port 1 of 89c51 (P1.0-P1.3). 8870 gives STD (delay steering output flag)high signal at pin no
15. This indicates that valid DTMF tone is received and data is converted into BCD and is available for further process. STD signal is given to pin no 12 of 89c51 through a transistor (T1) which acts as a inverter and has a 10K pull up resistor connected to the collector. Thus T1 makes STD signal low and is given to INTO (P3.2) of 89c51. Thus microcontroller is interrupted. It reads data from port 1. The received data is then converted to ASCII and sent to LCD. Same time 89c51 stores data and accordingly it sends signals to pin no 10, 11, 13, 14, 15, 16 to voice recorder APR 9600 pin no 1-6. These signals are low triggered signals.
LCD is connected to 89c51 through pin 4, 5, 6. When ring arrives at 89c51 LCD will display the incoming number through the data coming from data bus connected to port 0 of 89c51. After 89c51 detects five rings relay 1 is made ON and it sets the timer for 10 sec and takes the received dialled digits stored by instruction routine of 89c51. Then it compares the dialled password and if the password is valid APR asks for the device number otherwise relay 1 will be switched OFF. The system checks whether the entered device number is valid or not. If valid it checks the status of the device and accordingly APR plays the message that the device is ON/OFF and if it is not valid then it again asks to enter the device number. The user can change the status of the device if required by dialling 1/0. If the user dials ‘1’ the system makes the device ON and if the user dials ‘0’ the system make the device OFF and accordingly APR plays the messages that the device is turned ON/OFF.
The port2 pins of 89c51 are connected to ULN2003 relay driver IC (open collector darlington pair inverter IC) and the output of the driver IC is connected to the relay. Resistors (R1-R6) of 10K connected between input terminals of relay driver IC and output pins of microcontroller acts as current limiting resistors. Appliances are being operated through these relays.
APPLICATIONS
1. In industries, it is possible for a person to sit in his cabin and operate the machinery through a communication line with the help of our system.
2. Controlling of an instrument at sterile places where it is not possible for a person to enter can be done through our system.
3. It has a wide application in offices and homes in regulating different electrical appliances for e.g. computer, air conditioners, motors etc.
4. It is basically used a remote access system or a remote control, which prevents illegal use of the equipments.
5. It can operate the economic load dispatch schedule, so as to improve our power system stability.
LIMITATIONS
1. This system can work only on DTMF facility and not pulse dialing.
2. Only 6 appliances can be interfaced to the system due to the limitations of port pins available.
3. Only six messages can be pre-recorded by APR due to the limitations of port pins available.
4. This system can work only on dual telephone line and not on multi- telephone line.
5. This system can make the appliance ON/OFF, but it does not provide an intermediate state.
CONCLUSION
Voice Guided Intelligent Telecontrol Switch makes life easy & tensionless as it provides highest security with saving tremendous time & money. VGIT is very economical with easy handling & installation, saving energy & bringing Power System Stability.
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nice. Good info
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