08-05-2012, 12:55 PM
DESIGN AND DEVELOPMENT OF MICROCONTROLLER BASED WALKIE TALKIE SYSTEM
[attachment=21546]
INTRODUCTION
A walkie-talkie, or handy talkie, (more formally known as a handheld transceiver) is a hand-held, portable, two-way radio transceiver. It was developed during the Second World War. After the war, walkie-talkies spread to public safety and eventually commercial and jobsite work. Major characteristics include a half-duplex channel (only one radio transmits at a time, though any number can listen) and a "push-to-talk" (P.T.T) switch that starts transmission. Typical walkie-talkies resemble a telephone handset, possibly slightly larger but still a single unit, with an antenna sticking out of the top. Where a phone's earpiece is only loud enough to be heard by the user, a walkie-talkie's built-in speaker can be heard by the user and those in the user's immediate vicinity.
Walkie-talkies facilitate us to communicate with alternative individuals while not any restriction of place. We can keep in touch with other individuals even when we are at home, workplace or experiencing the adventure of hiking, mountaineering etc.
A good quality walkie-talkie has following features.
• Range about 3 miles
• Stop watch
• CTCSS & VOX
• eight to ten channels
• Channel scanner
• Auto power off facility
• Earpieces
• Completely different decision tones
• Charging cradle
• Some warlike-talkies even have baby monitor
Walkie-talkie provides us the communication school while not any price within the coverage area. Some walkie-talkies offer us facility of communicating with a lot of than one person at time.
Walkie-talkie radios are easy electronic devices. For communicating with these radios, we've got to line the channel or channels at a particular frequency. That’s all! We have got to just push a button when we're speaking and unharness the button when we're listening. This service is freed from cost and we need not to pay any rental.
Following are the main differences between a walkie-talkie and a mobile phone.
• Mobile phones need outside network for operation as signals are transmitted indirectly through network. You've got to pay for creating calls and even rental for using mobile phones.
• For using walkie-talkie radio you want to bear in mind to “push” and “unharness” the button for speaking and listening.
WORKING OF A SIMPLEX WALKIE TALKIE:
Frequency is the most important factor in the utilization of walkie-talkie. When the tuned frequency matches folks using walkie-talkie then they will communicate with each other. The communications signals received by the walkie-talkie are converted into radio waves and these radio waves reach the receiver. Once the radio waves reach the receiver, they're again converted into communication signals.
In order to transmit a signal we need to first sense the signal using a sensor for example voice signal is sensed using a mike, then filter the signal for any kind of noise or disturbance distorting the signal then we should amplify it for better transmission. This amplified signal is analog in nature so we need to convert it in digital form in order to make the transmission easy and fast. This conversion is done by using analog to digital convertors also known as ADC. The function of this ADC is controlled using a microcontroller. ADC interfacing takes place by programming the microcontroller. As microcontrollers are multifunctional they then send the digital data received from ADC to encoder. The encoder codes the digital data into binary bits and sends it to the transmitter which transmits these bits at a particular frequency in air using the antenna. So this is the process which takes place at the transmitter end.
While receiving the transmitted data at the other end by a receiver, a reverse process takes place which means that binary bits are first received by a receiver of same frequency as that of the transmitter. Then decoding of these binary bits take place using a decoder. The output of a decoder is the digital data which is then sent to microcontroller. The microcontroller is programmed to input this data and send it to the DAC (digital to analog convertor). Finally the transmitted analog signal is recovered through the DAC and sent to a power amplifier connect to it. This power amplifier amplifies the received analog signal so that it can be heard on a speaker. Thus transmitted signal is recovered n process of transmission is complete.
In this way a walkie talkie transmits and receives a voice signal in the simplest way.
ABOUT THE COMPANY
D.R.D.O
DRDO was formed in 1958 from the amalgamation of the then already functioning Technical Development Establishment (TDEs) of the Indian Army and the Directorate of Technical Development & Production (DTDP) with the Defence Science Organisation (DSO). DRDO was then a small rganization with 10 establishments or laboratories. Over the years, it has grown multi-directionally in terms of the variety of subject disciplines, number of laboratories, achievements and stature
Today, DRDO is a network of 51 laboratories which are deeply engaged in developing defence technologies covering various disciplines, like aeronautics, armaments, electronics, combat vehicles, engineering systems, instrumentation, missiles, advanced computing and simulation, special materials, naval systems, life sciences, training, information systems and agriculture. Presently, the Organisation is backed by over 5000 scientists and about 25,000 other scientific, technical and supporting personnel. Several major projects for the development of missiles, armaments, light combat aircrafts, radars, electronic warfare systems etc are on hand and significant achievements have already been made in several such technologies.
DRDO- Vision & Mission
VISION
Make India prosperous by establishing world class science and technology base and provide our Defence Services decisive edge by equipping them with internationally competitive systems and solutions.
MISSION
• Design, develop and lead to production state-of-the-art sensors, weapon systems, platforms and allied equipment for our Defence Services.
• Provide technological solutions to the Services to optimize combat effectiveness and to promote well-being of the troops.
• Develop infrastructure and committed quality manpower and build strong indigenous technology base.
CFEES (Centre for Fire, Explosives & Environment Safety)
The Centre for Explosive and Environment Safety (CEES) was established in 1992 by merging three DRDO establishments; DRDO Computer Centre, Delhi, The Directorate of Explosives Safety, DRDO HQ, and the Fire Adviser’s Office, DRDO HQ. In 2000 another DRDO lab, “Defence Institute of Fire Research (DIFR)” was merged with CEES. In order to emphasize the importance of Fire Science, the Government renamed CEES as CFEES in 2003.
[attachment=21546]
INTRODUCTION
A walkie-talkie, or handy talkie, (more formally known as a handheld transceiver) is a hand-held, portable, two-way radio transceiver. It was developed during the Second World War. After the war, walkie-talkies spread to public safety and eventually commercial and jobsite work. Major characteristics include a half-duplex channel (only one radio transmits at a time, though any number can listen) and a "push-to-talk" (P.T.T) switch that starts transmission. Typical walkie-talkies resemble a telephone handset, possibly slightly larger but still a single unit, with an antenna sticking out of the top. Where a phone's earpiece is only loud enough to be heard by the user, a walkie-talkie's built-in speaker can be heard by the user and those in the user's immediate vicinity.
Walkie-talkies facilitate us to communicate with alternative individuals while not any restriction of place. We can keep in touch with other individuals even when we are at home, workplace or experiencing the adventure of hiking, mountaineering etc.
A good quality walkie-talkie has following features.
• Range about 3 miles
• Stop watch
• CTCSS & VOX
• eight to ten channels
• Channel scanner
• Auto power off facility
• Earpieces
• Completely different decision tones
• Charging cradle
• Some warlike-talkies even have baby monitor
Walkie-talkie provides us the communication school while not any price within the coverage area. Some walkie-talkies offer us facility of communicating with a lot of than one person at time.
Walkie-talkie radios are easy electronic devices. For communicating with these radios, we've got to line the channel or channels at a particular frequency. That’s all! We have got to just push a button when we're speaking and unharness the button when we're listening. This service is freed from cost and we need not to pay any rental.
Following are the main differences between a walkie-talkie and a mobile phone.
• Mobile phones need outside network for operation as signals are transmitted indirectly through network. You've got to pay for creating calls and even rental for using mobile phones.
• For using walkie-talkie radio you want to bear in mind to “push” and “unharness” the button for speaking and listening.
WORKING OF A SIMPLEX WALKIE TALKIE:
Frequency is the most important factor in the utilization of walkie-talkie. When the tuned frequency matches folks using walkie-talkie then they will communicate with each other. The communications signals received by the walkie-talkie are converted into radio waves and these radio waves reach the receiver. Once the radio waves reach the receiver, they're again converted into communication signals.
In order to transmit a signal we need to first sense the signal using a sensor for example voice signal is sensed using a mike, then filter the signal for any kind of noise or disturbance distorting the signal then we should amplify it for better transmission. This amplified signal is analog in nature so we need to convert it in digital form in order to make the transmission easy and fast. This conversion is done by using analog to digital convertors also known as ADC. The function of this ADC is controlled using a microcontroller. ADC interfacing takes place by programming the microcontroller. As microcontrollers are multifunctional they then send the digital data received from ADC to encoder. The encoder codes the digital data into binary bits and sends it to the transmitter which transmits these bits at a particular frequency in air using the antenna. So this is the process which takes place at the transmitter end.
While receiving the transmitted data at the other end by a receiver, a reverse process takes place which means that binary bits are first received by a receiver of same frequency as that of the transmitter. Then decoding of these binary bits take place using a decoder. The output of a decoder is the digital data which is then sent to microcontroller. The microcontroller is programmed to input this data and send it to the DAC (digital to analog convertor). Finally the transmitted analog signal is recovered through the DAC and sent to a power amplifier connect to it. This power amplifier amplifies the received analog signal so that it can be heard on a speaker. Thus transmitted signal is recovered n process of transmission is complete.
In this way a walkie talkie transmits and receives a voice signal in the simplest way.
ABOUT THE COMPANY
D.R.D.O
DRDO was formed in 1958 from the amalgamation of the then already functioning Technical Development Establishment (TDEs) of the Indian Army and the Directorate of Technical Development & Production (DTDP) with the Defence Science Organisation (DSO). DRDO was then a small rganization with 10 establishments or laboratories. Over the years, it has grown multi-directionally in terms of the variety of subject disciplines, number of laboratories, achievements and stature
Today, DRDO is a network of 51 laboratories which are deeply engaged in developing defence technologies covering various disciplines, like aeronautics, armaments, electronics, combat vehicles, engineering systems, instrumentation, missiles, advanced computing and simulation, special materials, naval systems, life sciences, training, information systems and agriculture. Presently, the Organisation is backed by over 5000 scientists and about 25,000 other scientific, technical and supporting personnel. Several major projects for the development of missiles, armaments, light combat aircrafts, radars, electronic warfare systems etc are on hand and significant achievements have already been made in several such technologies.
DRDO- Vision & Mission
VISION
Make India prosperous by establishing world class science and technology base and provide our Defence Services decisive edge by equipping them with internationally competitive systems and solutions.
MISSION
• Design, develop and lead to production state-of-the-art sensors, weapon systems, platforms and allied equipment for our Defence Services.
• Provide technological solutions to the Services to optimize combat effectiveness and to promote well-being of the troops.
• Develop infrastructure and committed quality manpower and build strong indigenous technology base.
CFEES (Centre for Fire, Explosives & Environment Safety)
The Centre for Explosive and Environment Safety (CEES) was established in 1992 by merging three DRDO establishments; DRDO Computer Centre, Delhi, The Directorate of Explosives Safety, DRDO HQ, and the Fire Adviser’s Office, DRDO HQ. In 2000 another DRDO lab, “Defence Institute of Fire Research (DIFR)” was merged with CEES. In order to emphasize the importance of Fire Science, the Government renamed CEES as CFEES in 2003.