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Security System Using Gsm And Pir Sensors Information Technology Essay

Paper Type: Free Essay Subject: Information Technology
Wordcount: 3174 words Published: 1st Jan 2015

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The security system using PIR sensors uses pyroelectric infrared transducer, pyroelectic infrared detector circuit, PIC(peripheral interface connector) microcontroller, power supply unit, buzzer, UART, GSM modem, flash memory.

This is the block diagram of this project. It has a power supply unit on its top which supplies power to the microcontroller. The heat signals enter the pyroelectric infrared transducer and it is passed through the pyroelectric infrared detector circuit. Then the signals are passed through the microcontroller. The microcontroller used here is the PIC 16F877A. There is also a flash programmed memory. The UART(Universal Asynchronous Receiver Transmitter) is connected to the GSM Modem. A buzzer is fitted to alert the security personals.

Pyroelectric infrared transducer:

The pyroelectric infrared transducer performs the function of transmission and receiving the signals. The signals which pass through the transducer are the infrared heat signals. It has the Fresnel lens which performs the function of converging the infrared signals and passing it to the infrared sensor.

Pyroelectric infrared sensor module:

The PIR sensors are compact and easy to use. It has a special property of detecting human heat which is generated from the body and thus detects human movement. It consumes low power and it has quite a lot of properties in which it has a transmitter and receiver in itself therefore there is no need for point to point communication. It is 28mm Length, 38mm Width, 40mm Height and hence it is so compact.

Power supply unit:

The features of power supply unit are

Output Current up to 1A

Output Voltages of 5 to 24

Thermal Overload Protection

Short Circuit Protection

Output Transistor Safe Operating Area Protection

The power supply unit provides current up to 1 amperes. It can also used to produce voltages of 5 to 24. It protects the circuit from thermal overload and other short circuit problems. The “78xx” series (7805, 7812, etc.) regulate positive voltages while the “79xx” series (7905, 7912, etc.) regulate negative voltages.

In this circuit the signal is down converted to smaller peak voltage using a transformer. The input signal is in the form of AC and hence it is down converted. The converted signal is then passed on to the rectifier circuit which rectifies the signal. The rectifier used here is the bridge rectifier circuit. The rectified signal is then passed into the filter. The filter used is the capacitor filter which filters and obtains a smooth signal. The processed signal is then passed into the regulator which regulates the processed signal. The residual periodic variation or ripple in this filtered signal is eliminated using an active regulator.

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Circuit features:

The circuit gives a well regulated output and it protects the circuit from overheating problems. The circuit is not complex and it is easy to build. The performance of the circuit is quite noticeable because it gives a stable output. The circuit components are readily available and it is very common. The supply voltage is also very less and it is affordable also. These are the features of this circuit.

Pyroelectric infrared sensors:

The pyroelectric infrared sensors are the widely used infrared sensor at the current times. It responds to the heat from the humans and detects the heat which is associated with the motion. Nowadays these sensors are widely used in most of the security systems.

PIR Sensor Module

This sensor is compact and more reliable than other sensors. It has the Fresnel lens in it and it detects the human motion by detecting the heat from the body. It consumes very low power and its highly reliable and hence most of the housing systems for security purposes uses this sensor. The output is the standard TTL output and hence it is more efficient. There is a dual element pyroelectric detector for detecting the heat. It has high sensitivity and highly reliable and has low noise. It is mainly used for motion detecting purposes. The adjustable delay time is 5 seconds to 18 minutes. The supply voltage required for this sensor is 5-20vdc. It is 28mm in length, 38mm in width and 40mm in height and hence it is more compact.

Lens information

The sensor can detect human heat 140 degree wide and upto 5-7m straight and 3-4m wide and hence it is more effective. This lens is not advised to use in direct sunlight and in rapid environmental change places. Since the IR cannot pass through obstructing materials like glass, it is not recommended to use in places where there are such kind of obstructing mediums.


The microcontroller is used because it has the CPU, RAM, ROM, I/O timer everything inside the same chip and hence it is widely used. It is designed for a single purpose. It is widely used in applications where cost, space and power are critical. In this project a PIC microcontroller is used.

PIC Microcontroller:

The PIC(Peripheral Interface Controller) is used to control the peripheral devices connected to the load. The PIC like the CPU is controlled by the software. It has its own functions and memory and is controlled by the software for it. The memory capacity of this microcontroller is 1K to 4K words depending on the kind of microcontroller. The instruction is executed from the memory and the clock frequency determines the speed at which the program is held. The maximum clock frequency is about 20Mhz. The microcontroller can do many jobs of an IC and hence it avoids so many IC’s into the circuit and hence maked the circuit more simple and compact. The PIC microcontroller is made by microchip technology and it is widely used now.

This is the picture of the PIC microcontroller and in this project PIC 16F877A is used. In this project we use this microcontroller because it is a high performance RISC CPU. The operating speed is 20 Mhz. There are 15 interrupt resources and 35 single word instructions

Peripheral features:

There are 33 I/O pins and 5 I/O ports. It has a synchronous serial port with two nodes. They are SPI master and 12C master and slave. It also has a PSP(parallel slave port).

This is the pin diagram of the PIC 16F874A.

We use PIC microcontroller because of its high performance and there are only 35 single word instructions to learn. It has a good memory unit. The memory unit in it is classified into FLASH program memory, data memory and EEPROM memory. It can store upto 8k x 14 words of flash programmed memory , upto 368 x 8 bytes of Data memory i.e)RAM and upto 256 x 8 bytes of EEPROM data memory. It also have a high speed CMOS technology. It is a fully static design and consumes very less power. The each memory block has their own buses. The data memory unit has many special purpose registers and other general purpose registers. These general purpose registers can be accessed directly or indirectly by File Selection Registers(FSR). The special purpose registers are used by the CPU to access and control the device.

Pin description

The OSC1/CLK1represents the crystal oscillator or clock input. The OSC2/CLK0 represents the crystal oscillator or clock output. The MCLR represents the master clear input, VSS represents the ground reference for logic and input output pins, VDD represents the positive supply for positive supply for logic and input output pins. The PIC has five input/output ports from Port A to Port E.


If you are using mobile phones you would have probably heard of GSM which is Global system for mobile communications.

It is the cellular system which is developed to transmit data and voice. It is dev eloped in the early 1970’s in the BELL laboratories. The GSM is the name of a standard group which is developed to create a common European standard. The GSM standard is widely accepted by all and it is implemented globally. Almost all of the world nations now follow the GSM standard. The GSM is designed based in the circuit switched system which divides 200 KHz into eight 25 KHZ time slots. The GSM captures 70% of the worlds cellular subscribers. The GSM transmit signals using narrowband time division multiple access(TDMA) . It also has the ability to provide roaming services to almost all parts of the country. Roaming is the service in which your GSM phone number will use in another GSM network. The GSM compress and digitize the data and then sends the data through a channel which has separate time slots.


The GSM provides good and efficient spectrum efficiency. It can also provide low cost mobile handsets with international roaming facility. Also setting up the base station for GSM based mobile is cheap. The call quality is also good and it is compatible with Integrated Services Digital Network (ISDN). It also supports new services.


A GSM network can be divided into

Mobile station

Base station

Network switching station

The operation support subsystem

simple architecture diagram

Fig. 5.1 GSM Architecture

Following is the diagram of GSM Network along with added elements. It is shown in Fig. 5.2


GSM network areas:

In a GSM network there is a basic area for all types of services. Each cell is identified with Global Identity number which is the number that uniquely identifies the cell. The group of cells are called as location area. The location area varies based on the locality of the mobile. When a user gets a call this area is coded. The location area is assigned a Location Area Identity (LAI) and it is served by many base stations.

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Modulation is the process of changing the input information to the format which suits the transmitting medium. Without modulation the signals cannot be transmitted since the transmitting medium can’t understand the type of input. Hence the modulation process is a important part in the GSM network. The signal is modulated in the transmitting side and it is demodulated in the receiving end. The GSM uses GMSK i.e. Gaussian Minimum Shift Keying method. One of the most important system in the GSM network is the International Mobile Station Equipment Identity (IMEI). It uniquely deyects and identifies the mobile station which is set up by the providers. It is actually a serial number with which the service providers will identify the network and the GSM device. The number is allocated by the GSM device provider with which the device can be located. It is registered by the network provider and the network operator stores this number. By this number one can identify if the device is stolen or missed.

International Mobile Subscriber Identity (IMSI):

All the registered users are identified by this International Mobie Subscriber Identity. This number is stored in the subscriber identity module (SIM). An operator can provide service only when this SIM is valid and it is in use. A base station can be operated with the information from the SIM and this should be inserted into the GSM device and hence a base station can identify your network.


It offers Telephony services in which the service is used to transport the data and other information’s. the most important service is the voice call service which includes the full rated speech and also offers emergency calls to the nearest emergency service provider which is of three digits.

Also it offers videotext which is an alternative to the speech. The other most important service which is used widely by all is the short text messages (SMS) which allows you to send and receive texts in the mobile device. This service is available in almost in every part of the world and it offers international text messages also and hence it is most important feature of the GSM service. The SMS can be from the service provider also to convey the message and also there are user generated text messages also which is created by the users. The other services include conference facility in which many users can interact through voice calls at the same time. The next feature is the call waiting which offers if the user is busy with the other call. The call forwarding feature is the feature in which the calls can be forwarded to the given number which is provided by the user in case if there is no network coverage or if the device I turned off. It also offers caller ID feature which identifies the calling number from which malicious calls can be traced out.



The GSM modem is a wireless modem which is designed to work with the GSM network. It works with the set of AT commands. With this command a user can read, write, send, and delete the SMS messages. It also controls and monitors the signal strength and charging level of the battery. It works like a dial up modem. The only difference between the dial p modem and the GSM modem is the dial up modem works with the help of a telephone line whereas the wireless modem works with the help of the radio waves. This is the only difference between these two types of modem. The GSM modem is a external device such a PC card. It can be directly fixed to the laptop or the computer through a cable connecting them. It is like a GSM mobile. Like the GSM mobile which needs SIM card for its process the GSM modem also needs SIM card for its process since it works in the GSM technology. The set of commands which is used to control the modems is the AT commands. The GSM modem is a plug and play device which is a useful device for the single users since it supports all forms of GSM technologies. It is a Triband GSM modem and it has a build in TCP protocols and AT based commands. It requires a very less input voltage of 9V to 12V and the temperature ranges from -20 to +55 degree Celsius.


A buzzer is a electronic device which is very small in size which is used for household security purposes and also in automobiles as a signaling device. It is also used in household accessories like microwave oven etc.

It consists of number of sensors in which its gets active when the preset time is crossed or the sensors gets active. It gives a continuous or intermittent buzzing sound. At the early stages before decades it is used as an alternative to the metal gong which is used as a ringing noise. It is based on the electromechanical system which is anchored in the wall. And nowadays it is used in almost all of the electronic devices and in security system to alert the personals. And nowadays these ordinary buzzers are replaced with piezoelectric sounders which gives a high pitched sound than this.

The above diagram shows the picture of the buzzer which is so compact in size. The word buzzer came from the buzzing noise produced by the electromechanical devices. It turns active and starts giving buzzing sound when the signal gets buzzes in which is activated by the sensors present in it. The operating voltage is very less to make it functional and hence it requires a low input voltage from 3V to 20V. it can give a pressured sound level up to 73db and it is capable of producing a continuous beep sound unless the user turns it down. Hence it is widely used in all types of security systems and in household items. It is also very compact in size and its weight is less than 5 grams. It is also available widely and it is very cheap in the market.


The UART(Universal Asynchronous Receiver Transmitter) is an integrated circuit for performing communications between the microcontrollers and the PC’s.As shown in the block diagram the UART is the signal which connects both the PIC microcontroller and the GSM modem. It form the base of the connectivity of the GSM modem. the transmitted bits are being converted here and hence it perform the main function of bits being transmitted. It is done by the shift registers which are present with the UART and hence the transmission is a asynchronous transmission which allows the data to be transmitted without the need for the sender to send the clock signal. In this we used the asynchronous transmission but usually synchronous transmissions are preferred as it is more efficient than the asynchronous transmissions.


The heart of the transmitter is the TSR register. The data is stored in this register. Above the TSR register is the TXREG in which the shift register obtains the data from it. This consists of data in software. Once this register gets transferred its data to the TSR register it gets empty and it is again loaded with data. And now the flag bit can be set. This can be interrupted by the interrupt mode which is attached to it. The TSR register gets loaded again as soon as the stop bit is executed. First the SPBRG register is initialized to the baud rate. For the data to be loaded and gets transmitted enable the asynchronous serial port and if the interrupts are desired then set enable and if n bit transmission is selected the nth bit should be loaded in TXnD and then load the data for the transmission.


The data is received in the pin and it is drove towards data recovery block. The heart of the receiver is the RSR which is the receive shift register. When the stop bit is sampled the RSR register transfers data into the RCREG register


Nowadays, the installation of an affordable security system is a must in the urban cities as there are number of crimes has increased in the cities. This project involves security system using PIR and also through air by frequency modulation techniques involving GSM modem. Objects generate heat and also infra red radiation and those infrared radiations are varying between objects. For example the heat generated from human beings is different from those of animals. In such a ways the motion is detected using PIR sensors and also the information about the intruder is transmitted to the personnel using the GSM technology and hence it not only alerts the personnel by the buzzer provided but also it sends a message to the personnel to their GSM mobile and hence it gives a good security.

Keywords: Infrared sensors, ultraviolet rays, ultrasound, Microcontroller, GSM, SMS

IEEE Reference:

“Pyroelectric infrared sensor for intruder detection”Moghavvemi, M.   Lu Chin Seng  Dept. of Electronics. & Telecommunication. Eng., Malaya Univ., Malaysia

Seigmund M. Redl, Matthias K. Weber, Malcolm W.Oliphant “An Introduction to GSM”.

Feiedhelm Hillebrand, “GSM and UMTS, The creation og Global Mobile communications”


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