ABSTRACT:

Everyone in this world wants to be safe and secure. Even a small kid tries to protect his toys in a safe place. The situation becomes more complicated when it comes to Multinational companies, Military, Army.

                   One of the popular methods to protect the data in a more secure way is to encrypt the data while sending and when received, decrypt the data to retrieve the original message. Before transmitting the data, the data will be converted into an unreadable form and will be sent. At the receiving end, the reverse of encryption carries on to get back the original message. Thus the data will be protected in every way by following the encryption and decryption standard formats. Wireless makes this project more flexible. Standard algorithms require software to be installed into the system before actually using them and hardwired connections. The hardware connections and cabling can be completely eliminated in this project.

  The RF communication technique is preferred here for it’s reliability and it can be used for long distance communication. The RF modules used here are STT-433 MHz Transmitter along with an RF encoder HT12E, STR-433 MHz Receiver along with an RF decoder HT12D. The project is designed in such a way that a PC will be interfaced to the controller through serial communication, using which we will input the data to the controller using the hyper terminal of PC. Here we will use a serial line driver IC MAX232   to interface the PC with controller. The RF transmitter is also interfaced to the controller through an RF encoder to encode the data received by the controller and to transmit the data. Hence the encoded data will be transmitted by the transmitter over the wireless medium and will be received by the RF receiver which will be interfaced to the controller through an RF decoder, on the receiver side. The RF decoder is used to decode the received data into a 4 bit digital data which will be fed to the controller. Now it is the responsibility of the controller to transfer the received data to the PC which will have interfaced to the controller, using serial communication. Hence a secured wireless data transfer can be achieved.

This project uses regulated 5V, 500mA power supply. Unregulated 12V DC is used for relay. 7805 three terminal voltage regulator is used for voltage regulation. Full wave bridge rectifier is used to rectify the ac output of secondary of 230/12V step down transformer.

TECHNICAL SPECIFICATIONS:

HARDWARE:

Micro controller         :           AT89S52

Crystal                        :           11.0592 MHz

RF transmitter             :           STT-433MHZ

RF receiver                 :           STT-433MHZ

RF encoder                 :           HT12E

RF decoder                 :           HT12D

PCS

Serial line driver IC    :           MAX232

Power supply

Transformer                :           12V step down 

Filter                           :           1000uf/25V

Voltage Regulator      :           7805

SOFTWARE :

Keil microvision

Proteus

 UC flash

APPLICATIONS:

• Industrial applications