Designing of RF Secure Coded Communication System

RF secured communication systems have been approximately for several years with various applications. The technologies cover a large variety of capabilities oriented to different needs. These have been proceeding at an extraordinary rate, and their effect is clear in our daily lives. A smaller amount of wiring means better elasticity, efficiency, and reduced wiring costs. In several areas of the world, wireless communication is the best rising area of the communication industry, as long as a valuable supplement and substitute to existing wired networks. Based on the number of users, it is now the ideal technique of communication. A lot of systems in the past carried over the wire are now carried over wireless media.

Designing of RF Secure Coded Communication System

The hardware and software requirement of this RF secured communication system project includes 8051 series Microcontroller, RF Module, LCD, Computer keyboard, Resistors, Capacitors, Diodes, Transformer, Voltage Regulator, Push Buttons, Keil compiler, and Language: Embedded C or Assembly.

Block Diagram of Secret Code Enabled Secure Communication using RF Technology
Block Diagram of Secret Code Enabled Secure Communication using RF Technology

Power Supply

Please refer this link to know more about the classification of the power supply and its different types

Embedded Systems

An embedded system is a combination of hardware and software which together form a component of a larger machine. An example of an embedded system is a microprocessor that controls an automobile engine. An embedded system is designed to run on its own without human intervention and may be required to respond to events in real time.

AT89S52 Microcontroller

  • Compatible with MCS®-51 Products
  • 8K Bytes of In-System Programmable (ISP) Flash Memory
  • 4.0V to 5.5V Operating Range
  • Crystal Frequency 11.0592MHZ
  • Three-level Program Memory Lock
  • 256 x 8-bit Internal RAM
  • 32 Programmable I/O Lines
  • Three 16-bit Timer/Counters
  • Eight Interrupt Sources
  • Full Duplex UART Serial Channel
  • Watchdog Timer

LED – Light Emitting Diode

LEDs are semiconductor devices are made out of silicon. When current passes through the LED, it emits photons as a byproduct. Normal light bulbs produce light by heating a metal filament until its white-hot LEDs present many advantages over traditional light sources, including lower energy consumption, longer lifetime, improved robustness, smaller size and faster switching.

RF Remote Control

The circuit uses HT 12E, HT 12D encoder, and decoder. 433MHz ASK transmitter and receiver is used for the remote control.

  • Range in open space(Standard Conditions) : 100 Meters
  • RX Receiver Frequency: 433 MHz
  • RX Typical Sensitivity: 105 Dbm
  • RX Supply Current: 3.5 mA
  • RX IF Frequency: 1MHz
  • Low Power Consumption
  • Easy For Application
  • RX Operating Voltage: 5V
  • TX Frequency Range: 433.92 MHz
  • TX Supply Voltage: 3V ~ 6V
  • TX Out Put Power: 4 ~ 12 dBm

RF Encoder & Decoder

  • The HT 12E Encoder ICs are a series of CMOS LSIs for Remote Control system applications. They are capable of Encoding 12 bits of information which consists of N address bits and 12-N data bits.
  • The HT 12D ICs are a series of CMOS LSIs for remote control system applications.
  • These ICs are paired with each other. For proper operation, a pair of encoder/decoder with the same number of address and data format should be selected.
  • The Decoder receives the serial address and data from its corresponding decoder, transmitted by a carrier using an RF transmission medium and gives output to the output pins after processing the data.


Most common LCDs connected to the microcontrollers are 16×2 and 20×2 displays. This means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively. The standard is referred to as HD44780U, which refers to the controller chip which receives data from an external source (and communicates directly with the LCD.

Project Working RF Secure Coded Communication System

This project is intended to send safe messages with a secret code from a keyboard of PC which is connected to the transmitting (TX) unit through RF technology. The message is getting back at the receiver (RX) end only ahead entering the secret code used by the TX end. Therefore, total secrecy is preserved in this communication process.

Secret Code Enabled Secure Communication using RF Technology
Secret Code Enabled Secure Communication using RF Technology

For instance, in military operations, secrecy is one of the most important. So when there is a requirement of transmitting any secret code, one can enter the message through a PC keyboard which is interfaced to the system including of a microcontroller & an RF TX module.

This project has an exclusive feature of marking the message with a secret code as preferred by the sender. The note is then broadcasted through the RF TX module. At the RX end, the signal is received by the RF RX module. The message is then recovered only if the code is identified in the receiving persons. Once the code is entered, then a note is displayed on the RX unit on the LCD display.

Further, the proposed system can be improved by adding up a new feature of bidirectional communication and also add in encrypting & decrypting the message for a superior degree of security.

From the above information, finally, we can conclude that the text message is encrypted by using the Microcontroller and that is transmitted via wireless using RF transmitting Module. At the receiver end, the signal is received by the standard RF receiver and the analog signal is altered to digital form and is fed to the Microcontroller. It is decrypted by the microcontroller, and finally, the message will be displayed over the LCD. Here is a question for you, what are the applications of RF secure coded communication system?

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