MORSE CODE BASED DIGITAL COMMUNICATION SYSTEM

Morse code is a method of transmitting messages over a long distance using two elements 'dit' (or 'dot' or short pulse in electronic term) and 'dah' (or 'dash' or long pulse in electronic term). All English alphabets and Numerals 0 to 9 can be coded using Morse code (see the picture below). It is just like coding in '0s' and '1s' in today's digital world.

Morse code was invented and put to use during mid of 19th century; however it is so robust & easy to understand & implement that it is used even today in some of the applications. The most important applications of Morse code was in Electrical telegraph system for sending telegrams during 19th century, it was extensively used for communication during World War I and II in 20th century and even today in 21st century it is used in Aviation, Navigation, Coast Guard, Amateur Radio Applications etc.

We have developed an electronic system called Morse Code Cracker as our academic project. We used an embedded processor and by using push buttons we generated the Morse code which is understood by the processor and processor decodes it and display a decoded message (alpha numeric) on LCD display. Before we give an overview of our project, let us see how original Morse code based communication system works – we call it a classical system.

Classical System

In 1836 Samuel F.B Morse an American artist along with his colleagues Joseph Henry (physicist), and Alfred Vail developed an electrical telegraph system using a principal of electromagnetic induction. They used a Straight Key to transmit the electric current correspond to dit and dah using electromagnet, and at the receiving end this current caused mechanical movement in another electromagnet at receiving end, the mechanical movement generated sound at receiving end and an operator at receiving end translated these sounds into dit and dah, thereby decoding the code.

Modern System – Electronic Communication System Using Morse Code

In electronic based system, semiconductor components are used to generate pulses for dit and dah. For example an oscillator or multivibrator (in astable mode) can be used to generate square wave pulses correspond to dit and dah. A switch is used to control a time period of pulses distinguishing dit from dah. For example for dit one unit of pulse is generated, for dah 3 units of pulse is generated. These pulses can be fed to any microcontroller or processor that converts them into digital bit steam. Digital date is transmitted wirelessly using RF or FM transmitter. At the receiver end RF or FM receiver receives the data and fed to another microcontroller for decoding. The decoded message is displayed on the LCD screen. In our project we have used a single microcontroller (ATMEGA328 from ATMEL) for encoding and decoding Morse code, we have not built the transmission channel, hence the project is called Morse Code Cracker. Future scope of our project is to build full fledge Morse code based communication system.

There can be another kind of signal that can be used for morse code based communication system - Light Signal. But the limitation is that this communication is line of sight. Such system is used by coast guard or navy in some applications as a manual communication system, where a person transmitting morse code using light understands the c ode well and person at receiving end should be able to decode the code manual by looking at the light pulses being transmitted.

By-Pratyaksh Joshi (1411981523), Jeetshu Majumder (1411981602) - Students ECE 2nd year
and Sagar Juneja - Research Associate Chitkara University