Morse code is named in honor of Samuel F.B. Morse, an American who invented the telegraphic code. The morse code basically consists of two elements, the dot (.), called "dit", which is the shortest element, also called unit element and the lash (-), called "dah", which is the longer element. The dot is about one-fourth the duration of a second. The dash is three times longer than the dot. The relative durations of dots, dashes and other elements have been fixed by international agreement. Thus:
A dot length = l/4th of a second.
A dash length = 3 dots length.
Spacing between elements of a character = 1 dot length.
Spacing between character of a word = 3 dots length.
Spacing between the words = 7 dots length.
The International Morse Codes for alphabets and numerals are given in table
Morse code Telegraph System
The morse code telegraph system is a simple electric circuit consisting of the following components:
- A battery:
which acts as a source of electrical energy in the circuit.
- Morse key:
It is a manual key and acts as a switch to open and close the circuit. Thus causing pulses of current to flow on the line. When the operator starts opening and closing of the key. The transmission of information and encoding starts at the same time
- Transmission line:
Acts a medium for the transmission information between the two stations. The dots and dashes flow-on the line in the form of electrical energy and are carried instantly through the wires from the transmitter to the receiver.
The receiver used is called a sounder, because it produces click like sound. The receiver consists of electromagnet and a movable armature. When a pulse of current passes through the electromagnet, it attracts the armature and click is produced. When the pulsed stops, the armature returns to its normal position with the help of a spring and again makes a click. The time between the clicks represents a dot or a dash. These clicks are heard by an operator and are decoded into messages in the written form by him.
The morse code telegraph system is illustrated in the figure.
Single and Double Current Morse code System
The morse code system may be either single current or double current. In the single current system single battery is used. The current on the line flows only in one direction. There is current on the line when dot or dash is transmitted and no current when neither dot nor dash is transmitted. The advantage of single current system is low power consumption. However, the flow of current is slower and thus is a disadvantage.
In the double current system two batteries of opposite polarities are used. There is always current on the line, which may be either positive or negative. For dot or dash the current on the line is positive while for space it is negative. The double current system is more sensitive and speedier than the single current system.