MORSE CODE

Scout Whistle

Morse Code is a type of character encoding that transmits telegraphic information using rhythm. Morse Code uses a standardized sequence of short and long elements to represent the letters, numerals, punctuation and special characters of a given message. The short and long elements can be formed by sounds, marks, or pulses, in on off keying and are commonly known as "dots" and "dashes" or "dits" and "dahs". The speed of Morse Code is measured in words per minute (WPM) or characters per minute, while fixed-length data forms of telecommunication transmission are usually measured in baud or bps.

Originally created for Samuel F. B. Morse's electric telegraph in the early 1840s, Morse Code was also extensively used for early radio communication beginning in the 1890s. For the first half of the twentieth century, the majority of high-speed international communication was conducted in Morse Code, using telegraph lines, undersea cables, and radio circuits. However, the variable length of the Morse characters made it hard to adapt to automated circuits, so for most electronic communication it has been replaced by machine readable formats, such as Baudot code and ASCII.

The most popular current use of Morse Code is by amateur radio operators, although it is no longer a requirement for amateur licensing in many countries. In the professional field, pilots and air traffic controllers are usually familiar with Morse Code and require a basic understanding. Navigational aids in the field of aviation, such as VORs and NDBs, constantly transmit their identity in Morse Code. Morse Code is designed to be read by humans without a decoding device, making it useful for sending automated digital data in voice channels. For emergency signaling, Morse Code can be sent by way of improvised sources that can be easily "keyed" on and off, making Morse Code one of the most versatile methods of telecommunication in existence.

History and Development

Beginning in 1836, Samuel F. B. Morse and Alfred Vail developed an electric telegraph, which sent pulses of electrical current to control an electromagnet that was located at the receiving end of the telegraph wire. The technology available at the time made it impossible to print characters in a readable form, so the inventors had to devise an alternate means of communication. In 1837, William Cooke and Charles Wheatstone began operating electric telegraphs in England that also had electromagnets in the receivers; however, their systems used needle pointers that rotated to indicate the alphabetic characters being sent.

In contrast, Morse's and Vail's initial telegraph, which first went into operation in 1844, made indentations on a paper tape when an electrical current was transmitted. Morse's original telegraph receiver used a mechanical clockwork to move a paper tape. When an electrical current was received, an electromagnet engaged an armature that pushed a stylus onto the moving paper tape, making an indentation on the tape. When the current was interrupted, the electromagnet retracted the stylus, and that portion of the moving tape remained unmarked.

The Morse code was developed so that operators could translate the indentations marked on the paper tape into text messages. In his earliest code, Morse had planned to only transmit numerals, and use a dictionary to look up each word according to the number which had been sent. However, the code was soon expanded by Alfred Vail to include letters and special characters, so it could be used more generally. The shorter marks were called "dots", and the longer ones "dashes" and the letters most commonly used in the English language were assigned the shortest sequences.

In the original Morse telegraphs, the receiver's armature made a clicking noise as it moved into and out of position to mark the tape. Operators soon learned to translate the clicks directly into dots and dashes, making it unnecessary to use the paper tape. When Morse code was adapted to radio, the dots and dashes were sent as short and long pulses. It was later found that people become more proficient at receiving Morse code when it is taught as a language that is heard, instead of one read from a page. To reflect the sound of Morse code, practitioners began to vocalise a dot as "dit" and a dash as "dah".

Morse code was an integral part of international aviation. Commercial and military pilots were required to be familiar with it, both for use with early communications systems and identification of navigational beacons which transmitted continuous three letter ID's in Morse code. As late as the 1990s, aeronautical charts listed the three letter ID of each airport in Morse and sectional charts still show the Morse signals for Vortac and NDB used for in flight navigation.

Morse code was also used as an international standard for maritime communication until 1999, when it was replaced by the Global Maritime Distress Safety System. When the French navy ceased using Morse code in 1997, the final message transmitted was "Calling all. This is our last cry before our eternal silence."

Dùng Morse trong sinh hoạt Phong Trào

Morse Code Alphabet

A
• ―
B
― • • •
C
― • ― •
D
― • •
E
F
• • ― •
G
― ― •
H
• • • •
I
• •
J
• ― ― ―
K
― • ―
L
• ― • •
M
― ―
N
― •
O
― ― ―
P
• ― ― •
Q
― ― • ―
R
• ― •
S
• • •
T
U
• • ―
  V
• • • ―
W
• ― ―
X
― • • ―
Y
― • ― ―
Z
― ― • •
 

Morse Code Numbers

  1
• ― ― ― ―
2
• • ― ― ―
3
• • • ― ―
4
• • • • ―
5
• • • • •
 
  6
― • • • •
7
― ― • • •
8
― ― ― • •
9
― ― ― ― •
0
― ― ― ― ―
 

Morse Code Communications and Vietnamese Characters

CÁC DẤU
CHỮ CÓ DẤU
COMMUNICATION:
CODE
Dấu Sác; (S)
Chữ Â; (AA)
FROM SENDER:
CODE
Dấu Huyền; (Q)
Chữ Ă; (AW)
Mời Nhận Bản Tin; (AAAA):
• ― / • ― / • ― / • ―
Dấu Hỏi (Z)
Chữ Đ; (DD)
Truyền Lầm; (HH):
• • • • / • • • •
Dấu Ngã (X)
Chữ Ê; (EE)
Hết Bản Tin; (AR):
• ― / • ― •
Dấu Nặng (J)
Chữ Ô; (OO)
Cấp Cứu; (SOS):
• • • / ― ― ― / • • •
 
Chữ Ơ; (OW)
FROM RECEIVER:
CODE
 
Chữ Ư; (UW)
Sẵn Sàng Nhận Tin; (K):
― • ―
 
Chữ ƯƠ; (UOW)
Xin Truyền Lại; (IMI):
• • / ― ― / • •
 
Xin Đánh Chậm Lại; (VL):
• • • ― / • ― • •
 
Xin Chờ Đợi; (AS):
• ― / • • •
   
Thổi Lại Chữ Trước; (C):
― • ― •
   
Hiểu Rồi; (R):
• ― •

Morse Code Tower

Morse Tower

Representation and Timing

International Morse code is composed of five elements:

Morse code can be transmitted in a number of ways: originally as electrical pulses along a telegraph wire, but also as an audio tone, a radio signal with short and long tones, or as a mechanical or visual signal (e.g. a flashing light) using devices like an Aldis lamp, a scout's whistle, (like the one the huynh trưởngs use during sinh hoạt or trại) or a heliograph.

Morse messages are generally transmitted by a hand-operated device such as a telegraph key, so there are variations introduced by the skill of the sender and receiver - more experienced operators can send and receive at faster speeds. In addition, individual operators differ slightly, for example using slightly longer or shorter dashes or gaps, perhaps only for particular characters. This is called their "fist", and receivers can recognize specific individuals by it alone.

The speed of Morse code is measured in wpm or cpm, according to the Paris standard which defines the speed of Morse transmission as the timing needed to send the word "Paris" a given number of times per minute. The word Paris is used because it is representative for a typical text in the English language, and the choice was influenced by the fact that the decision was taken at the International Telegraph Conference in Paris 1865.

Techniques on How to Learn Morse Code

People learning Morse code using the Farnsworth method, named for Donald R. "Russ" Farnsworth, also known by his call sign, W6TTB, are taught to send and receive letters and other symbols at their full target speed, that is with normal relative timing of the dots, dashes and spaces within each symbol for that speed. However, initially exaggerated spaces between symbols and words are used, to give "thinking time" to make the sound "shape" of the letters and symbols easier to learn. The spacing can then be reduced with practice and familiarity.

Another popular teaching method is the Koch method, named after German psychologist Ludwig Koch, which uses the full target speed from the outset, but begins with just two characters. Once strings containing those two characters can be copied with 90% accuracy, an additional character is added, and so on until the full character set is mastered.

One last method that usually works is PRACTICE, PRACTICE, PRACTICE. =)

Download Morse Worksheet here: .doc | .pdf

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