MORSE CODE
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Computer Science
Amateur Radio
Morse Code
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Listen to a very nice telegraphy poem written by a pennsylvania preacher in
1848. The speed is exactly 12 wpm which is required to obtain the amateur radio
license for shortwave. (A klick on the morse key will start the midi file.)
Why is there a "Morse code Page" on my homepage ?
Maybe you already know that I'm very interested in all areas of communications. As Morse code is a method of transmitting messages and data from one station to another, I'd like to bring up some information about this great invention. Everybody who works in telecommunications should have some knowledge about a famous method of communication which, historically, has even saved lives. Morse code was used for long distance communication long before modern sophisticated methods.
What is "Morse code" ?
Morse Code is named by its inventor, Samuel Morse (1791-1872), who was an artist and amateur scientist.
Samuel Morse (1791-1872)
1835 he designed prototypes of magnetic transmitters and receivers. His idea
was to use an electromagnet, already invented by Joseph Henry (1797-1878) to
transmit signals over a long wire between transmitter and receiver. At this
point, he faced a basic problem:
Whenever direct current (DC) is used to transmit signals, only two options are
available: either current flows or it doesn't. So Morse had to invent a code
which transforms every letter of our alphabet into a combination of those two
states. In other words, he had to kick off the age of digital signal
processing, even before people were able to transmit analogue signals!
How does Morse code work?
As already mentioned in the paragraph above, the Morse code allows each letter
of the alphabet to be transmitted using only two electrical states. The code
for the letters consists of short and long pulses interrupted by a short pause.
A long pause indicates the beginning of a new word.
The really cool thing about this code is that Morse already introduced some
sort of data compression by considering the probability of occurence of each
letter. For instance, the letter "e" is the letter which occurs most often in
English and its corresponding morse signal is just a short pulse. The "q",
which does not occur that often, is represented by "long pulse / long pulse /
short pulse / long pulse". As you can imagine, this makes transmission really
efficient!
You can decode Morse code by either printing the pulses to paper with a special
device, or by making the signals audible and brain-decode it "on-the-fly". A
trained person can easily copy about 100 characters per minute.
The following table shows the according Morse code for each character:
| A .- | N -. | 1 .---- |
| B -... | O --- | 2 ..--- |
| C -.-. | P .--. | 3 ...-- |
| D -.. | Q --.- | 4 ....- |
| E . | R .-. | 5 ..... |
| F ..-. | S ... | 6 -.... |
| G --. | T - | 7 --... |
| H .... | U ..- | 8 ---.. |
| I .. | V ...- | 9 ----. |
| J .--- | W .-- | 0 ----- |
| K -.- | X -..- | = -...- |
| L .-.. | Y -.-- | . .-.-.- |
| M -- | Z --.. | ? ..--.. |
Some more history
Around 1870, Morse's telegraphy system became very famous and gained a lot of
notoriety. However, some people were skeptical. They were afraid of the
telegraphy wires influencing their health and even blamed the wires for crop
failures and bad weather.
(If we replace the word "telegraphy wires" with "mobiles", it's about the same
problem we have today.)
Up to now, I've mentioned only transmission using a wire. What about wireless
transmission of Morse code ?
Gugliemo Marconi (1874-1937) was the inventor of the first wireless radio. In
1901, he sent signals from Cornwall to Newfoundland using a tube filled with
metal filings as a receiver. Again, the problem was that there were only two
states : signal or no signal. Thus, Morse code was successfully used
with wireless Marconi radio systems. The most famous Marconi transceiver was on
board of the "Titanic" which sunk in 1912 after being hit by an iceberg. Its
callsign was "MGY".
Listen to Titanic's distress signals
(wav)
The text you can hear is : "CQD CQD SOS SOS CQD DE MGY MGY MGY"
Where is the Morse code today?
Well, this is a very sad chapter. Computers and satellite technology have replaced the good old fellows sitting in their telegraph offices with headphones on their ears. Nowadays, messages can be transmitted much faster by other methods using high-speed network nodes and optical wave guides.
Morse code had to give way computer-driven modes on all ships. Today, an SOS call is sent by pressing just one button. The position, identification and further important data of the ship in danger would be transmitted automatically via satellites.
However, there are still some frequency ranges on shortwave where you can listen to Morse code transmission, usually referred to as "CW" (continuous wave).
CW can often be heard between 7.000 MHz and 7.040 MHz, and between 14.000 MHz
and 14.050 MHz. These frequencies are in the amateur radio bands. CW skills are
still necessary to obtain an amateur radio license for short wave (HF)
transmission. And, it's my opinion that this traditional rule be maintained.
For when mastery of Morse code is no longer required to obtain an amateur radio license then this long-standing and traditional method of reliable communications will die !
How to learn the Morse code ?
There are many programs available for your PC to help you in learning Morse code. Understanding the Morse code fluently by hearing an audio stream is the most difficult. Basically, you should learn how to receive Morse code first before operating a Morse key. Furthermore, it is very important to keep practicing on a daily basis. Fifteen minutes a day should be enough to make slow progress. But you must do this training practice at least 15 minutes every day.
Get a useful program which helps to learn Morse code: