Science Notebook - Morse Code

Morse code has been around for over a hundred years. For many years before people could talk with one another using a telephone or radio, many depended on sending and receiving messages using a code of dots and dashes known as Morse code. This code was invented by the inventor of the telegraph, Samuel Morse, and its first use was to send and receiving messages over long distances using the telegraph.

People quickly realized that Morse code could also be sent my using flashing lights or signal flags, and ships at sea quickly began using it to communicate with each other, as did the military.

And when radio was first invented, the only means of communication by radio was Morse code as well. It would take several more years to figure out how to send and receive voices over the air. But even long after voices could be sent by radio, people still used Morse code to send in receive messages on land and sea, as well as in the air. Morse code was often used because the signals could be heard much farther than voice communications, and with simpler equipment.

But as radio communication equipment improved, Morse code was used less and less, and today it has largely been abandoned in favor of digital signals that can be sent much faster and can carry much more information.

But Morse code is not entirely dead. It is still used and enjoyed by amateur radio operators (also known as "hams") around the world. For many years, one of the requirements of a ham radio license was the ability to send and receive Morse code, but in the last few years, most countries have dropped the code requirement. Still, although hams are no longer required to learn Morse code to obtain an amateur radio license, many still take the time to learn it on their own. These hams regularly enjoy communicating using Morse code. In addition, there are still some individuals and outdoor groups who use Morse code to communicate with each other using flashing lights or by "wigwagging" signal flags.

Maybe you think it would be fun to try your hand at communicating with Morse code, but you are put off by the fact that Morse code might take some work to learn. Well, let The Science Notebook staff let you in on a little secret. It is a little hard to learn, but not as much so as you might think. And just think of the fun you can have communicating once you do!

To give you an idea of how much fun you can have with Morse code, we're going to show you a code known as "tap code" that you can begin using right away! Once you have learned to use tap code, The Science Notebook hopes it will encourage you to learn Morse code! The tools to learn Morse code are available right here, and they are free!

What Is Tap Code?

Tap code was used by American prisoners of war during the Vietnam War to communicate with one another inside POW camps when talking was not allowed. Although American POWs were punished, and sometimes severely, for talking with one another, they were able to keep track of what was going on inside the camp by means of tap code without their guards knowing what they were up to.

Tap code is very easy to learn, and it can be sent and received using many diferent methods including tapping (naturally), a simple telegraph, radio, flashing lights, and flags, just like Morse code. In addition, you can use hand signals, and probably many other ways as well!

So How Does Tap Code Work?

Special thanks to Nyle, K7NS, for suggesting an important correction to this material!

The tap code is based on a 5×5 grid of letters, representing all the letters of the alphabet, with C and K sharing the same code. Each letter is represented by two numbers. Take a look at the chart below:

Tap Code Chart

	1	2	3	4	5
1	A	B	C/K	D	E
2	F	G	H	I	J
3	L	M	N	O	P
4	Q	R	S	T	U
5	V	W	X	Y	Z

Notice that there ia a number at the top of each column on the chart, and a number for each row on the left side of the chart. The code for each letter is found by first locating the letter you want to send. The code for that letter consists of two numbers. The first number is the number in the row to the left of the letter, and the second number is the number in the column above the letter.

For example, the two digit code for the letter "W" is 5-2. (The dash is there just to show the space between the two numbers.) The first number (2) is number in the row above the W, and the second number (5) is the number in the column to the left of the W. The order is ROW first, and COLUMN second!

You can decode tap code as it as it is being sent using the above chart if the person is not sending too fast. You can also send tap code by any of the same methods you could use to send Morse code. However, the main disadvantage of tap code is that it takes longer to send each letter than it would in Morse code, but you can even work around that to some extent.

Sending And Receiving Tap Code

To send a tap code for the letter "W", you would tap five times, pause, and then tap twice, like this:

"tap tap tap tap tap (pause) tap tap"

Using dots to represent taps, the code for "COME HERE" would be:

C	O	M	E		H	E	R	E
1-3	3-4	3-2	1-5	pause	2-3	1-5	4-2	1-5
. ...	... ....	... ..	. .....		.. ...	. .....	.... ..	. .....

To send this message, you would make the number of taps for the first number, pause, and then tap the second number. Leave a longer pause between letters. Be sure to send this slow enough that the other person has time to copy each letter. After a while, you will have memorized the codes for each letter and will be able to send and receive much faster, but never send any faster than you can receive!

To receive this message listen carefully for each pair of taps and write down the two numbers. When the sender is done, decode the message by going along the top row to the first number and then straight down to the second number on the column to find your letter!

It will take some practice to do this with any speed, but with the above table, you can begin to use tap code right away. As you practice, you will begin to recognize the number pairs for each letter and you won't have to use the chart.

You may find it a little bit tedious to send or receive one letter at a time, but we'll show you some shortcuts a little later.

More On Sending And Receiving Tap Code

When you are just starting out, send slowly. You need to give the person on the other end plenty of time to count the taps and write them down. If you want them to copy each letter as you send it, you will also need to give them time to locate the letter. The more you practice, the faster you can send and receive, but never never send faster than the other person can copy!

Be sure to leave short pauses between each number in the pair. Leave longer taps between number pairs, even longer gaps between words, and the longest gaps between sentences.

Remember that the tap code for the letter K is the same as for the letter C, so if the word you receive is first copied as CNIFE, you should see that the word is really KNIFE.

If you are copying tap code and miss a letter, you can send a string of taps. You can also do this if you send the wrong letter.

Other Ways To Send Tap Code

You are not limited to sending tap code by just tapping. There are lots of different ways that will work, particularly once you have memorized the letters. Here are just a few.

Flashing Light - You can send tap code at night over a long distance using a flashlight or any other light that you can turn or off easily. If the light won't turn or off easily, you can put a piece of cardboard over the light and flash the light by uncovering and covering it. You can also flash the light by moving it from behind a tree trunk or other object and back. In the daytime, you can use a mirror to flash reflected light, although it will take some practice.

Flag or Other Signal - You can send tap code during the day over a long distance by using a flag to send the numbers. A piece of cloth tied to a stick will do fine. Starting with the flag hanging straight down, lift it up to your side and back down for each tap. Depending on the size of the flag and its color, this can work over a fairly long distance. You can also make signals using just a stick, or a stick with a piece of cardboard attached. Can you think of other ways?

Your Hand or Hands - Since it just so happens you have five fingers (or if you insist, four fingers and and a thumb) on each hand, you can easily send tap code just by using the fingers on one hand. Instead of taps, you would simply hold out the number of fingers required for each number.

Using Tap Code to Communicate

Now that you know the basics of tap code, you can begin using it right away. Grab a friend and a couple of note pads, decide which method you want to use, and begin practicing. You can use this on camping trips, between rooms at home, or hundreds of other places. Use your imagination!

A Simple Telegraph Set

To help you use tap code with sound, you can make this telegraph set so that you can send and receive with a friend. With a second set and one or two outdoor extension cords, you can send and receive a couple of hundred feet or more!

Materials Needed: To make a single unit you will need one buzzer unit (RadioShack mini-buzzer, 273-0053 or similar); small piece of wood for the base; a battery holder that will hold two C or D cells; 5 small sheet metal screws; a disposable aluminum food pan; clip leads or covered wire. (Clip leads are really good for connecting the battery and the wires between stations, but you can make do with insulated wire.)

Procedure: The unit shown above uses a homemade battery holder for two C or D cells. You can buy a battery holder at RadioShack or online, but you can make one for almost no cost following the instructions found HERE. If you want to buy your own battery holder, skip the next couple of paragraphs.

If you don't have clip leads and will be using covered wire, make the battery holder as instructed. You can get covered wire for free from an old string of Christmas tree lights. (See more information on the homemade battery holder instructions found HERE.) You can also use the "zip cord" from a non-working drop cord or electrical cord from a broken appliance. This cord has two strands that con easily be split apart. Each side makes a single length of insulated wire,

If you have clip leads and want to make the homemade battery holder, instead of putting wires on either end, cut two small strips of aluminum from the food container. (You should be able to cut the aluminum easily with a good pair of scissors.) Each strip should be about 1/4 inch longer than the width of the cell. Tape one strip to the positive terminal of one cell and the other strip to the negative end of the other cell. One end of each strip should stick out about 1/4 inch so that you can attach the clip leads. Finally, place the rubber band around the two cells, and make certain it pressed firmly against the metal strips. This will give you a nice tab on each end on which to fasten a clip lead.

Most buzzers available today are piezo buzzers that work correctly when attached to the battery one way only. Notice in the photo that the red wire coming from the buzzer attaches to the positive or (+) end of the battery, and the black wire attaches to the negative or (-) end of the other battery. Black wire almost always indicates negative and red wire represents positive. The clip leads attached to the battery in the above picture follow this code. Of course, the color of the wire you use is not important, but getting the buzzer hooked to the right ends of the battery is, and the buzzer wires are color coded so that you will get it right.

This particular buzzer will operate with a voltage of 1.5 to 3 volts. We are using two cells to give us 3 volts because we are building this to work with another unit of the same kind and attaching the units with a long electrical cord, so we want to use the higher voltage. Touch the (+) end from the battery holder to the red wire on the buzzer and the (-) end to the black wire. The buzzer should sound. If not, check all of your connections and be sure that you have the right wires connected to each end of the battery.

Next, mount the buzzer on the board. You can mount it using very small screws, double sided foam tape, glue, etc.

Now cut a small strip from the aluminum pan about 3 1/2 to 4 inches long and 1/2 inch wide. Make a sharp bend in this piece about 1/2 inch from one end. This will be the telegraph key.

Finally, cut three strips of aluminum 1 1/2 inches long and 1/2 inch wide. Fold each of these strips over the long way to form a two layer strip about 3/4 inch by 1/2 inch. Also cut two pieces of insulated wire about 3 inches long and strip about 3/4 inches of insulation from each end of both wires.

Mount the key (the long aluminum strip) at the bent end by screwing it into the wood with a sheet metal screw. Before you tighten the screw completely, wrap the bare end of one of the wires around the screw along with the bare end of the black wire from the buzzer unit. Finish tightening the screw, making sure that the metal strip, screw and the two wires all make good contact.

Screw another sheet metal screw underneath the other end of the metal strip. This will be the contact for the key. Before you tighten the screw completely, wrap one bare end of the other wire around the screw and finish tightening. Make sure the contact between the screw at bare wire is good.

Using screws, fasten the other bare end of each wire and a 1/2 by 3/4 folded aluminum strip to the edge of the board as shown in the photo. The folded end of each strip should hang off the edge of the board enough to make a good surface to fasten a clip lead. If you don't have clip leads, you can just fasten the bare wire strips to the board and fasten other connecting wires later. Some hints for connecting wires may be found HERE on The Science Notebook Electricity pages.

Finally, mount the red wire to the board using the third folded strip and a screw.

Now connect the positive end of the battery to the red wire using a clip lead or one of the other ways of connecting wires on the Electricity pages (see above). Connect the negative end of the battery to the wire coming from the screw underneath the metal strip. For right now, you do not need to attach wires where the green and yellow clip leads are shown.

Checking It Out: If everything has been wired correctly, the buzzer should sound when you press the key. If not, check all your connections against the picture above, and be sure that the connections are tight.

Going Further: Once it is working properly, you have a nice buzzer set you can use to send or receive either tap code or Morse code. But for real fun, you or a friend can build another unit and connect the two together to make two telegraph stations. Let's see how...

Connecting Two Telegraph Sets

Materials Needed: Two telegraph sets made using the plan above; a disposable aluminum food container; clip leads or wire; one or two long outdoor electrical extension cords; tape (optional). NOTE: The extension cords will not be harmed in any way.

CAUTION! The extension cord(s) are used to connect the two sets together. While you are using any cord for this purpose, it should NEVER EVER be plugged in! Otherwise, you might get a very nasty electrical shock - or much worse! If you don't understand this, please go play with something else!

Procedure: You can use an extension cord with either two or three prongs. Almost all outdoor cords have three prongs - two flat ones and a third round one. If you have an extension cord with three prongs, you will only use the flat prongs.
Connect clip leads or wires to each telegraph set where the green and yellow wires appear in the illustration in the last activity. Connect the other ends of each of these these wires (or clip leads) to the blades of the plug on the drop cord. It is a really good idea to hook up to the plug end first so that you don't accidentally plug it in later!

Next, after making absulutely certain that the plug end is attached to the other set and NOT plugged into the wall, cut two small strips of aluminum from the aluminum food container about four inches long and not quite as wide as the slots in the socket end. Fold each strip over the long way twice so that you have two strips that are each one inch long. Insert the folded end of a strip into each of the flat slots in the plug.

If you are using clip leads, fasten a clip lead to each strip, being sure that the two leads don't touch. If you hear a low buzz, that means the wires should be reversed.

If you are using wire with the ends stripped, tuck the bare end of each wire between the fold of each aluminum strip. Again, if you hear a low buzz, that means the wires should be reversed.

Press one of the keys. If everything is working correctly, both buzzers should sound. Next, press the other key. Again, both buzzers should sound. If not, check your connections carefully and try again. If any of the connections are loose, you can secure them with tape as necessary.

Using the Stations: Once you have the two stations working, you can move them into different rooms, or even different houses. They can also be used between two tents while you are camping. The longer your extension cord, the farther you can move them apart. You can connect two different extension cords for greater distance. By using batteries on both units, and by using two cells to produce 3 volts instead of 1 1/2 on each unit, these units worked well up to 200 feet. They might work over a much greater distance, but we only had two drop cords!

You can immediately use thse to send and receive tap code, and if you decide to learn Morse code, two sets connected together will make learning and practicing a lot more fun!

Tap Code Shortcuts

OK, now that you know how to send and receive tap code and have several ways to do so, let's learn some shortcuts!

If you have ever chatted over the Internet or texted over a cell phone, you already know a lot of shortcuts you can use with tap code, such as LOL for "lots of laughs".

You can also use these shortcuts used by ham radio operators who send morse code:

Send the letters BK to say you are finished for now and waiting for the other person to start sending.
Send the letters AR to say you have finished your message
Send the letter R to say you received the last message
Send the letters CL to say you clearing (quitting)
Send the letters AS to tell the other person to wait or stand by.

Code Book

If you use the tap code a lot, you can really save time by making a code book. A code book consists of all the shortcuts you use, such as the texting and ham radio codes mentioned above. You can also make thousands of three letter codes to represent words, phrases, or whole sentences. In fact, if you use all the the letters except K (since it has the same tap code as C), you can make as many as 13,800 different codes!

MATH BREAK - the total number of possible combinations is 25 times 24 times 23 which eaquals 13,800.

Let's see how that works.

Start with the lowest combination of three letters you can make alphabetically and work your way up. We'll do the first ten.

Now decide what each three letter group will mean. You can pick out words, phrases or sentences that you use a lot. For example:

AAA Meet me
AAB At my house
AAC At your house
AAD At school
AAE At the store
AAF In camp
AAG Tonight
AAH Tomorrow
AAI As soon as possible
AAJ In one hour

You should be able to see that you can send a lot of sentences with just these ten groups. For example, "Meet me at the store in one hour" can be sent with just three letter groups - AAA AAE AAJ. This would be nine pairs of numbers in tap code.

Of course, you can use as many words, phrases or sentences as you want, but you should list your letters alphabetically so that the meaning is easy to find. Also, you don't want to have so many that you spend too much time looking them up. It is best to use only for long words, phrases or sentences you send often.

An Example of a Code Book

This is a sample code book that uses only two letter combinations. As noted above, using three letter code groups, you can make as many as 13,800 different combinations, but you would never use anywhere near that many. However, using only a two letter code, you can have almost 600 (25 x 24 = 600) different combinations. You can't get qiute that many, though, because a few of these combinations are actually words (me, go at, we) or abbreviations used above. Still there are more combinations left than you would ever use.

Take a look at these and see just how many different messages you could send.

Abbreviations

AR	End of message (sent only at the end of the message)
AS	When sent by itself, it means wait or stand by
BC	Because
BK	I am through sending and waiting for you to respond
CD	Could
CL	Through sending or receiving, and I am quitting
FT	Foot or feet
MI	Mile or miles
N	In
R	The word "are," or when sent in response to a message or part of message, "message received."
RP	Repeat your message
SD	Slow down. Send slower.
SU	Speed up. Send faster.
U	You
UR	Your
WN	When
WO	Who
WR	Where
WT	What
WY	Why
WD	Would
YD	Yard or Yards

Numbers
(since tap code does not include numbers)

NA	1
NB	2
NC	3
ND	4
NE	5
NF	6
NG	7
NH	8
NI	9
NJ	0

Verbs

AA	Come
AB	Find
AC	Go
AD	Have
AE	Help
AF	Look
AG	Meet
AH	Need
AI	See
AJ	Send
AK	Swim
AL	Want

Verb Tenses

    To make tenses, add a third letter

    Add D for past tense
        AAD = came
        AJD = sent

    Add W for future tense
        AAW = will come
        AJW = will send

    Add G for perfect tenses
        AAG = coming
        AJG = sending

Nouns

CA	Food
CB	House
CC	Lake
CD	Pond
CE	Road
CF	Room
CG	Store
CH	Tent
CI	Trail

Plurals

    To make plurals, add S
        CBS = houses
        CIS = trails

If you want to add others, you can. If you don't think you would use some of these, leave them off. The idea here is to make it easier for you to send messages quicker, rather than harder, so you probably would not want more than 100.

Complete Phrases or Messages

Part of that hundred could be complete phrases or messages. In this example, we started with the letter Z because that should alert the person receiving that if this is a three letter code group, it is most likely a phrase or sentence code. If you want to send only two letters, you can still have plenty of different combination just beginning with the letter Z.

ZAA	Can you come over to my house today?
ZAB	Let's go fishing!
ZAC	Do you have a lot of homework?

To make the actual code book, you should list all your codes and abbreviations twice. The first time, they should be sorted into alphabetical order by the word, phrase or sentence. This list will make it easier for the sender to find the right code or abbreviation. The second list should be alphabetized by code or abbreviation. This will make it easier for the receiver to decode the final message.

If this sounds like a lot of work... well, it is. But it will help you make tap code really useful.

Morse Code Revisited

Once you have had a chance to use tap code for a while, you will notice that while it is easy, it does take some time to send and receive simple messages, even using shortcuts and special codes. However, if you have found using tap codes to be fun and useful, you can speed things up a lot by learning Morse code. Morse code is a little more difficult to learn to begin with, and it really does have to be memorized to be useful, but if you take the time to learn it, it will speed things up for you quite a bit once you do.

Take a look at the International Morse Code chart below.

International Morse Code

Character	Code	Sound	Character	Code	Sound
A	. -	di dah	U	..-	di di dah
B	-...	dah di di dit	V	...-	di di di dah
C	-.-.	dah di dah dit	W	.--	di dah dah dah
D	-..	dah di dit	X	-..-	dah di di dah
E	.	dit	Y	-.--	dah di dah dah
F	..-.	di di dah dit	Z	--..	dah dah di dit
G	--.	dah dah dit	1	.----	di dah dah dah dah
H	....	di di di dit	2	..---	di di dah dah dah
I	..	di dit	3	...--	di di di dah dah
J	.---	di dah dah dah	4	....-	di di di di dah
K	-.-	dah di dah	5	.....	di di di di dit
L	.-..	di dah di dit	6	-....	dah di di di dit
M	--	dah dah	7	--...	dah dah di di dit
N	-.	dah dit	8	---..	dah dah dah di dit
O	---	dah dah dah	9	----.	dah dah dah dah dit
P	.--.	di dah dah dit	0	-----	dah dah dah dah dah
Q	--.-	dah dah di dah	Period	.-.-.-	di dah di dah di dah
R	.-.	di dah dit	?	..--..	di di dah dah di dit
S	...	di di dit	Comma	--..--	dah dah di di dah dah
T	-	dah	/	-..-.	dah di di dah dit

You'll notice that each letter, number and punctuation mark is represented on paper by a series of dots and dashes. Morse code can also be sent using sound or light, but unlike tap code, a dot is represented by a short sound or flash, and a dash is represented by a sound or flash that is about three times longer. There are several good programs and a free podcast class on the Technology section of the Useful Downloads page that will help you to learn code by either sound or flashing light. No matter which one you use, you should try to learn every letter as a single sound or flash pattern instead of trying to count the dots and dashes. You will learn much faster that way!

Why Is Morse Better Than Tap Code?

There are several reasons.

First, tap codes take longer to send. Letters in tap code can require up to ten taps. If you study the tap code table, you will see that of the 26 letters of the alphabet only 7 can be sent with four taps or less, and two of those - C and K - share the same code.

Using Morse code, every character in the alphabet can be sent using a combination of no more than four dots and dashes, and most use three or less. Also, in Morse code, every letter of the alphabet is represented since C and K each have their own unique code.

In addition, Morse code has codes for each of the numerals, and each uses no more than five dots and/or dashes. Morse code also has punctuation marks, and these require no more than six dots and/or dashes. Tap code does not have either numbers or punctuation.

The bottom line is that takes less than half the time to send letters in Morse code than using tap code, so if you want to use code to communicate, Morse code is much better than tap code, even though it is a little harder to learn.

For other codes you might find fun, check out the Gilbert Signal Engineering pages. They're old, but the codes are still useful. And if you want to learn Semaphore, check out our Semaphore PowerPoints on the Downloads page! Finally, you can find a lot more information on Morse code and amateur radio on the external site located HERE. (This external link opens in a new tab or window.) Here you will find an excellent history of Morse code as well as many other great links to explore. Check it out!

Also, there's lots more to see and do on our Experiment Pages or you can visit The Science Notebook Home !