Friday, August 26, 2011

Morse Code, Part I

One of Amelia Earhart's weaknesses was that she did not know Morse Code, and it seems that information wasn't communicated to the ships that were providing weather and guidance for her during her final flight. I don't know Morse Code well enough to send and receive sentences, and I discovered that I can't read visual flashes at all, but I can understand all the numbers and letters at the slow speed broadcast by nav aid identifiers.

I was triggered to learn by a ground school instructor who related what he thought was an amazing story about a student who didn't have to look at the dots and dashes provided on the charts while he was identifying the nav aid, because the student had "memorized Morse Code." I knew that memorizing Morse Code was not an amazing feat, and it sounded like a way I could get an advantage in the air. I knew already that if you can spend thirty minutes on the ground to save one minute in the air, you should do it. And you can probably learn Morse Code well enough to understand nav aid identifiers in about thirty minutes. It is not that hard. This post and the next couple are my hints for achieving that skill.

First thing is, and this doesn't count in your thirty minutes, because you'd have to learn it regardless and you probably know it already, is the idea of "dots and dashes." Morse code is produced by pulsing a signal. It doesn't have to be a wire or radio transmission or use a special device. It works with any signal. It could be light, sound, touch, arranged objects. The only requirement is that it is possible to differentiate two sorts of signal. The way to do that is usually long versus short, which is why this suggestion wouldn't work, even if the guns had been operational. Although it's a space ship, so maybe they could have pulsable laser guns.

Each letter in Morse code is between one and four pulses long, in some combination of short and/or long pulses. In transcribing a message, the short pulses are written as dots and the long ones as dashes. The short pulses are also called dits and the long ones dahs. If, like me, you learn by memorizing what things look like, you can picture each letter as its corresponding sequence of dots and dashes. They're just some associations that I use when I forget which letter is which. My suggestions here are not predicated on visual learning, though. There are also a stunning number of mnemonics on Wikipedia's page on the subject.

Morse Code You Probably Know Already: O S V

It's classic rock, but if you've heard The Police "Message in a Bottle" just once, you've heard about sending out an SOS about thirty times, so you should know what that is. The official Morse code distress call is an S, O, and S sent out with no spaces between. That's three short, three long, and three short signals. The triangle is the official shape of distress, and three is its number. All you have to do is remember that S is the three dots (...) and O the three dashes (---). O is fatter, while S is skinny, so S can is the fast three and O the slow ones.

The other letter you already know is V (...-), instantly recognizable in the "da da da dum!" of Beethoven's fifth symphony. The symphony has even been used as a code signifying victory, for that reason. You can learn three more letters in relation to V.

Letters Related to V: U B D

This is just me, so maybe this doesn't work for you, but here goes. You already know V (...-). The written letter U is just like V except without the point. The Morse U (..-) is just like V with one fewer point, too. In Spanish B and V are extremely similar sounds, so I have no problem remembering that B (-...) is V reversed. And a capital D is shaped like a capital B except with one fewer thingy. Thus we get D (-..), one fewer thingy.

The Commonest Letters: E T A

If you've ever played with word games or cryptography, you know that the most common letters in English are E, T and A, in that order. Samuel Morse must have known it too, because he made them the simplest codes. E (.) is a single dot, the commonest letter and the fastest to send. A lower case e is a bit like a single dot, too. If the font is small enough: e e e . Meanwhile, T (-) is a single dash. Like the one on top of a capital T. If you put E and T together you have A (.-). But that's not how I remember A.

The A-N Beacon: A N

One of my favourite pieces of navigation history is the four course radio range, or the A-N beacon. Its operation is dependent on the fact that A (.-) and N (-.) have opposite signals. And that's how I like to remember A and N.

Hi Dots: H I

We know one dot is E and three dots is S, which leaves two dots for I (..) -- eyes are after all two dots in the front of your face -- and four dots for H (....). I think Morse code enthusiasts probably have a special Q-code for greeting one another, but if they wanted to say "hi" it would be an easy six dots.

That's enough for today. The next part of this post isn't finished yet, so there might be a few posts in between.


Anonymous said...

You're very close about the "hi". Ham operators use it to indicate a laugh. hi, hi is ha ha. di-di-di-dit di-dit. It's almost musical.

Sarah said...

I had to receive 13 words per minute for a test back in the stone age, which I did, just barely. I doubt I could do that now - but even today I have a straight key on my bookshelf.

Anoynmous said...

The first advice I would give someone wanting to "memorize Morse Code" would be to forget about dots and dashes and counting. Just listen to the sounds of entire letters and learn the correspondence between those sounds and the letter they represent. It doesn't take long to get to the point where you can hear an entire "dahdidahdit" as one noise and immediately know it's a C.

If all you need to do is recognize slow ID strings, you can get away with listening for the individual bits of each letter and analyzing them for length and number. But you won't be saving a whole lot of cognitive load doing it that way.

Aviatrix said...

You're talking to someone who has difficulty recognizing her own national anthem without the words. :-(

Chris said...

Nice post! I've had instructors accuse me of having morse memorised as some sort of trick!

C -.-. always sounded like Charlie-Charlie to me.

Anonymous is spot on. Once you get fast you hear a sound and immediately recognise it as a letter, without the intermediate step of converting to dah-dits and then the letter.

Frank Van Haste said...

Dear Trix:

I took a run at this one a few years ago. Like you, I can pretty much recognize the identifiers.

If you care to check out a few more mnemonics, here are mine.



nec Timide said...

You're talking to someone who has difficulty recognizing her own national anthem without the words.

Trix, you need to start thinking about Morse as a 'spoken' language with the letters, rather than the dots and dashes) as the phonemes. I think that is what Anoynmous was getting at. This is particularly important for anyone who wants to develop any ability to read Morse at speed. In any case it is much easiere once you shift the processing to the linquistic centre of your brain instead of trying to deal with it in the analytical centre.

Scott Johnson said...

The interesting and magical part of Morse comes when the letters cease to matter.

Just as we see words on a page and don't spell them in our heads, so it is with Morse once you reach a certain speed. The word "HELLO" becomes a sound pattern you recognize as a word, not five letters strung together.

As a ham, I still use Morse from time to time on the HF radio bands, and I enjoy it. Morse code sent on an unmodulated carrier (known as CW or Continuous Wave) is an extremely narrow-band, power-efficient means of getting a signal through.

Sarah said...

I never got good enough to "get" whole words at a time. I think you need to get pretty fast to reach that level, and I never sent or received that fast. I can't even do the 5wpm without getting stuck on a "what was that letter periodically.

John Lennerton said...

This story brought back a memory of my flight test for my PPL; during the flight, the examiner asked me to tune the the Lawrence, MA VOR and fly outbound on a given radial. I had the frequency memorized, as it was the closest VOR to my home airport (BVY, or, as it is now known, KBVY), so I tuned it up, found the radial, and flew off. The examiner was aghast; he asked "how do you know that's the Lawrence VOR???". I told him that the identifier was correct. He wanted to know how I could possibly know that. I told him I held a ham radio license, and had memorized the Morse code.

So he actually tuned in other VORs at random and asked me to id them!

I still can't understand how he'd never suspected that someone might learn Morse. Certainly there were a bunch of local pilots who were also hams.

As for learning it, well, if you're never going to need to do it at speeds above 25 characters per minute, learn it any way you can.

Anonymous said...

here is a link to the best CW learning aid.Its how the hams get up to 20 or 30 even 40 words a minute!The mode is called CW. I.E. Continues wave and one of the languages you can use with CW is Morse.