HPR4547: Cheap Yellow Display Project Part 6: The speed and timing of Morse

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Hello, again. This is Trey. 

 

Welcome to part 6 in my Cheap Yellow Display (CYD) Project series. Thank you for hanging in there with me on this rambling series. If you wish to catch up on earlier episodes, you can find them on my HPR profile page https://www.hackerpublicradio.org/correspondents/0394.html   

 

To review, my project is to build a portable morse code "Keyer memory" which can be connected to any of my amateur HF transceiver radios by simply plugging it in to the code key input port. This is based around an ESP32 platform which comes prepackaged on a yellow PC board with a color touchscreen display, WIFI, and Bluetooth. We fondly call this contraption the Cheap Yellow Display.   

 

So far, I have defined the necessities, collected the required hardware, and failed miserably building the graphical user interface (GUI).  

 

While I sort out the technical challenges getting my GUI code to play nicely with the CYD's touchscreen, it is important that we spend some time discussing Morse code itself, and the timing standards we will need to follow. 

 

I am not going to dive too deeply into the history behind telegraphs and Morse code, but it is very interesting. If you want to learn more, Wikipedia has the origins and evolution written out quite nicely at https://en.wikipedia.org/wiki/Morse_code   

 

For our purposes, we will fast forward from the year 1820 (When telegraphy began) all the way to 1865 when the International Telecommunication Union (ITU)  standardized, what it called "International Morse Code". When I say Morse Code for the remainder of this podcast, I am referring to this ITU International Morse Code.   

 

Morse code typically includes the following characters: 

• The 26 letter basic Latin alphabet 
• The Indo-Arabic numerals 0 to 9 

 

There is also a single accented Latin letter (É), which is written as an E with an accent mark, and a handful of punctuation marks. 

 

These characters are encoded using a sequence of short and long signals. Each short signal is referred to as a dit . Each long signal is referred to as a dah . At a young age, I began to refer to them as dots and dashes, as this is how they are usually written. For example, the letter "A" consists of a single dit followed by a single dah. When written out this would look like a period followed by a hyphen (what some might call a minus sign)   .-   

 

This encoding method allows messages to be sent by turning on and off an electrical signal. This could result in a light flashing or a tone sounding to the pattern of the signal. The timing of a dit and dah, along with the spacing between them is carefully defined.    

 

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