Principles

Teaches decoding Morse code. Ideally it does this using a rough version of the Koch method and Farnsworth timing as described in http://www.justlearnmorsecode.com/ (which also provides Windows software with many more features). In practice there isn't an interface for either of these yet, but for Farnsworth timing you can edit the constants CHAR_SPACE and WORD_SPACE in src/audio.rs and rebuild, and for Koch method you can comment out unwanted characters in src/encoding.rs.

Setup + requirements

Project is written in Rust and built using cargo. Installation link and documentation can be found at https://www.rust-lang.org/en-US/install.html.

Uses the beep utility to make sounds, so probably needs Linux.

Beep volume is set separately from normal volume, and you will probably want to lower it before using this program. Run alsamixer, press F6, and select a sound card to access fine-grained volume settings. There should be a Beep setting shown.

On my machine at least, whether beep will produce a sound is not very consistent but it seems to depend on several things:

• Laptop should not be running on battery.
• If laptop is running on battery and failing to beep, running speaker-test in another terminal re-enables beep at least for the duration of the test. This could be superstition on my part though.

If the program is stopped with ctrl+C while it is playing a tone, the current tone may continue sounding. This is annoying, but running beep in a terminal when this happens should make it stop.

$ sudo apt-get install beep
$ sudo apt-get install rlwrap # Optional but recommended
$ cargo build

Operation

Basic operation: play groups of random characters, with upper and lower bounds on word length and count.

$ ./target/debug/morse          # Default: 5 words, each 5 characters long
$ ./target/debug/morse 3 2      # 2 words, each 3 characters long
$ ./target/debug/morse 3 5 2 10 # 2 to 10 words, each 3 to 5 characters long

Use a dictionary file. Here, play exactly one word of exactly three letters. This is a good way to exercise auditory memory: don't start typing until the entire word has played.

./target/debug/morse -d 3 3 1 1

Note: The location of this file is currently hard-coded. To change it, you can edit the constant DICT_FILENAME in src/main.rs and rebuild.

Use a text file. Here, play this README ten words at a time, starting 30 words into the file.

./target/debug/morse -t "README.md" -o 30 10

Misc other options:

• -p Set pitch in Hz. Default pitch is 440, ie A above middle C.
• -l Set dot length in ms. Default dot length is 80, corresponding to about 15 words per minute.
• -c Filter words to use only ones containing all listed characters. Can be useful for focused practice.
• -m Choose character set, if not reading through a text. Default is letters only, all is all characters, and num is digits only.

Since I did not use readline, I recommend preceding all commands with rlwrap to make it easy to correct your copy (eg fill in missing letters if you can make a good guess) before entering it.

$ rlwrap ./target/debug/morse

TODO

• Flags for Farnsworth timing
• Some usable way to do Koch method
• Support other OSes. Pull requests welcome if anyone wants to make this happen.
• Misc cleanup, eg don't hardcode dictionary location