CW can utilize the program ebook2cw by Fabian Kurz for the generation of audio tones. This makes some extra configurations possible with respect to tonal characteristics, including using square and triangle waves, instead of sinewaves, and adding noise to the CW signal to simulate radio interference (QRM).
Further information regarding ebook2cw can be found here.
Installation instructions for ebook2cw are available here.
Path to ebook2cw
If CW can’t find ebook2cw it is possible to define the path using the command ebook2cw_path:
cw do ebook2cw_path: "/usr/bin/ebook2cw" wpm 20 word_count 4 end
Alternatively, the path may be included in the .cw_config file.
## Adding noise
To add noise to the test (to simulate radio noise) you may use the noise command: require “cw”
cw do use_ebook2cw noise word_count 4 test_words end
To generate squarewave tones, use the set_tone command:
cw do use_ebook2cw set_tone_type :squarewave word_count 4 test_words end
To generate sawtooth tones:
cw do use_ebook2cw set_tone_type :sawtooth wpm 20 word_count 4 test_words end
Space between words may be added seperately (inter-word spacing as opposed to inter-letter spacing) using the word_spacing command:
cw do use_ebook2cw wpm 20 word_spacing 12 word_count 4 test_words end