This is a Mac OS X version of the HotPaw
Morse Decoder app for iPhone and iPad.
The HotPaw Morse Code Decoder decodes the tones of Morse Code characters from audio input, and transcribes the results into text. Both an audio spectrum graph and a tone amplitude graph are displayed to assist with tuning the decoder. User configurable settings include the frequency of the narrow-band audio filter, the WPM dot/dash speed used for Morse code detection, a noise threshold level, and whether Farnsworth timing is to be used for detecting spaces between characters. If the audio filter is enabled, the filter can be set for frequencies in the range of 400 to 1400 Hz.
*** Note: The built-in microphone on many MacBook models has been reported not to work due to the pick up of fan noise and room and table reverberations of the Morse code tones. In those situations, an external microphone or line-in may be necessary to allow decoding.
The Morse code WPM (words per minute) detection speed is automatically adaptive from about 8 to 40 WPM, and can be locked to the current estimated WPM dot speed (WPM lock icon locked). There is a High Speed WPM Mode which may work better for code speeds in the range of 40 to 80 WPM.
It may take several initial and immediately preceding characters containing both dots and dashes before the WPM speed estimation starts to get close to the actual WPM. Background sounds and signal fading can interfere with detection and decoding. The quality of decode depends on the signal level, signal to noise ratio, stability of the frequency and WPM speed, keying "fist" quality, and whether you have configured the app properly for the signal.
For users who can't get the decoder to start decoding at all, the problem is likely to be an inappropriate audio level, fan noise, room echo,
a tone frequency too high, too much background noise,
or radio noise causing an unrealistic initial WPM setting. Please see the new help file on the HotPaw website for hints as to how to solve these issues. Please use the manual settings if automatic decoding does not adjust to the frequency, WPM or background noise threshold level.