The version of the program you are about to download is 3.66. The download is provided as is, with no modifications or changes made on our side. This is my personal preference for CW decoding. Once you learn it, it's no more difficult to use than any other program, it just has a slightly steeper learning curve. The GUI can be daunting because it's very cluttered. This download is provided to you free of charge. Paying gets additional modes not included in the free version.
If you've read this far, you may be interested in the older version of this tool which does not attempt to adapt to the sound and also includes more diagnostic information. Thank you for downloading CW Decoder from our software library. The volume threshold is the value (0-255) which the measured volume in the analysed frequency must exceed to be counted as a dit or dah. The volume filter (which uses dB) discards very quiet (very negative) or very loud (close to zero) sounds and scales the size of the remaining data.
There are three parameters which are not automatic: the minimum and maximum volume filter settings and the volume threshold setting. The frequency can only be certain values and the closest allowed value will be chosen. If you want to fix the frequency or speed then click on the "Manual" checkboxes and type in your chosen values. In fully automatic mode, the decoder selects the loudest frequency and adjusts the Morse code speed to fit the data. Connect, via the rtltcp network protocol, to networked RTL-SDR, Airspy HF+, HF+ Discovery, LimeSDR Mini, or SDRPlay RSP1A/RSP2 USB peripherals, Listen to FM and VHF radio signals. The rtltcp SDR macOS app is a Software Defined Radio client. From these timings it determines if something is a dit, dah, or a sort of space and then converts it into a letter shown in the message box. Supports Morse Code decoding at speeds up to 80 WPM. If the volume in the chosen frequency is louder than the "Volume threshold" then it is treated as being part of a dit or dah, and otherwise it records a gap (this is shown in the lower graph that looks like a barcode). The spectrogram of the sound is shown in the main graph along with a pink region showing the frequency being analysed. The decoder will analyse sound coming from the microphone or from an audio file.