The digital modes have become very popular with amateurs because of the availability of lots of free software to run on PCs with sound cards. There are regions of the spectrum reserved for the digital modes. Most software includes a waterfall display to help tuning and identification. Here are some examples of the free software programs available for monitoring and sending the various digital communication modes. They require an HF LSB/USB receiver, a lead to connect the audio output to the microphone input of the PC sound card, together with the appropriate software.
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