Create your radio station, with Fldigi
Fldigi is a free program that relies on the system sound card to receive and transmit audio-frequency signals. It works together with a standard HF SSB radio transceiver.
The program supports all usual modes such as FM, AMS, LSB, RTTY, MFSK16, DominoEX, MFSK, Throb, Hell, Olivia, CW and PSK. Fldigi lets you control the transmitter, read incoming signals and tune the high-frequency propagation.
The application features a built-in signal browser, automatic mode detection and tuning, text capturing options, rig controlling capabilities, data logging and advanced appearance customization options. Common tasks can be automated using macros.
Overall, Fldigi is rather easy to use, yet very demanding if you need to exploit its full potential.