This page is dedicated to the mode PSK 31.
PSK (phase shift keying) is a 31 baud, keyboard to keyboard mode that uses very narrow bandwidth, almost as narrow as CW. PSK is becoming a very popular mode. PSK is 100% duty cycle, so you would not want to run a 100 watt radio over 50 watts, when using PSK. Most folks run somewhere in the 15–25 watt range, some less, and some more.. PSK does very well on low power, because of the narrow bandwidth. It takes less power to push a narrow signal through the atmosphere, than a wider bandwidth signal. I had a very satisfactory QSO with an amateur on another continent who was using only 1 watt of power. I have also had satisfactory QSO's when I could barely hear a signal.
There are three basic steps to set up a PSK station:
Install PSK software on your computer. There are several very good free programs out there, and also some shareware programs. Personally I use Zakanaka, set up with Logger, which makes it easy for me to keep good records of my PSK contacts.
Install an interface between your radio and computer. At first I tried using VOX to switch my radio between transmit and receive, but didn't achieve very satisfactory results. Sometimes my radio would not switch back to receive when it should, and sometimes it would not switch to transmit when I wanted it to. I found that switching the radio through a serial port on the computer was a much more reliable method. For my interface I use a Buxcomm Rascal, which I purchased as a kit and built in a very short time.
Adjust the settings on your soundcard. When you transmit PSK you want to see very little or no movement of the ALC meter on your radio. This makes a much cleaner PSK signal and also stops undesirable sidebands on your transmitted signal which would interfere with other stations running close to your frequency.
Links:
http://www.arrl.org/tis/info/psk31.html
http://www.packetradio.com/bbbb.htm
http://home.teleport.com/~nb6z/psk31.htm
Links to the equipment and software that I use: