PSK 31 is probably the most popular digital mode being used in Ham Radio today. It is successful at low power using minimal antennas and basic HF transceivers; you can work the world with 5 to 45 watts, a simple dipole, any radio, an interface like the SIGNALINK, a computer and some free software. Some of the newer radios operate PSK 31 without a computer or interface, but to experience the true capabilities of PSK 31 you will want to use a computer and an interface.
PSK 31 uses only 31 Hz bandwidth for communication. It doesn't get any narrower, and on a frequency being used for PSK 31 QSOs you will regularly see around 20 stations sharing the frequency, conducting QSOs and not interfering with each other. For the technically inclined, "PSK" stands for "Phase-Shift Keying" and the "31" is obvious. It has been around since 1998. Even the oldest radios are compatible with PSK 31, once you configure everything. Modern rigs use the data mode, while older rigs use the RTTY function, possibly in reverse, or USB. One of these will work in any radio. The SIGNALINK interface uses the interface soundcard, while other interfaces use the computer soundcard. You must connect the radio to the interface and the interface to the computer; the soundcard is the key to receiving and sending PSK 31.
Software is widely available on the Internet and is free. DIGIPAN and DM780 are the most popular, with DM780 being found only within Ham Radio Deluxe, which is free radio control software. You don't need to use Ham Radio Deluxe radio control software to use the DM 780 feature. The advantage of DM 780 is that it can connect to PSK Reporter using the "Super Browser" feature of the software. This automatic reporting feature of PSK 31 allows you to view all stations copying your transmissions around the world as well as logging all stations you are copying, whether or not you have a QSO with the station your system is copying. Try PSK Reporter and you will soon be addicted to PSK 31 and PSK Reporter.
For more information on both here are a few links. ENJOY:
psk.gladstonefamily.net/pskmap.html
Just GOOGLE PSK 31 to read and learn more about PSK 31
You will find plenty of activity on these frequencies:
1838.150 3580.150 7035.15 and 7070.15 10142.150 14070.150 18100.150 21080.150 24920.150 28120.150