Phase-shift keying (PSK) is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal (the carrier wave).
Alternatively, instead of using the bit patterns to set the phase of the wave, it can instead be used to change it by a specified amount. The demodulator then determines the changes in the phase of the received signal rather than the phase itself. Since this scheme depends on the difference between successive phases, it is termed differential phase-shift keying (DPSK). DPSK can be significantly simpler to implement than ordinary PSK since there is no need for the demodulator to have a copy of the reference signal to determine the exact phase of the received signal (it is a non-coherent scheme). In exchange, it produces more erroneous demodulations. The exact requirements of the particular scenario under consideration determine which scheme is used.
Source: Wikipedia: http://en.wikipedia.org/wiki/Phase-shift_keying
One of the more popular software tools for working PSK is Ham Radio Deluxe and Digital Master 780. DM 780 makes it very easy to work PSK and to view multiple signals. Since PSK alls multiple QSO's to take place at once in the bandwidth of voice transmissions, PSK31 is a very efficient method for communications. Because the bandwidth used is very small, the amount of power needed for a transmission can also be small.
The image above is a screen capture of DM780 capturing a PSK31 QSO. The screen shows the typical PSK transmit and receive windows, but more importanlty, the "Waterfall" plot. The watefall plot is a very useful tool because it represents a graphical window that allows you visualize the station that are active and transmitting within a 31 kHz bandwidth. The stronger signals have the brighter colors, while the weaker signals will not be as bright. Using the waterfall graphic really is what makes PSK31 operation easy to tune and enjoyable to work.
All that is really needed to run PSK31 is an HF radio, a computer with a sound card, an interface that connects to the PC and the transceiver such as a RigBlaster or a homebrewed audio coupled solution and Ham Radio Deluxe.
© 2019 , Jonathan Tucker N8MDP. All Rights Reserved.