Phase Shift Keying 31/63/125

PSK

PSK, or Phase Shift Keying has become the most popular of the newer digital modes. There is a wealth of information on the web regarding BPSK (Binary PSK) and QPSK (Quadrature PSK).

The higher the bandwith the higher the dataspeed. I mostly use PSK31

This mode can be generated and decoded by a variety of free software on the internet.

PSK31

Because PSK31 has a bandwidth of only 31Hz, many signals can fit into the same bandwidth that would be occupied by an

SSB signal (2400 Hz approx.). It is quite common to see 15 or more signals on a 2.5kHz waterfall display

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PSK63 & PSK125

Other variations of PSK31 are PSK63 (double the bandwidth/speed of PSK31); PSK125 (4 times bandwidth/speed) and other experimental variations such as PSK10 (to be found in MultiPSK) and even PSK250. The other common variant of BPSK31 is QPSK31, (the ‘Q’ stands for ‘Quadrature’, rather than the usual B which is ‘Binary’ Phase Shift Keying), which is sideband dependent (i.e. both transmitter and receiver must be using the same sideband) but is not in common use despite it’s superior decoding ability during poor conditions. Here is an waterfall shot of QPSK63 (the wider of the signals. If you compare it to the BPSK31 signal above, and also on the left of the picture you can see there appears to be more information contained within the same signal, this is the easy way to tell QPSK from BPSK

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