PSK31 – Work The World With Low Power

(With thanks to Radio Society of Great Britain for much of the following information.)

PSK31 is a highly-efficient data mode that lets you work long distances, even when you can barely hear the signal. (PSK31 stands for Phase Shift Keying 31 baud - 31 bits per second/bps.)

Unlike RTTY (radio teletype) the characters are formed by changing the phase of the sound wave, not by using different tones. A PSK31 signal just sounds like a single tone or note with a slight warble and is used for real-time keyboard-to-keyboard informal text “chats” over the air. It works very well with low power levels and for this reason it has become a favorite for QRP and stealth antenna operators.

PSK31 was developed by Peter Martinez (G3PLX) and introduced to the amateur radio community in late 1998. PSK31 can often overcome interference and poor propagation conditions in situations where voice or other data methods of communication fail. Contacts can be conducted at less than 100Hz separation, so with disciplined operation at least 20 simultaneous PSK31 contacts can be carried out side-by-side in the bandwidth required for just one SSB voice contact.

Typically, you can make good round-the-world PSK31 contacts with 10-25W.

So what do you need to work PSK31? First, you need a transceiver capable of working on single side band (SSB) – you’ll actually be using upper side band (USB).

Next you will need some software, such as FLDIGI, Digipan or WinPSK – most of the packages are free. (See the digital page here on the kb9at.com site for software download links.)

Lastly, you’ll need a data interface and cables to connect your computer to your transceiver. You can build your own or buy one ready made. (The Signalink USB device works great here at kb9at for virtually all digital modes and does not tie up your computer's sound card.) The signals from your computer are fed via the interface to either the radio’s microphone jack or an auxiliary connection into the transceiver.

HF PSK31 Frequencies: Transmit Frequency using USB (Upper Side Band) Modulation.) Fine tune using PC's mouse via the computer's waterfall display.