PSK31 was developed by an  English amateur radio operator Peter Martinez (G3PLX) and introduced to the wider amateur radio community in December 1998. Martinez initially called his creation varicode, because it uses variable length encodings Huffman codes to represent characters.

PSK31 was enthusiastically received, and has since quickly spread into worldwide use. Due to the efficiency of the mode, it has become especially popular with operators whose circumstances do not permit the erection of large antenna systems and/or the use of high power.

Because the mode is seen as such an effective means to communication via PC, its audience has grown like wildfire in the years since its release and lent a new tone to the on-air conduct of digital communications.

 Setup checklist

    Setup checklist to minimise distortion & excessive bandwidth of PSK signals

    1 Tune the rig for normal output on CW
 

    2 Change to the appropriate sideband setting (USB for PSK is standard)
 

    3 Turn off the speech processor and leave it off
 

    4 Set the audio control of the rig as you would for normal SSB operation
 

    5 Set the PSK software to Transmit, with no data being transmitted
 

    6 Adjust the audio output from the soundcard so that the RF power output from the rig is no more than 25% of

       the cw output.  ( 25 watts for a 100 watt rig)  There should be no ALC indication at this power level.

       Although you might be able to set the power higher with no ALC, this setup should ensure that a very            

       clean signal is transmitted.

 

A few words of caution. If driving the microphone input of the rig, an attenuator between the soundcard output and the transceiver input may be needed.