Club Meeting

PSK31 is one of the "new" digital modes which are highly developed because of computer/sound card technology. PSK31 has become the most popular digital mode for live conversation. "PSK" stands for "phase shift keying" in which the modulation method is a change in polarity, as distinct from RTTY and others which use frequency shift keying. "31" stands for a baud rate of 31.25. Using polarity shifts makes it possible to use a narrower bandwidth than is seen in the average CW transmission. Thus PSK31 can cut through static and work weak signals.

Peter Martinez, G3PLX, wrote a "Varicode" coding system, which he considered an extension of Morse Code, for PSK31. He wrote the first popular PSK31 software program, also called PSK31. An interface is needed between the computer and radio to do PSK31. The interface consists of a potentiometer and an isolator. Various brands and types of interfaces were discussed. The Rigblaster is the most popular interface (even though it is the most expensive) because it is easy to hook up and easy to use.

Currently, Digipan is the most popular software program for PSK31. The Digipan program, hooked to HF with a Rigblaster, was projected onto the classroom screen and some of Digipan's features were pointed out. The "waterfall" feature shows, at a glance, the stations which are transmitting. The stations' signals show up as vertical yellow bars which scroll downward on the waterfall. It can be seen which stations are strong and which are weak by how well they show up against the background. The diamond-shaped cursor, when positioned over a station, causes the text from the ongoing QSO or CQ to be printed on the screen. A CQ can be done by clicking in an area of the waterfall which has no signal activity and then transmitting CQ from that frequency. There is a write-ahead feature so that text can be written while the other person is transmitting, to be transmitted in turn. Macros make it easy to enter often-used phrases and sentences.

A CQ was put out and answered by a station which had a very weak signal. The signal faded and returned. Then another station transmitted close enough to overlap the first station and caused the first station's transmission (and our QSO) to be lost.

Some advantages and disadvantages of PSK31, compared to phone, were given, as well as some experiences with PSK31 QSOs. Operating tips were given; most importantly, to keep power LOW so as not to overdrive the audio and take up bandwidth space which could otherwise hold several (or many) signals. Another tip is to watch the waterfall before transmitting in order to avoid coming in on other people's QSOs; an empty space may be the pause between transmissions in a QSO. Also, wait awhile after doing (or answering) a CQ, in order to give another station sufficient opportunity to respond.

Computer requirements for Digipan were discussed. A bibliography in the handout gives references and URLs for articles which are good summaries of PSK31 and/or which give many links to other URLs dealing with PSK31.

For an e-mail copy of the PSK31 handout, which includes clickable URLs for links to PSK31 information, please send a request for it to Orcy at lyle@brainerd.net . The e-mail copy will include some URLs which were not in the paper copy. If anyone has questions about PSK31, feel free to contact Orcy (e-mail or 828-0351) who will try to answer the questions.