HF Digital Modes
I am very interested in the HF digital modes. I've started off with PSK-31, but I intend to branch out into RTTY and AMTOR. I started with PSK-31 because all you need is a sound card interface, a computer and some software. I already had the computer and I acquired the soundcard interface to do SSTV so this was not a big stretch. I've just acquired a PK-232 TNC so I hope to try AMTOR soon. I've played around with RTTY a little but I've had no success so far. I am still learning the software and techniques.
PSK-31 is a non error correcting keyboard to keyboard digital mode. It performs well and takes up very little room on the spectrum. (31.5 Hz to be precise) There are several programs available (many of them freeware) to do PSK-31. The software I use is Digipan which is shareware. Go here to get it Digipan Download. Digipan like most of the PSK-31 programs uses a waterfall display to show the signals. Operating it is easy. The signals appear as yellow lines "falling" down the screen. Simply click on one of the lines and the plain text appears in the upper window. The "thickness" of the yellow line indicates the signal strength. The selected signal in the example is very strong (it was from a ham just down the street). You can see weaker signals to the right of the selected signal. It's quite amazing how well this mode works with weak signals.
A screen shot of Digipan showing psk reception on 20 Meters
To transmit, press the T/R button and the transmitter will key up. Whatever you type in the lower box is transmitted in the PSK-31 format. To make routine text (such as callsigns and CQs) easier to send, the program has a macro feature. Pressing one of the buttons at the top of the screen will type the programmed text in the sending box. If you right click the button, you can set the typed text for that macro button.
Where to find PSK-31 Activity:
Most PSK-31 activity is on 20 Meters at 14.070 MHz or on 10 Meters at 28.120 MHz. You will also find it at 24.914 MHz, 21.070 MHz, 18.109 MHz, 10.139 MHz, 7.070 MHz, and 3.580 MHz. Some of the nicest conversations I've had on this mode were on 12 Meters and 30 Meters. There is also activity on 6 Meters and 2 Meters in the SSB portion of the band.
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Copyright 2002 Page last modified December 18, 2002