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Receiving and Transmitting PSK31 With Your Macintosh


Using MultiMode, you can send and receive PSK31 with your Macintosh. After connecting your Mac to your radio (see our interfacing notes for details on this), fire up your copy of MultiMode and set it for PSK31 mode.

Next, tune in a station sending PSK31. For example, on 20 meters, 14070 is the most active PSK31 frequency, tune it in any time the band is open, and you are almost sure to hear several PSK31 stations active. Set your receiver mode for USB.

The above display shows the PSK31 tuning indicator in MultiMode. The audio spectrum from 600 to 2200 Hz is displayed, along with the intensity of the audio at each frequency. This lets a large number of PSK31 transmissions be identified at the same time. To select a particular transmission, the center frequency of MultiMode needs to be set equal to the center frequency of the transmission. This could be done by typing into the Center frequency setting, but an easier way is to just click on the center of the transmission. A red marker is set, showing the center frequency. In this case, 1487 Hz (which is also displayed in the Center frequency text entry box for your reference). The + and - buttons allow the center frequency to be incremented or decremented in 1 Hz steps.

When properly tuned in, decoded text will start to appear in the text area of the MultiMode window.

For transmitting PSK31, your Mac produces audio as set by the center frequency. When you start transmit mode, using cmd-T, MultiMode will begin playing the PSK31 audio. You can feed this into your transceiver's microphone input to transmit PSK31. It's that easy!

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Chris Smolinski