Most non-voice radio transmissions use some form of tone encoding; this includes FAX, RTTY, SSTV, and many more. A simple audio cable from the radio to the audio input of my macbook pro (just off to the right, but not visible), plus the right software, lets me easily decode and display these transmissions. The Internet has taken on the role of sending a great deal of this information, and so interesting transmissions are becoming more difficult to find, but they're still out there, particularly being sent out of the developing countries.

The monitor above the radio is plugged into the rectangular unit in between the speaker and the radio; this is the DMU, or "Data Management Unit", a tool that lets you see the RF spectrum directly, as shown here, as well as keep logs, aim your antenna, examine the spectrum of received and transmitted audio, keep various world clocks and other hand radio-related activities. The DMU is a Linux based computer that monitors a special interface card in the radio. The memory card visible in the front of the DMU actually contains the boot software and also my personal settings, such as memory channels, my location, and so forth.

#radio

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