Talking by Meteor

When a meteor--even if it is no bigger than a grain of sand--hits the earth's atmosphere, it leaves a long trail of ionized particles 60 miles up. Radio communications men have known for years that these trails act as wave reflectors, and they have tried to use them to make certain very short waves, which normally stop at the horizon, carry messages far around the curve of the earth. Chief difficulty was that most of the ionized trails last only a second or so. Before one of them could be located and used as a reflector, it was usually too weak to be useful.

Last week the Canadian government declassified a system which puts the meteor trails to work. Called "Janet" and developed by a group led by Dr. P. A. Forsyth, the system comprises two ground stations as much as 1,000 miles apart which constitute a "circuit." Their beam antennae look toward each other. When a meteor hits in the right place between them and leaves its reflecting trail, a signal from the receiving station reaches the transmitting station and tells it to send its message.

Several hundred usable meteor trails are formed per hour, but since each trail can be used for only one second, the transmitter has to send its message fast. This it does by an electronic mechanism which stores the message and sends it in a "burst" less than one second long. The receiving station has an apparatus that stores the burst and plays it out slowly as an understandable message.

The Janet system may be specially valuable for far-northern Canada. There ordinary radio communications are often fouled up by atmospheric irregularities connected with the northern lights, but signals reflected from meteor trails are largely unaffected. First chance at the new apparatus will go to Canada's armed services and to those of her allies. Civilians may get theirs later.

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