1967

Eavesdropping On Silence

Norine Allen of Ottawa listens to what cannot be heard, at a distance of from 55 to 250 miles. Give up?

She is Canada's only female in a small group of Telecommunications and Electronics Branch technicians who take soundings of the ionosphere, a layer of ionized particles which blanket the earth and, among other things, permit long-distance radio broadcasts.

Knowledge of conditions current in the ionosphere is important for the efficient operation of communications with ships, aircraft, lighthouses-with all of which D.O.T. has responsibilities - and, indeed, almost every kind of radio communication.

This strange, invisible sphere is in a state of continual change. In sunlight it gradually spreads into three layers. The inner one about 55 miles high, the outer extending to some 250 miles. As night falls, the upper and lower strata gradually converge until a single layer results. Sun spots, among other factors, have a marked effect on the behaviour of the ionosphere.

Radio waves, generally, are deflected from the ionosphere back down to earth, thus enabling a radio message to travel as far as 2,000 miles or more. Much depends on the wavelength, however, for under certain circumstances some frequencies are absorbed into the ionosphere wholly or partially, resulting in a weak signal or none at all.

This is where Norine and her ionosonde come in. Every 15 minutes the ionosonde, like 50 others in various parts of the world, sends a series of electronic pulses straight into the ionosphere. The electronic "echoes" are recorded on film which, when developed, Norine puts in a projector to "scale", taking off certain information to put on a graph and code into digital form. The information includes the height of the ionosphere and its reaction to different electronic frequencies. Analysis of such specific properties of the ionosphere, as reported by an extensive network of ionosondes, permits forecasts of conditions for a week or 10 days. This enables short-wave stations to choose, from among the frequencies allotted to them, the ones which will get the best bounce, or "skip", from the ionized ceiling.

The Department maintains five "sounding" stations. Located at approximately 47 degrees of latitude are Kenora, Ottawa and St. John's, Newfoundland. Kenora also is in line perpendicularly with stations at Resolute and Churchill, on the ninety-fifth meridian.

Norine and other technicians of the Ottawa Station which is under the administration of Ottawa Telecommunications Area Manager and is part of Toronto Region's Maintenance and Operations Division, Telecommunications and Electronics Branch, have a unique double responsibility.

Results are sent to the maintenance and operations division branch headquarters, which sends daily reports to Fort Belvoire, Virginia, the world warning centre for geophysical phenomena. Reports also are sent to the centre of the American ionospheric group at Boulder, Colorado.

Like most of this select group of technicians, Norine has had extensive radio experience. She first worked for D.O.T. in 1944 at the Winnipeg monitoring station. This was followed by three years as a radio operator for the Canadian army.

Next came permanent employment as wife of Warrant Officer Ted Allen of the Royal Canadian Corps of Signals which has involved over two years at Yellowknife, N.W.T., and postings to Edmonton and Ottawa. They have two children - Patricia, 18, and Garth, 10.

In Edmonton Norine went back to radio work, serving the Department of National Defence's Northwest Territories and Yukon radio system. She rejoined D.O.T. about a year ago.