Radio for Aviation

Radio Record, Volume II, Issue 49, 21 June 1929, Page 32

Radio for Aviation

The Latest Invention ANNOUNCEMENT has just been made of the development of a new method, employing a simple radio receiving apparatus utilising a radio broadcast beacon, for detecting speed and location of a ’plane in its relation to the earth with absolute accuracy irrespective of atmospheric conditions, The present aeroplane speed indicators give the speed of the ship through the air and not in relation to the earth. The method, it is claimed, will overcome the greatest difficulties with which aviation has had to contend to date-that is, dangers of misdirection in storm, fog, and night flying. In addition to giving a pilot his actual ground speed at all times, the employment of the system will enable him to determine his location at all times and the direction and speed of the wind. Requires Two Stations.’ FoR operation the system requires the employment of two or more radio transmitting stations, each operating on the identical frequency of wave-length. For illustration, it is assumed that a ’plane is travelling on a straight line between two broadcasting stations called A and B, and both ‘of which are operating on a frequency of 100,000 cycles. As the "plane approaches station A the radio receiving set installed in the plane will record the fixed broadcasting frequency, plus the additional frequencies caused by acceleration as the ‘plane intercepts more waves in the course of its flight toward the broadcasting transmitter. On the other hand, as the ’plane gets further away from station B the frequencies are less and therefore sub-

tracted. It is therefore pointed out that the variations in the frequencies thus indicated on the ’plane’s receiving apparatus will give rise to a beat note; this beat note will thus vary in proportion to the speed of flight, and its indication recorded visually on a dial on the instrument board. Where Direction Varies. WHERE the direction of flight is got. in a straight line between the stations the location of the en stations is indicated by means of an ordinary radio loop-aerial or loopaerial means, and the station is identified by a modulator frequency, which is subsequently filtered out, The angle of flight with respect to both stations being determined, a speed correction can easily be made by the pilot to eliminate error due to deviation of flight direction. Thus the pilot can always locate his position in relation to two known broadcasting stations, his direction of flight and speed of flight. ‘Another advantage which the new system will bring to aviation, it is pointed out, is that the pilot can always utilise the modulator frequencies for receiving messages, in addition to having them serve as a means of iden tifying a broadcasting station. "y t