. Discovery. Science. tion of T, but if similar observations are made at a second station not in the same straight line as TR, the data are then sufficient to determine the exact position of T. Thus the position of the unknown wireless station X (Fig. 3) can be determined from observations made at two fixed stations Y and Z (Fig. 3). Mhen X transmits, Y and Z, by means of their direction- finding apparatus, read off the magnetic bearing to the unknown station as determined by the position of the rotating coil when signals from X are loudest. The point of intersection of these two bearings give
. Discovery. Science. tion of T, but if similar observations are made at a second station not in the same straight line as TR, the data are then sufficient to determine the exact position of T. Thus the position of the unknown wireless station X (Fig. 3) can be determined from observations made at two fixed stations Y and Z (Fig. 3). Mhen X transmits, Y and Z, by means of their direction- finding apparatus, read off the magnetic bearing to the unknown station as determined by the position of the rotating coil when signals from X are loudest. The point of intersection of these two bearings gives the position of X. Stations Y and Z are, of course, in communication with each other, either by wireless or by land-hne. It may here be remarked inciden- tally that by such means the position of enemy sub- marines, ships, headquarters, etc., using wireless during the war were determined. With certain modifications and adjustments, the above principle has been successfully applied to air- craft, and at least two main methods are in use. In the first of these the aircraft carries the direction-finding wireless apparatus. To find his position at any time, the aircraft operator selects two land stations whose positions he knows accurately. \\'hen these stations transmit, he takes a bearing to each of them by means of his direction-finding apparatus. These two read- ings (which only take a matter of some seconds) are sufficient to enable him to plot his position accurately on the map. A check can be obtained by taking the bearing to a third station. This method is of great. value, especially during war, as the aircraft can deter- mine its position without transmitting and thus re- vealing its own presence. It also makes flying possible on cloudy nights when landmarks cannot be seen. The stations to which bearings are taken should obviously not be too close together. During peace-time, and also during war-time, there are always sufficient high-power wireless stations (such as Poldh
Size: 2057px × 1214px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcontribu, booksponsoruniversityoftoronto, booksubjectscience
