GB190704711A - A Method of Determining Position of Vessels at Sea and Apparatus therefor. - Google Patents

Abstract

4711. Fessenden, R. A. Feb. 26. Bearings and courses, determining. -The position of a vessel at sea is determined by the estimation of the intensities of the signals received from one or more of a series of shore stations A, B, C, either relatively or absolutely but preferably relatively to each other, and in some cases relatively also to signals of fixed strength from a standardizing- apparatus on the vessel. The station C sends by clock - work at predetermined intervals suitable signals 1 ... 7, preferably varied in intensity so that each signal shall produce the same intensity at say twenty miles farther out than the preceding signal. Similarly the stations B, A sends signals 8 ... 14 and 15 ... 21, respectively, which may be of different group frequency but preferably are of the same frequency and vary in intensity in the same way as those from station C; all the signals are sent at non-interfering time intervals. A vessel at E and bound for the port D just receives the signal 21 of standard strength. This would indicate the distance but not the direction, provided the apparatus was in good order. At the point F, signals 13, 19 will each be of equal intensity with the standardizing-signal, which determines distance and direction. Without the standardizing - apparatus, the direction only would be determined. At the point G, of the signals 5, 10, 20 received of equal intensity with each other or with the standard, the signals 10, 20 give the direction and distance from A and B, and the signal 5 from C serves to check the result, with or without the use of the standardizing-apparatus. The seven signals may be sent simultaneously but with different group frequencies. A suitable standardizing-apparatus is shown in Fig. 2, where an antenna 22 is connected through a transformer 24, 25 with a detector 28, telephone 29, and potentiometer 30. Another transformer 26, 27 is connected through a capacity 31 and variable inductance 37 with a commutator 32 driven by a motor 35, and a potentiometer 30<1> having a movable contact 36 of which the positions correspond with standard signals. The commutator charges the capacity 31 and discharges it through the coil 27, an impulse being transmitted through coils 26, 24, 25 to the telephone 29. By using the variable inductance 37 and keeping the capacity 31 constant, the energy in each discharge is not altered by the change in frequency.