Abstract :
An account is given of some experiments conducted with two direction-finding receiving stations taking observations on ship transmitters located at various positions in the North Sea between England and the Continent. Damped waves of length 450 m were employed, as given by the ordinary spark transmitting sets with which the ships were fitted. The results obtained are analysed in detail and the various errors encountered are described. The effect of the various local errors to which a direction-finder is subject is not, however, studied in any detail, the object being rather to examine conditions prevailing across the sea, as compared with those across land. By careful attention to certain details various sources of error present in the earlier experiments were eliminated, with a resultant improvement in the overall accuracy. The general conclusion drawn from the experiments is that when the path of transmission is entirely over sea and in a direction making an appreciable angle with the coast line so as to be free from coastal refraction effects, the accuracy of radio direction-finding is sufficient for many navigation purposes up to ranges approaching 100 miles. Observations taken on various land stations with spark transmitters on wave-lengths of 450 and 600 m show that for greater distances over sea the variable ¿night¿ errors encountered are of a much higher order. When the propagation of the waves is entirely over land the corresponding variations are encountered at shorter distances.
