Transatlantic Radio Telephone Transmission

The paper reports upon measurements of trans-Atlantic radio transmission which had been made during the past two years in a study of the possibilities of trans-Atlantic radio telephony. These measurements cover several different frequencies in the range below 60 kilocycles in both directions across the Atlantic and represent probably the most comprehensive study yet made of any transmission path. An earlier paper described the special high-power radio telephone system and the measurement methods employed in the tests, and gave certain preliminary measurement results. The relation which exists between the diurnal and seasonal variations of signal field and the exposure of the transmission path to sunlight is shown. The conformity of the measured results to the values determined by formulas is indicated. Interesting correlation is shown between abnormal radio transmission and magnetic storms. The diurnal and seasonal characteristics of noise are shown to be generally similar to those of signal strength and indicate the noise to be of tropical origin. The average frequency distribution of static is shown for various receiving stations. Signal-to-noise ratios are shown for both England and United States for transmission on 50 odd kilocycles, together with the improvement afforded by a directional receiving system of the wave-antenna type.