Time delay variations in HF propagation


  • R. W. LaBahn,

  • R. B. Rose


An experiment has been established to determine the range of environmentally induced fluctuations in the propagation of HF radio signals. Data are collected with a fully digitized system that is stablized with a cesium beam standard. Initial efforts have been directed toward monitoring at San Diego, California, the time of arrival of WWV transmissions from Fort Collins, Colorado, for the frequencies 5, 10, 15, and 20 MHz. Variations in these arrival times from 25 to 175 μs have been observed depending upon frequency, mode of propagation, time of day, and solar activity.