Measurement of Best Time-Delay Resolution Obtainable Along East-West and North-South Ionospheric Paths


  • J. T. Lynch,

  • R. B. Fenwick,

  • O. G. Villard Jr.


A high-resolution, frequency-modulated, continuous-wave (FMCW), oblique-incidence sounder was used to measure the minimum equivalent pulse widths that could be transmitted over two different oblique paths. One path, 1880 km long, was substantially an east-west path from Lubbock, Texas, to Stanford, California. The second path, 1300 km long, from Bozeman, Montana, to Stanford had characteristics representative of north-south propagation. The data from each path indicated that for 50% of the daylight hours, pulse widths as small as 3 to 5 μsec could be transmitted without significant ionospheric broadening if the minimum dispersion frequency was used.