COMPARISON OF C-2 IONOSPHERIC SOUNDER DATA WITH FREQUENCY PREDICTIONS FOR SHORT-RANGE COMMUNICATION WITH MAN-PACK TRANSCEIVERS IN THAILAND.
STANFORD RESEARCH INST MENLO PARK CALIF
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The report briefly discusses several ionospheric parameter prediction techniques and compares values of f sub oF2, f sub min, and F-layer height h sub L predicted using several of these techniques with observed data taken by the C-2 ionospheric sounder at Bangkok, Thailand from its initial operation in September 1963 through March 1965. The sounder data was used to calculate a correction function for f sub oF2, and corrected predictions are given for April 1965 through December 1966. When the correction functions are used it should be possible to predict the monthly median value of f sub oF2 and f sub min to within about 1.5 MHz for all times of day and the observed values on any given day in the month will be, with probability 0.5, within 2 MHz of the corrected median predictions for all times of day. The effects of anomalous propagation on the predictions are inferred from the C-2 data, and indicate that some account must be made for sporadic E but that spread F and blackout are relatively unimportant during the period of small sunspot numbers. The effect of the lower frequency limit of an HF man-pack radio on communication failure is considered for near-vertical-incidence skywave propagation. The lowest usable frequency calculations for a 15-watt HF man-pack transceiver ANPRC-74 Hughes HC-162 employing horizontal dipole antennas agree very closely with f sub min values calculated from observations with the C-2 sounder. Hence the useful frequency spectrum for this particular HF man-pack transceiver can essentially be approximated by the parameters f sub oF2 and f sub min scaled from the data from the modified C-2 sounder at Bangkok. Author
- Radiofrequency Wave Propagation
- Radio Communications