Comparison of C-2 Ionospheric Sounder Data With Frequency Predictions for Short-Range Communication With Man-Pack Transceivers in Thailand
Abstract
The report briefly discusses several ionospheric parameter prediction techniques and compares values of f sub o F2, 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 o F2, 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 o F2 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 AN/PRC-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 o F2 and f sub min scaled from the data from the modified C-2 sounder at Bangkok. Communication failure in the early morning hours during sunspot minimum is shown to be critically dependent on the lower tuning limit of the set. The parameter f sub o F2 is extrapolated to the next sunspot maximum period to help estimate the design range for man-pack radios.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1966
- Accession Number
- AD0662065
Entities
People
- Clifford L. Rufenach
- George H. Hagn
Organizations
- SRI International