A comparison of trans-equatorial ionosphere propagation predictions from AMBCOM with measured data

Abstract

This thesis examines radio propagation conditions over trans- equatorial (TE) paths. The study precedes Project PENEX, a field experiment to measure and collect calibrated HF skywave signal strength data for polar, equatorial. and near-vertical incidence propagation paths. PENEX will benchmark the absolute accuracy of the signal-to-noise models in the MEDUSA propagation model now being developed by the Naval Command, Control and Ocean Surveillance Center. Since only minimal information is available about TE paths, a comprehensive review of the published literature on TE experiments was completed, with emphasis oil TE paths between magnetic conjugate points. Data from such paths have revealed the presence of unusual propagation i-nodes which are not predicted by standard propagation programs such as PROPHET, IONCAP, and AMBCOM. The review of the literature revealed that Stanford Research Institute (SRI) published measured data on a TE path between the Pacific islands of Kauai and Rarotonga. A comparison was made between the SRI data and predictions for the same path to assess the usefulness of current prediction programs for TE paths. The SRI AMBCOM program was used for this comparison. As expected, sizeable differences were found between the predicted and measured results, especially during times when unusual propagation modes were present. This suggests that prediction programs should be modified to include the observed TE modes..