Jr. Barnum et Ee. Simpson, OVER-THE-HORIZON RADAR TARGET REGISTRATION IMPROVEMENT BY TERRAIN FEATURE LOCALIZATION, Radio science, 33(4), 1998, pp. 1077-1093
This paper addresses the problem of over-the-horizon radar (OTHR) targ
et position registration in the presence of ill-defined ionospheric st
ructures. At present, OTHR is subject to frequent position uncertainti
es due to ionospheric abnormalities, such as tilts and ambiguous multi
path propagation modes, that are difficult to model adequately during
radar operation. The detection and registration of discrete terrain fe
atures in parallel with routine radar operations were studied with the
goal of significantly reducing radar target position errors under mos
t circumstances. The Wide Aperture Research Facility (WARF) experiment
al OTH radar testbed was modified to enable the automatic detection, p
rocessing, display, and registration of terrain features and HF repeat
er (beacon) echoes in parallel with aircraft detection and tracking op
erations. Many distinct terrain feature locations were studied in sign
ificant detail, including cities, mountain peaks, and an island, and t
he automatically determined position correction offsets were statistic
ally compared with collocated beacons that served as ground truth. It
was found that 100% of the offsets had expected errors of less than 5.
7 nautical miles (1 nautical mile equals 1.852 km); and 93% of the off
sets (with better ionospheric propagation) had expected errors of less
than 3.2 nautical miles. We conclude from the research that terrain f
eatures can be used to provide coordinate registration benchmarks over
an OTHR coverage area in the same way that beacons can be used.