Over-the-horizon detection process for use by ship to sense other vessels - involves comparison of radar received via ionosphere from distance station with that reflected from local targets

摘要

The process involves using a surface source station (N) to transmit a powerful electromagnetic wave, reflected by the layers of the ionosphere (I) towards a distant region (RS) of the earth's surface. In this region, a vessel (B) compares the radiation (Ps) coming from surface echoes from other targets within the locality with that coming from the ionosphere (Pi). Pref., the vessel has transmitted a call signal (Sa), which allows the working frequency to be defined. The system may use two neighbouring but different frequencies, in the region of double the call frequency. ADVANTAGE - Excellent compatibility with other electromagnetic devices. Discrete and reduced vulnerability.