Smart guided wave radar transmitter for continuous level measurement and overspill protection. Levelflex FMP45 high pressure/high temperature version provides automatic gas phase compensation as a unique and most accurate solution to compensate for changing radar signal speeds and thus, large measuring errors that can occur due to high temperatures and high pressures, especially in polar gases/steam, e.g. boiler drum. Levelflex sees the error in the application and updates the output reading to the highest accuracy every second. Thus, Levelflex provides peace of mind and confidence in the accuracy of the level measurement, even in temperatures of -200°C...+400°C/ -328°F...+752°F and pressures of vacuum to 400 bar / 5800 psi.