초록 ▼

A level measuring device using microwaves comprises an antenna for sending transmitted waves toward the surface of a material whose level is to be measured, and for the reception of echo waves resulting from reflection at the surface, and a receiving and evaluating circuit which derives from the ech

A level measuring device using microwaves comprises an antenna for sending transmitted waves toward the surface of a material whose level is to be measured, and for the reception of echo waves resulting from reflection at the surface, and a receiving and evaluating circuit which derives from the echo waves received by the antenna an echo function representative of the echo amplitudes as a function of the distance and determines from the echo function the transit time of the microwaves from the antenna to the surface of the material and therefrom the distance of the surface of the material from the antenna. In order to detect the formation of deposits of the material on the antenna or further trouble conditions, such as damage to the antenna or the loss thereof, the level measuring device comprises an arrangement which compares a section of the echo function originating from a reference reflection point in the antenna or in the vicinity of the antenna with a predetermined threshold value and produces a signal indicating the existence of a state above or below the said threshold value. The reference reflection point may be constituted by a part of the antenna or a separate reference reflector mounted in the antenna or in the vicinity thereof.

대표청구항 ▼

A level measuring device using microwaves comprising an antenna for sending transmitted waves toward the surface of a material whose level is to be measured and for receiving echo waves resulting from reflection of the transmitted waves at the surface, a receiving and evaluating circuit adapted to d

A level measuring device using microwaves comprising an antenna for sending transmitted waves toward the surface of a material whose level is to be measured and for receiving echo waves resulting from reflection of the transmitted waves at the surface, a receiving and evaluating circuit adapted to derive from the echo waves received by the antenna an echo function representative of the echo amplitudes as a function of the distance between the antenna and the surface of the material and to determine from the echo function the transit time of the microwaves from the antenna to the surface of the material and therefrom the distance of the surface of the material from the antenna, a reference reflection point situated in at least one of the antenna and the vicinity of the antenna, and an arrangement for comparing a section of the echo function originating from said reference reflection point with a predetermined threshold value in order to detect a condition of the antenna.