Evaluation of an echo shape of filling level sensors
A transit-time fill-level measuring device for measuring the fill level of a filling material in a container is stated, in which transit-time fill-level measuring device information about the topography of the filling material surface is determined on the basis of the shape of a single echo curve of the receiving signal. From this the fill volume can then be derived.
1. A fill-level measuring device for measuring the fill level of a filling material in a container, comprising:
a receiver receiving a receiving signal reflected by the filling material surface; and
a computing unit determining information about the topography of the filling material surface as a function of a shape of the receiving signal;
wherein the computing unit determines on the basis of the shape of an echo if there is a charge cone, a discharge funnel or an irregular surface of the filling material,
wherein the measuring device is configured for deriving a form factor from the shape of the echo, and
wherein a determination from the form factor of a distance value s, which represents the fill volume, from the sensor to the filling material surface, is performed,
wherein the decision as to whether a discharge funnel or a charge cone is present is derived from the shape of the echo by a comparison of the position of a maximum within the echo with the position of the echo beginning A and the position of the echo end E,
wherein, if the maximum is close to the left side of the echo, the computing unit decides that there is a charge cone, and
wherein, if the maximum is close to the right side of the echo, the computing unit decides that there is a discharge funnel.
2. A fill-level measuring device for measuring the fill level of a filling material in a container, comprising:
a receiver receiving a receiving signal reflected by the filling material surface; and
a computing unit determining information about the topography of the filling material surface as a function of a shape of the receiving signal;
wherein the computing unit determines on the basis of the shape of an echo if there is a charge cone, a discharge funnel or an irregular surface of the filling material,
wherein the measuring device is configured for deriving a form factor from the shape of the echo, and
wherein a determination from the form factor of a distance value s, which represents the fill volume, from the sensor to the filling material surface, is performed,
wherein the distance value s is determined according to the following formula:
s
=
A
+
1
3
*
h
*
(
1
+
f
)
wherein:
s=distance between the sensor and an assumed flat filling material surface;
A=distance between the sensor and the beginning of the echo from the filling material;
h=height of the filling material surface, determined from the length of the echo band, i.e. the distance between the echo beginning and the echo end; and
f=form factor relating to the echo, wherein a value of the form factor is at most 1.
3. The fill-level measuring device of claim 2 ,
wherein the value of the form factor is: (a) 1 in the case of a charge cone, and (b) 0.5 in case of a flat surface.
4. The fill-level measuring device of claim 1 ,
wherein the value of the form factor is: (a) 1 in the case of a charge cone, and (b) 0.5 in the case of a flat surface.