Abstract: Disclosed is a method for a radar-based fill level measurement according to the pulse transit time method. Also disclosed a fill level measuring device for carrying out said method. On the basis of an evaluation signal, the relation between the clock rate and the sampling rate, and a predefined target relation, an evaluation curve is generated. The fill level is thereby determined on the basis of said evaluation curve. The evaluation curve is generated by means of temporal expansion or compression of the evaluation signal, wherein the compression or the expansion is carried out as a function of a ratio between the measured relation and the target relation. Any deviation of the sampling rate from the setpoint value of the sampling rate, for example due to faulty control, is compensated. Thus, the potentially attainable accuracy of the fill level measurement is increased due to the invention.

Abstract: Disclosed is a transmitting device comprising two galvanically isolated sub-circuits. The first sub-circuit comprises: a carrier signal source for outputting a carrier signal; a digital signal source for outputting binary signal levels; and a logic component for performing an AND operation on two input signals. The second sub-circuit comprises: a signal input; a signal output; and a first RC element, the signal input, the signal output and the RC element being connected in parallel to one another with respect to a second reference potential. A first isolating capacitor is connected between the first logic output and the signal input for galvanic isolation. A second isolating capacitor is connected between the first reference potential and the second reference potential for galvanic isolation.

Abstract: An FMCW-radar based distance measuring device is characterized in that, in addition to analogue high-pass and low-pass filtering, the evaluation signal typical for FMCW additionally undergoes subsequent digital filtering. In this case, the analogue/digital conversion takes place by oversampling. As a result, according to the invention, all those frequencies in the evaluation signal that are above or below the frequency corresponding to the distance of the object are effectively suppressed. At the same time, the analogue filters can be constructed with a very low level of complexity. The space requirement and the costs of the analogue components is reduced thereby. In addition, the dependence on temperature of the distance measuring device is reduced thereby. The potentially high distance resolution is also maintained.

Abstract: Disclosed is a method for determining the serviceability of a fill-level measuring device that includes at least one electronic unit. The method can be applied to any type of field device that includes at least one electronic unit supplied by an energy store of the field device. The method includes: measuring the capacitance of the energy store and/or measuring the power withdrawal at the energy store. The field device is classified as not operationally reliable if the capacitance of the energy store is below a defined minimum capacitance and/or if the power withdrawal deviates from a predefined normal consumption. An advantage of the method according to the invention is that, in addition to the functional diagnosis, in particular also a prediction up to the expected elapsing of the remaining operating time can be created by recording the power withdrawal or the capacitance over progressive measurement cycles.

Abstract: Disclosed is a transmitting device comprising two galvanically isolated sub-circuits. The first sub-circuit comprises: a carrier signal source for outputting a carrier signal; a digital signal source for outputting binary signal levels; and a logic component for performing an AND operation on two input signals. The second sub-circuit comprises: a signal input; a signal output; and a first RC element, the signal input, the signal output and the RC element being connected in parallel to one another with respect to a second reference potential. A first isolating capacitor is connected between the first logic output and the signal input for galvanic isolation. A second isolating capacitor is connected between the first reference potential and the second reference potential for galvanic isolation.

Abstract: Disclosed is a method for a radar-based fill level measurement according to the pulse transit time method. Also disclosed a fill level measuring device for carrying out said method. On the basis of an evaluation signal, the relation between the clock rate and the sampling rate, and a predefined target relation, an evaluation curve is generated. The fill level is thereby determined on the basis of said evaluation curve. The evaluation curve is generated by means of temporal expansion or compression of the evaluation signal, wherein the compression or the expansion is carried out as a function of a ratio between the measured relation and the target relation. Any deviation of the sampling rate from the setpoint value of the sampling rate, for example due to faulty control, is compensated. Thus, the potentially attainable accuracy of the fill level measurement is increased due to the invention.

Abstract: Disclosed are methods for checking the operational reliability of a radar-based fill level measurement device, which operates according to the pulse time-of-flight method. The methods include detecting controlled variables of the fill level measurement device, such as the signal amplification or the sampling rate. By comparing the controlled variable with a corresponding limit value, it can be determined whether the fill level measurement device is operationally reliable or whether the operational reliability of the fill level measurement device has been lost with increasing operating times because of the degradation of electrical components. It is also advantageous that, on the basis of the methods according to the invention, it is possible to make a prediction according to the principle of “predictive maintenance” regarding how much remaining operating time is estimated to be left until a possible functional failure of the fill level measurement device.

Abstract: A method for checking the functional ability of an FMCW-based fill-level measuring device, which serves for measuring the fill level of a fill substance located in a container, as well as to a fill-level measuring device suitable for performing this method. For checking the functional ability, a microwave signal is produced, whose frequency change differs from the frequency change of the measurement signal used during regular measurement operation. By comparing the frequency of the difference signal resulting from the microwave signal with a predetermined reference frequency, it is ascertained, whether the fill-level measuring device is functionally able. Thus, the fill-level measuring device detects, independently, whether it is functionally able, or whether an error is present, caused principally by device-internal disturbance signals. This offers, especially, a clear advantage as regards meeting safety standards for the field device.

Abstract: A method for checking the functional ability of an FMCW-based fill-level measuring device, which serves for measuring the fill level of a fill substance located in a container, as well as to a fill-level measuring device suitable for performing this method. For checking the functional ability, a microwave signal is produced, whose frequency change differs from the frequency change of the measurement signal used during regular measurement operation. By comparing the frequency of the difference signal resulting from the microwave signal with a predetermined reference frequency, it is ascertained, whether the fill-level measuring device is functionally able. Thus, the fill-level measuring device detects, independently, whether it is functionally able, or whether an error is present, caused principally by device-internal disturbance signals. This offers, especially, a clear advantage as regards meeting safety standards for the field device.