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 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 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 low noise analog filter with adjustable filter frequency includes an oscillatory circuit, whose resonance frequency equals the filter frequency of the filter. The oscillatory circuit has a first circuit branch. One of the frequency determining elements is a capacitance and the other an inductance. The low noise analog filter further includes an amplifier with adjustable amplification installed in one of the two circuit branches. The output of the amplifier is connected with its inverting input via the frequency determining element arranged in such circuit branch. In filter operation, the amplifier amplifies, according to the adjusted amplification, a voltage applied across the frequency determining element arranged in such circuit branch and thereby effects a corresponding change of an electrical current flowing through such frequency determining element.

Abstract: A low noise analog filter with adjustable filter frequency includes an oscillatory circuit, whose resonance frequency equals the filter frequency of the filter. The oscillatory circuit has a first circuit branch. One of the frequency determining elements is a capacitance and the other an inductance. The low noise analog filter further includes an amplifier with adjustable amplification installed in one of the two circuit branches. The output of the amplifier is connected with its inverting input via the frequency determining element arranged in such circuit branch. In filter operation, the amplifier amplifies, according to the adjusted amplification, a voltage applied across the frequency determining element arranged in such circuit branch and thereby effects a corresponding change of an electrical current flowing through such frequency determining element.