| CPC G01F 23/288 (2013.01) [G01T 1/17 (2013.01); G01T 1/178 (2013.01)] | 13 Claims |
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1. A radiometric measuring device for determining an intensity of pulses of an interference signal from an external radiation source during a filling level or limit level determination of a filling material in a container, the radiometric measuring device comprising:
detector circuitry configured to receive pulses of a useful signal modulated with a modulation frequency from a gamma emitter and additional pulses of the interference signal from the external radiation source;
averager circuitry configured to output a first count rate of the pulses at an output of the averager circuitry,
wherein the first count rate corresponds to an average of a first number of pulses within a predefined time period received from the detector circuitry over the predefined time period; and
a bandpass system including a bandpass filter having a passband frequency range configured to output a second count rate of the pulses at a bandpass system output,
wherein the passband frequency range of the bandpass filter corresponds to the modulation frequency of the modulated useful signal from the gamma emitter, and
wherein the second count rate corresponds to a second number of pulses within the predefined time period received by the detector circuitry in a bandpass frequency range of the bandpass filter over the predefined time period; and
subtractor circuitry configured to form a differential count rate, wherein the differential count rate corresponds to a difference between the first count rate and the second count rate, such that the differential count rate corresponds to an intensity of the interfering signal from the external radiation source.
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