Measuring system having a measuring transducer of vibration-type

A measuring system for flowing media in pipeline, the measuring system comprising:

• a measuring transducer of a vibration-type configured to enable a medium to flow therethrough during operation and configured to generate oscillation signals corresponding to media parameters of the flowing medium, the measuring transducer comprising:
• at least one measuring tube extending with an oscillatory length between an inlet-side, first end and an outlet-side, second end, the at least one measuring tube adapted to convey the flowing medium and having a plurality of natural oscillation modes;
• at least one oscillation exciter configured to convert electrical, excitation power into vibrations of the at least one measuring tube;
• and
• at least one oscillation sensor configured to register vibrations of the at least one measuring tube and to generate an oscillation signal of the measuring transducer representing the vibrations of the at least one measuring tube;
• and
• transmitter electronics electrically coupled with the measuring transducer and configured to activate the measuring transducer and to evaluate the oscillation signals received from the measuring transducer, the transmitter electronics further configured to deliver a driver signal to the at least one oscillation exciter, thereby feeding electrical, excitation power into the at least one oscillation exciter as to effect vibrations of the at least one measuring tube such that:
• the driver signal has, at least at times, a first type of driver signal, which is a sinusoidal signal component with a signal frequency corresponding to an instantaneous eigenfrequency of a natural mode of oscillation of a first order of the at least one measuring tube, in which is present a first oscillation node at the first end, a second oscillation node at the second end, and, in the region of the oscillatory length, exactly one oscillatory antinode, whereby:
• the at least one measuring tube, excited by the at least one oscillation exciter, is driven to perform, at least partially, resonance oscillations corresponding to the instantaneous eigenfrequency of the mode of oscillation of the first order;
• and
• the oscillation signal includes a first type of oscillation signal, which is a sinusoidal signal component with a signal frequency corresponding to the signal frequency of the first type of driver signal, and
• the driver signal includes, at least at times, a second type of driver signal, which is a sinusoidal signal component with a signal frequency that deviates from an instantaneous eigenfrequency of any natural mode of oscillation of the at least one measuring tube, in each case, by at least one of:
• more than 1 Hz, and more than 1% of the eigenfrequency of the respective natural mode, whereby:
• the at least one measuring tube, excited by said at least one oscillation exciter, is driven to perform, at least partially, forced oscillations outside of resonance;
• and
• the oscillation signal includes a second type of oscillation signal, which is a sinusoidal signal component with a signal frequency corresponding to the signal frequency of the second type of driver signal,
• wherein the transmitter electronics is configured to set the signal frequency of the second type of driver signal such that said signal frequency is in a predetermined frequency ratio to either the instantaneous eigenfrequency of the mode of oscillation of the first order or the instantaneous signal frequency of the first type of driver signal,
• wherein the signal frequency of the second type of driver signal is set as a function of at least one of:
• the first type of driver signal;
• and
• the first type of oscillation signal,
• wherein the transmitter electronics is further configured to diagnostically detect whether or to what extent the measuring system, in comparison to a reference state determined earlier therefor, is changed such that a system parameter measured value for at least one system parameter deviates from a system parameter reference value for the at least one system parameter by more than a predetermined measure of tolerance, wherein the at least one system parameter characterizes the measuring system and is determined during ongoing measurement operation of the measuring system, and wherein the system parameter reference value is determined in the reference state of the measuring system,
• wherein the system parameter measured value is based on the signal component of the second type of driver signal, which signal and the signal component of the second type of oscillation signal, wherein the signal component of the second type of driver signal is an electrical current flowing through the at least one oscillation exciter (Idry,II) or is a voltage driving said current (Udrv,II), and wherein the signal component of the second type of oscillation signal is an amplitude of a voltage generated by the at least one oscillation sensor (Usens1,II), and
• wherein the system parameter measured value is defined by a ratio:
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