The dynamic characteristics of a pressure transmitter are the response characteristics of the output to the input when the sensor measures the dynamic signal. When the sensor measures static signals, the measurement and recording process is not limited by time because it is measured without changing over time. However, a large amount of actual measurement is measured as a dynamic signal that changes with time, and the output of the sensor not only needs to accurately display the measured size,
It also displays the law of the measured change over time, ie the measured waveform. The ability of a sensor to measure dynamic signals is represented by dynamic characteristics.
The main difference between dynamic and static characteristics is that the relationship between output and input in dynamic characteristics is not a fixed value, but a function of time, which varies with the frequency of the input signal.
A sensor with good dynamic characteristics, whose output changes with time will reproduce the change of input quantity with time, that is, they have the same time function. However, except for the ideal case, the output signal of the actual sensor does not have the same time function as the input signal, thereby causing dynamic errors.
In the dynamic measurement, when the measured workpiece size changes periodically, the output value of the liquid level transmitter changes periodically, and the frequency is the same as the former, but the output amplitude and phase change with the frequency. This relationship is called the frequency characteristic. The characteristic that the amplitude of the output signal changes with frequency is called the amplitude-frequency characteristic; the characteristic that the phase of the output signal changes with the frequency is called the phase-frequency characteristic. The frequency corresponding to the amplitude falling to 0.707 times the stable amplitude is called the cutoff frequency.
Since the change of output amplitude and phase may bring difficulties to signal processing (such as subdivision) and measurement error, the sensor selected in dynamic measurement should be compatible with the working frequency string. In the high-precision measurement, the motor used in the transmission system and the adverse factors causing the frequency change should be limited to ensure the measurement accuracy. The frequency is generally allowed to be determined by the allowable distortion error and the allowed phase error.
Application of sensor characteristics
(1) If the input and output are the most observable (known), then the transmission or conversion characteristics of the system can be inferred through the input and output (system calibration is to use such a process):
(2) If the system characteristics are known and the output is measurable, the corresponding input quantity causing the output can be inferred by the characteristic and the output (detection is the use of such a process);
(3) If the input and system characteristics are known, the output of the system can be inferred and estimated (the search for interference is the use of such a process).
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