Dynamic Characteristics Of Transducers
Dynamic Characteristics of Transducers
Dynamic characteristics relate the response of the device to variations of the measurand with respect to time. The most important ones are the frequency and step-response characteristics.
Frequency Response of Transducer
Frequency response-can be defined as the variations in the output curve given a sinusoidally varying, constant amplitude, input measurand, see Figure 1.9. Please note that the output is normally shown as a ratio of the output amplitude divided by measurand amplitude, expressed in percentage.
Step Response Of Transducers
Step response-can be defined as the variation in the output value given a step change in the input measurand value. The time required for the output to reach a specified percentage of the final value is termed the ‘response time’. These specified percentages are usually 10% and 90% of the final value.
As shown in Figure 1.10 there are four main types of response time:
- Delay time-the time taken for the output to rise to 10% of the final value once the input step has been applied.
- Rise time-the time taken for the output to rise from 10% to 90% of the final value.
- Storage time-the time taken for the output to fall to 90% of the final value once the input step has been removed.
- Fall time-the time taken for the output to fall from 90% to 10% of the final value.
Other important elements of the output characteristic are noise and noise margins, which can be defined as:
Noise-the level of any spurious signal(s) appearing at the output of the device due to any cause other than the driving input physical quantity.
Noise margin-the maximum noise level that can be tolerated by the device before it has any significant effect on the output signal.