Signal Conditioning For Accurate Sensor Measurement
Proper signal conditioning is critical to any industrial data acquisition or industrial control application. Many sensors do not provide a clean and clear signal due to various reasons such as electrical or RF noise, or wire loss. For example, a thermocouple operating in an environment with large electric motors will pick up electrical noise which affects the signal such that sensing and acquiring a valid temperature from the raw signal can be impossible. Such signals require signal conditioning before being captured and processed by a data acquisition device.
Signal conditioning includes many different processes, but some of the most common are amplification, isolation, filtering, excitation and linearization. In addition, cold-junction compensation is critical for accurate thermocouple measurements. A few examples of signals that may require a signal conditioner include: thermocouples, thermistors, RTD’s, mag pickups and other proximity probes, LVDT, and strain gauges.
A signal conditioner can also perform the functions of a signal converter by converting a raw signal from analog to a different form of analog or from analog to a digital signal. Common examples include the conversion of a thermocouple signal to a 4-20mA signal (analog) or to a form of field bus (digital).