Most signals require some form of manipulation that prepares them for the next stage of processing. This is a crucial process for making analogue signals like temperature and vibration intelligible to data acquisition systems or control equipment. If an incoming signal is not optimised for the in-line digitizer via signal conditioning, it can result in measurement inaccuracies and suboptimal levels of performance.
Signal conditioning needs vary in capabilities depending on your sensor. Different measurement types and sensor architectures have different signal conditioning requirements. For example, low-voltage analogue signals will typically need to be amplified and subsequently filtered to reduce background noise before digitization. Other sensors may need to be excited by an external voltage to measure mechanical changes as a function of varying electrical resistivity.
In this article, we explore the fundamentals/process of signal conditioning, specific conditioning requirements needed for the most common sensor types, and considerations when designing a measurement system.
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Processes of Signal Conditioning
Adjust Your Signal-to-Noise Ratio with Amplification & Attenuation
In the context of electronics, amplification and attenuation are opposites. Analogue signals are subject to deterioration during transmission due to background noise. The ratio of signal strength to unwanted background interference is known as the signal-to-noise ratio. Amplification is the process of increasing this ratio by magnifying the voltage level of the input signal. Converting a 0-10mV signal to a 0 -10V signal is an example of amplification.
Attenuation, by contrast, is the process of decreasing the input amplitude, for example, to get it to fit within the optimal range of the device digitizer.
Remove Voltage Signals and Prevent Damage to Equipment
Signal conditioning often requires the input signal to be filtered and isolated to remove unwanted background noise and remove voltage signals that are far beyond the range of the in-line digitizer. Filtering is commonly used to reject noise outside of a pre-defined frequency range. Isolation is similar, but it is mainly used to protect the data acquisition or control system from voltage spikes that could damage the equipment.
Excitation Techniques Using a Controlled Current or Voltage
Excitation is required for many types of transducers. External power is required for the operation of an active sensor. For example, strain gages, accelerometers, thermistors, and RTDs require external voltage or current excitation.
Signal Linearization: Mapping Voltage of the Input Signal
Linearization is a form of signal interpretation that is used when sensor equipment produces signals that do not exhibit a linear relationship to the actual measurement. It is used to map the voltage of the input signal from the sensor against the corresponding value of the physical measurement. This is a common signal conditioning process for industrial temperature measurements.
Signal Conditioning is Part of the Sensing System
A signal conditioner is a device that converts one type of electronic signal into a different kind of signal. Its primary use is to convert a signal that may be difficult to read by conventional instrumentation into a more easily read format. In performing this conversion, several functions may take place.
Here's a great recap of Signal Conditioning by NTS, Signal Conditioning, via YouTube
Sensor-Specific Signal Conditioning
Understanding the signal conditioning needs for each measurement type is an essential aspect of achieving the best measurements.
There are specific signal conditioning needs based on the sensors you require to perform an application. The most common temperature sensors used to measure temperature are Thermocouples, RTDs, and Thermistors.
Below is a summary of the signal conditioning types for the different sensors and measurements.
Signal Conditioning Types
source: Engineers Guide to Signal Conditioning
TT Electronics offers a variety of specific resistor parts and sensors.
High Precision Resistive Components for Signal Conditioning Designs
PTS – platinum temperature sensor
CAR – high precision through-hole film resistor, with matching service available
DIV23 – high precision voltage divider
WIN & PCF – high precision chip resistors
QS014 – R-2R ladder network used in analogue to digital conversion
QSOP – customizable precision resistor networks
HVD – high voltage divider
Conclusion
TT Electronics is committed to innovation in all areas of engineering and technology, offering a suite of advanced products for some of the most top specification markets worldwide. We offer a broad range of sensors and integrated precision resistor networks with signal conditioning capabilities.
If you would like any more information about signal conditioning with TT Electronics, contact a member of our team directly.