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What Is a Signal Conditioner?

A signal conditioner is a device that converts a continuously variable, or analog, electrical signal into another type of signal. In so doing, it manipulates the signal so that it can be read and processed by conventional instrumentation, such as control devices and systems. The signals produced by applications such as temperature and vibration sensors often require signal conditioning before they can be measured accurately.

Amplification
- A signal conditioner can amplify the magnitude of an electric signal prior to processing. Some sensors produce voltage signals in the order of millionths of a volt, or microvolts, which can easily be drowned out by electrical interference, or ̶0;noise,̶1; from the wires carrying the signal or other electrical components in the vicinity. However, an external signal conditioner with amplification located close to the sensor can boost the signal without introducing appreciable noise, which allows for more accurate measurements.
Filtering
- A signal conditioner can also filter out sounds within a certain frequency range that constitutes electrical noise. Power supplies and machinery typically generate electrical noise at a frequency of 60 hertz, or 60 cycles per second, but by applying what is known as a lowpass filter, a signal conditioner can eliminate this unwanted high-frequency component from the signal. The range of frequencies filtered out by a lowpass filter, known as its bandwidth, must not affect the response of the signal conditioner to changes in the values of electrical signals over time.
Linearization
- Some types of sensors, including thermocouples, thermistors -- resistors whose resistance varies according to temperature -- and strain gauges produce electrical signals that are not directly proportional to the physical quantities they measure. According to leading signal conditioning manufacturer Analog Devices, the temperature coefficient of a thermistor varies by over 70 percent over the temperature range between 32 degrees Fahrenheit and 212 degrees Fahrenheit, and without linearization, its nonlinear response is the biggest source of errors in temperature measurement. However, a signal conditioner can convert nonlinear signals from a sensor into linear signals before they enter the next stage of processing, thereby eliminating such errors.
Cold-Junction Compensation
- A thermocouple is a device that measures temperature as the difference in potential difference, or voltage, between two dissimilar metals or metal alloys welded together. A signal conditioning technology, known as cold-junction compensation, improves the accuracy of thermocouple measurements by adjusting the thermocouple signal to take into account changes in room temperature.

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