Signal Conditioning

Signal Conditioning

Signal Conditioners are used to amplify sensor signals and correct for problems such as ground loops. Signal conditioners is a broad category that includes several different types of devices: signal conditioners, signal converters, signal transmitters, signal alarm modules, signal isolators, amplifiers, and preamplifiers.

Field temperature and pressure transmitters are in a different department. Visit Process Measurement to purchase.

Some manufacturers of sensors will have an option for a signal conditioner built into or for remote mounting. However, in other cases, there is a need for an external signal conditioner or converter to provide the desired output signal, more attractive price, or better specifications.

Signal conditioners are ancillary devices intended to amplify, filter, condition, scale into engineering units, linearize, and convert raw signals produced by transducers and convert it to an industry standard signal such as 0-10 VDC or 4-20 mA. These raw signals are usually very low voltage and susceptible to picking up electrical noise from surrounding equipment and power lines. Conditioned signals are better able to be transmitted longer distances and through electrically noisy environments. Another function may be to also provide signal isolation, i.e. signal isolators.

Generally, the output signals from the sensor may be in the form of either a pulse or analog current / voltage that is proportional to the span of the signal being measured. Open collector transistors are common as pulse output signals.

The most common analog signal is a 4-20mA. In many flowmeter types the frequency of the raw input signal carries the flow information. The frequency is related to flow rate. Each pulse or cycle is related to a small equivalent quantity of flow. The quantity represented by each pulse varies with each individual meter and must be scaled to obtain engineering units. The input signal to a pulse signal conditioner may be a contact closure, a magnetic pickup, or a low level pulse. Some conditioner/converters scale the pulse signal such that each pulse represents a engineering quantity of flow (for example 1 pulse per gallon). Some converters convert the variable frequency signal into a current proportional to flow rate.

In nearly all cases the signal conditioner is intended to be powered by a DC supply voltage normally available in most instruments with 24 VDC being the most common. Signal conditioners are typically without a display and for mounting inside an enclosure rated for the environment. DIN rail type being the most common mounting style.
 

Signal Conditioner Application Example