To get an analog signal into a computer system, we need to send it through an analogue-to-digital converter. This device will turn it into a stream of digital pulses that our computers can understand. But before this can happen, an intermediary stage of processing must be taken place. Small-voltage signals must be amplified to the appropriate level. Interference must be removed, and faulty circuits must be grounded to protect the rest of the system.
This intermediary stage is called signal conditioning. Incoming signals are processed so that they can be put to better use by the stages that follow. Thus, signal conditioners are crucial pieces of hardware, and for good reason ever-present in the industrial controls sold by Allied Electronics. But they’re also used on a smaller scale in smaller devices.
How Does Signal Conditioning Work?
Signal conditioners come in a range of different types. Let’s take a look at a few of them.
Filtering
Getting rid of unwanted AC frequencies is essential in many applications. You might have heard the hum that comes when a 50Hz power line is inadequately filtered and put through an audio system. In other cases, a signal might need to be ‘cleaned up’ by removing high-frequency noise.
Level Control
Getting the voltage to a level appropriate to the ADC is critical. Signals can be either amplified (that is, turned up) or attenuated (turned down). In the former case, this is done to decrease the amount of noise that might creep in between the signal conditioner and the ADC and to ensure the maximum possible resolution on the signal being sampled. Attenuation ensures that the voltage does not go beyond the maximum on the ADC, which would result in clipping.
Linearisation
In some cases, the signal coming in might be nonlinear. In an exponential signal, massive change might occur in just a few digital ticks. Converting it into a linear signal allows the ADC to record smoother and more useful data.
Electrical Isolation
In some cases, it might be necessary to protect potentially sensitive equipment by isolating one part of the circuit from another. Magnetic couplers work by turning an incoming voltage into a magnetic field and back again, optical couplers do this turning the signal into a beam of light. This process ensures that any problem in one part of the system won’t cause damage to the rest of it. This doesn’t just protect equipment, but the people using it, too.
