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What do AC/DC coupling mean in oscilloscope?
AC/DC coupling in oscilloscopes refers to the method used to input signals into the instrument. When in AC coupling mode, the oscilloscope only displays the alternating component of the signal, while DC coupling mode displays both the alternating and direct components of the signal.
AC coupling allows for the elimination of any DC offset or bias in the signal, resulting in a clearer and more accurate representation of the signal's amplitude and shape. It is also useful when analyzing AC signals that are superimposed on a DC offset.
AC coupling has a high-pass frequency response, which means it attenuates low frequency signals while passing high frequency signals. DC coupling, on the other hand, has a flat frequency response, allowing for the measurement of both low and high frequency signals.
Yes, most oscilloscopes have a coupling control that allows the user to switch between AC and DC coupling modes. Some oscilloscopes also have a third option, called DC-50Ω, which combines DC coupling with a 50Ω input impedance to match the impedance of certain sensors or generators.
One limitation of AC coupling is that it cannot accurately measure the DC component of a signal. Additionally, using AC coupling on a signal with a very low frequency can result in a distorted waveform due to the high-pass filter effect. In these cases, it is best to use DC coupling or a combination of AC and DC coupling for more precise measurements.