The highpass filter can remove unwanted DC offsets and low-frequency hum from signals. In this example, the input signal is a 1 kHz sine wave superimposed on a linear ramp. Using a simple math channel filter of HighPass(A,100) we removed the ramp to leave a sine wave with zero offset.
In this example our input signal (blue trace, top) is a square wave of about 1.4 kHz with about 10% of low-frequency noise or "hum". With a math channel function of LowPass(A,200) we were able to extract this hum and display it as a separate trace (green, lower).
This type of filter is useful for extracting signals from wideband noise. In this example, a noisy 10 kHz sine wave has been filtered by the function BandPass(A,7500,12500). The result is a clean sine wave.
