Digital moving-average filter

An example is the relatively simple moving average filter. In case of a digitized signal, the values of a fixed (odd) number of data points (a window) are added and divided by the number of points. The result is a new value of the center point. Then the window shifts one point and the procedure, which can be considered as a convolution of the sipal with a rectangular pulse function, repeats. Of course, other functions like a triangle, an exponential and a Gaussian, can be used. 

This filter can be implemented in a digital computer. Other filters, such as a moving-average filter, are also possible [7]. 

Evaluate both analog and digital exponential filters, as well as a moving-average filter, and assess the effect of sampling interval Af. 

Figure 17.6 A comparison of filter performance for additive sinusoidal noise (a) square-wave plus noise (b) analog exponential filters (c) digital exponential filters (d) moving-average filters.

This process of moving the filter function through the raw data and calculating weighted averages is called convolution, and the digitally filtered data d, d2, 3,. .. are called the... 

To learn about digital filters, such as the nonrecursive moving-average and polynomial filters, as well as the recursive Kalman filter... 

Figure 3.3. Two-point moving average digital filter.

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