Configuring Moving Average Filter Lengths for Decimated Signal Processing
Matching moving average filter length to the decimation factor eliminates alias leakage by placing transfer function zeros directly on downsampling fold points.
Decimation Factor
Digital Signal Processing Parameter
Digital signal processing parameters define the integer ratio by which a sampled data rate is reduced during filtering and downsampling. The decimation factor determines the final bandwidth and resolution of the processed signal by selecting every Nth sample from a high speed stream. Increasing this value narrows the frequency range while typically improving the signal to noise ratio.
Bandwidth Reduction
A high sample rate is often necessary to capture transients, but a lower rate is preferred for storage and analysis. When the decimation factor is applied, the system must first use a digital low pass filter to prevent aliasing. This step ensures that no frequencies above the new, lower Nyquist limit remain in the data.
Computational Efficiency
Processing power requirements scale with the amount of data moving through the system. By applying a large decimation factor, an instrument can focus its resources on a specific band of interest without being overwhelmed by unnecessary samples. This optimization is common in software defined radio and high resolution vibrometry.
Output Rate
Calculating the final output rate requires dividing the original sample clock by the value of the integer chosen for the operation. This process balances resolution against storage.