Integrating Moving Average Filter Windows with Analog Converter Downsampling Rates
Aligning moving average filter lengths as integer multiples of ADC decimation rates eliminates aliasing foldover and maximizes noise bandwidth reduction.
Downsampling Rate
Decimation Ratio
Digital rate conversion parameters specify the integer factor by which discrete-time sequence sampling frequencies are reduced. The downsampling rate determines how many input samples are discarded for every sample retained in the output data stream. Decreasing the sampling rate lowers downstream computational overhead and storage requirements in continuous monitoring networks.
Integration qualification verifies that pre-filtering attenuates out-of-band frequencies before sample rejection occurs.
Nyquist Margin
Nyquist-Shannon sampling criteria mandate that signal energy above half the reduced sampling frequency must be eliminated prior to downsampling. Retaining every M-th sample stretches the discrete-time frequency axis by factor M. Without adequate anti-aliasing filtering, high-frequency signal components fold into the baseband, creating irreversible spectral overlap. The anti-aliasing filter cutoff must be set at or below half the target sampling rate to preserve signal integrity.
Signal Distortion
Group delay introduced by decimation filtering alters time-domain alignment of processed sensor signals. Linear-phase finite impulse response filters preserve waveform shapes but introduce constant temporal latency. Infinite impulse response filters minimize latency at the expense of non-linear phase response, introducing phase distortion near the cutoff band.
Selecting decimation factors as powers of two allows efficient multi-stage filtering structures that optimize computational efficiency.
Processing Boundary
System specifications enforce maximum allowable rate factors based on input signal bandwidth limits.