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.
Phase Distortion
Signal Alteration
Analog and digital transmission systems introduce varying time delays for different frequency components of a signal, altering its waveform. This phase distortion occurs when the phase response of a circuit or transmission medium is not linear across the frequency band of interest. The resulting shift deforms complex non-sinusoidal waveforms, such as square waves or multi-frequency sensor signals.
Filter Impact
Reactive components in analog filters naturally cause frequency-dependent phase shifts that are most pronounced near the cutoff frequency. Designing with active analog filters requires careful optimization to balance phase linearity against amplitude attenuation. In digital systems, finite impulse response filters are preferred because they can achieve perfectly linear phase, eliminating this error entirely.
Measurement Consequence
Dynamic measurements, such as vibration analysis or transient pressure monitoring, rely on accurate waveform shapes to identify signal features. When phase distortion is present, it can cause incorrect peak amplitude measurements and skew the timing of events.
Compensation Method
Calibration laboratories use arbitrary waveform generators and digital oscilloscopes to measure the phase response of the acquisition chain. Engineers apply mathematical correction algorithms to the digital output to compensate for known phase shifts introduced by the analog front end. This calibration ensures that the time-domain characteristics of the physical signal are accurately preserved.