Suppression Ratio
Electronic filters provide a specific reduction in the amplitude of unwanted signal components that fall outside the Nyquist frequency. The performance of aliasing attenuation determines how effectively a system prevents high-frequency noise from appearing as legitimate low-frequency data. It is measured in decibels relative to the passband gain.
Filter Specification
Anti-aliasing hardware typically employs a multi-pole low-pass design to ensure steep roll-off characteristics. If aliasing attenuation is insufficient, the sampler folding process introduces phantom signals that corrupt the primary measurement. A designer calculates the required depth based on the dynamic range of the analog-to-digital converter.
High-order filters are used to maximize this protection before the signal reaches the conversion stage.
Signal Integrity
The rejection level depends on the transition band width and the sampling frequency. High aliasing attenuation allows for a wider usable bandwidth but often introduces phase distortion near the cutoff point. Passive components may suffer from tolerance variations that degrade this value in field conditions.
Metrological Verification
Test engineers verify the suppression by sweeping a signal generator across frequencies exceeding half the sample rate. The resulting data confirms that the aliasing attenuation level keeps the residual power below the noise floor of the instrument.
