Error Mechanism
Signal processing path non-linearities transform high-frequency multi-axis vibration signals into spurious low-frequency DC bias shifts inside sensor demodulation electronics. Error budget analyses identify phase dependent cross rectification as a primary driver of uncompensated bias drift in vibration-exposed inertial measurement units. Calibration standards mandate dynamic vibration rectifying sweeps to establish sensor compliance for aerospace application sourcing.
Phase Coupling
Simultaneous transverse and axial structural vibrations induce concurrent mechanical displacement and capacitive carrier modulation within differential sensor channels. When a phase offset exists between input acceleration vector components, phase dependent cross rectification occurs as non-linear front-end operational amplifiers multiply co-existing phase-shifted signals, producing a continuous DC offset at the demodulated output. Synchronous demodulators fail to reject these cross-coupled terms when vibration frequencies match multiples of the sensor drive carrier frequency.
Verification routines isolate this error mechanism by mounting sensors on dual-axis shaker tables and sweeping inter-axis phase angles from zero to three hundred sixty degrees while recording output bias shifts.
Signal Demodulation
Demodulation clock timing jitter shifts carrier sampling points, increasing sensitivity to phase-shifted transverse mechanical vibrations. Mitigating phase dependent cross rectification requires precise matching of high-frequency phase response across differential amplifier chains and drive loop electronics. Sensor designers implement closed-loop force feedback to minimize physical mass displacement and prevent non-linear signal mixing.
Frequency Boundary
Vibration frequencies approaching the carrier demodulation frequency bound the operating region where phase-locked filtering suppresses rectifying errors. Beyond this operational frequency, phase dependent cross rectification generates uncompensatable low-frequency noise that corrupts navigation position calculations. Acceptance testing protocols document maximum allowable vibration rectification coefficients across specified frequency bands.
