Field Variation
Rate of change of an electromagnetic or physical quantity is measured across a defined distance in a coordinate space. Utilizing spatial gradients allows sensors to determine the direction and intensity of localized field variations. This measurement is independent of the absolute strength of the background field.
Sensor Array
Multiple sensing elements are positioned at fixed intervals to capture the field strength at several points simultaneously. The differences between these measurements reveal the spatial structure of the field. This layout is used to detect cracks or localized anomalies in metal plates.
Gradient Measurement
High-precision instruments subtract the outputs of closely spaced sensor coils to isolate localized magnetic variations from uniform background fields. This subtraction is performed using analog differential amplifiers or digital signal processing routines. Because uniform external fields affect both coils equally, the subtracted output remains zero unless a localized gradient is present.
This method is effective for identifying tiny cracks or material boundary transitions in industrial environments.
Noise Mitigation
Common-mode interference from distant power lines or electrical machinery is canceled out by the differential sensing arrangement. This cancellation improves the signal-to-noise ratio in environments with high electromagnetic noise. The distance between the sensing elements is optimized to maximize gradient sensitivity while maintaining noise rejection.
