High-performance harmonic analysis for reducing interference
The harmonic analysis is used to guarantee a high degree of reproducibility, even under interference such as fluctuating specimen temperatures or incorrect positioning of the specimen in the test coil. This ensures good long-term stability of the test results. As a rule, recalibration is not required even after a lot change.
The harmonic analysis requires powerful amplifier, such as the one used in the MAGNATEST testers. The alternating field magnetization of ferromagnetic components is described by the so-called "hysteresis curve", and this is a very sensitive indicator for numerous material properties.
So-called harmonics (odd multiples of the transmission frequency) are generated by the "high-energy" magnetic field excitation. The MAGNATEST is able to analyze this by means of a FFT.