Patent ID: 9030193
Filing Date: 2015-05-12
Classification: G01N

Abstract:
1. An arrangement for quantifying the proportion of ferromagnetic particles in a medium, which arrangement comprises: a flow channel for the medium; a low frequency source, which is a sine wave generator or a triangle wave generator, to generate a feed for basic magnetization of the ferromagnetic particles; a high frequency source to generate an excitation for additional magnetization of the ferromagnetic particles, said high frequency source being connected to a carrier input of a modulator, in which case an output signal of the modulator is the excitation; a magnetizing winding round said flow channel, connected to the low frequency source, to generate a magnetic field in the medium; an excitating winding to be fed by the excitation round said flow channel to generate an additional magnetic field in the medium; a secondary winding functioning as a sensor of the magnetic field to measure change in the magnetic flux density of the medium, or to generate a response; and means for separating, a part from the response which is due to the magnetic non-linearity of the medium, wherein the arrangement further comprises means for generating the excitation from numerous frequency components so that a spectrum of the arrangement is wide in respect of spectra of typical interferences and at least nearly continuous, said means for generating the excitation comprising a third source, the output signal of which is a random signal and the third source being, connected to a modulation input of the modulator, and said means for separating from the response the part due to the magnetic non-linearity of the medium comprise after the secondary winding in order: a high-pass filter to remove low frequency parts from the response; a multiplier, to one input of which is connected through a delay unit a circuit feeding the excitating/magnetizing winding, and a bandpass filter to generate an actual signal; and a detector, to carrier input of which is connected the low/high frequency source through a frequency multiplier and phase shifter, to generate an output signal.