VARIABLE-INDUCTION PICKUP OF ELECTROMAGNETIC FIELD Russian patent published in 1997 - IPC

FIELD: electrical engineering. SUBSTANCE: device has parallel oscillatory circuit consisting of measuring induction coil 1 and capacitor 2. Controlled square-pulse low-frequency generator 3 and high-frequency generator 4 of sinusoidal voltage are connected with their inputs to one of the leads of coil 1. In oscillatory circuit, signal is formed of mixture of oscillations induced by generators 3 and 4 and free oscillations. Coil 1 induces electromagnetic field of complex modulation. Field of this type has high information content, and it increases sensitivity of pickup. Multiplier 5 connected to outputs of generators 3 and 4 forms signal containing the information of change in electromagnetic field of coil 1. Device 6 separates direct component from this signal. Variations of direct component level correspond to changes in electromagnetic field of coil 1. EFFECT: higher sensitivity. 4 cl, 2 dwg