| 摘要 |
<p>A control system for a gradient field generator, suitable for example for an NMR apparatus, includes filters which modify the field demand signal. The modification shapes the gradient field profile typically to compensate for the response characteristics of the NMR apparatus. Current generators (3a, 3b) supply currents to a plurality of individually magnetisable windings. The filters include different filters (F0, F1) corresponding to matrix currents (I0, I1) of different orders. The outputs of the different filters are summed to provide a control input for one of the current generators, and subtracted to provide the control input for the other of the current generators. The system thereby provides substantially decoupled control of the different field orders.</p> |
