| 摘要 |
In the inductive measurement of signals at a defined frequency or in a defined frequency range, the external electromagnetic interference can be stronger than the signal A to be measured. This problem has been solved by an interference-suppression coil 3 being wound around or parallel to and essentially along the entire length of a signal-receiving coil 2, the coils 2, 3 surrounding the same signal source. One end of the interference- suppression coil 3 is electrically connected to the opposite end of the signal-receiving coil 2, while the other end of the interference-suppression coil is connected to earth, suitably via an electrically passive component 4, for example in the form of a capacitor. The passive component 4 is selected according to the properties of the two coils 2, 3 so that the system has a resonant frequency which corresponds to the frequency content of the signal A. The interference-suppression arrangement will thus damp out all frequencies apart from the signal frequency. <IMAGE> |
