| 摘要 |
The system uses inductive coupling to provide an enhanced signal to noise ratio. The system (30) provides detection of a charge modulation signal (S1) by means of inductive coupling. It comprises an aerial circuit comprising a coil (L1, T1) and a circuit (1,2,R1) for applying an excitation signal (V0) of predetermined frequency (F0) to the aerial. Phase comparators (3) receive the excitation signal on a first input, and a signal sampled from the aerial circuit (L1) on a second input. The aerial circuit (L1) does not form a resonant circuit in the region of the excitation signal frequency. The phase comparator (3) receives on its second input a signal (V(lm)), delivered by the device (31) which detects the current (lm) passing through the coil (L1).
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