| 摘要 |
PCT No. PCT/DE90/00389 Sec. 371 Date Apr. 17, 1991 Sec. 102(e) Date Apr. 17, 1991 PCT Filed May 26, 1990 PCT Pub. No. WO91/02985 PCT Pub. Date May 7, 1991.A measuring circuit (MS) for measuring the value of an impedance in an impedance network includes an oscillator device (OSZ1), a second oscillator device (OSZ2), a phase-controlled rectifier (PG), a reference/actual value comparison point (AG) and an integrator. The first oscillator device feeds a first alternating voltage of constant amplitude and constant frequency to a first output connection (A1). The second oscillator device feeds a second alternating voltage of the same frequency, but with adjustable amplitude and with phase shifted by 180 DEG , to a second output connection (A2). The amplitude of the second alternating voltage depends on the phase of the signal which is transmitted to the phase-controlled rectifier via an input connection (E). If the input signal is in phase with the second output signal, the amplitude of the second output signal is reduced. However, if the input signal oscillates in opposite phase to the second output signal, the amplitude of the second output signal is increased. This change of amplitude is effected by the integrator which integrates the signal, which is rectified and compared with a reference value, and transmits the integration value as amplitude adjusting value.
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