| 摘要 |
<p>The testing appts. uses an electronic calibrating device to replace the standard second probe and chain for measuring a reference component. The reference voltage is produced using an added RAM in which the input is connected to the output of the original RAM through a switch and a digital-to-analogue converter. - One input of the D-A converter is connected to the output of the additional RAM and one output of the D/A converter is connected to one input of the differential amplifier whose other input receives the signal from the component under test. The reference signal is thus stored using a reference component and is then electronically input to the differential amplifier in a reproducible manner while checking the components under test. EPAB- EP--88652 B Apparatus for the non-destructive testing of articles by eddy-currents comprising an excitation generator (10), a probe (14) connected to said generator, the probe having therein sampling means for a measurement potential (Vm) corresponding to an article being tested generating means for a reference potential (Vr) corresponding to a standard article, a differential amplifier (20) having first (20/1) and second (20/2) inputs and an output, the first input receiving the measurement potential and the second receiving the reference potential digital signal-treatment means (24) having an input connected to the output of the differential amplifier (20) a cross and amplifier (22), said treatment means comprising in succession an analog digital converter (30), a first direct-access live memory (32) and a digital treatment circuit (34) characterised in that the generating means for the reference potential comprise a second direct access live memory (40) having an input (39) and an output (42), the input being connected to the output of the first live memory (32) across an interrupter circuit (37), and a digital-analog converter (44) having an input (43) connected to the output (42) of the second memory (40) and an output (45) connected to the second input (20/2) of the differential amplifier (20). (9pp) USAB- US4556846 A The device includes an exciting generator, a probe connected to the generator, and a probe sampler. An input of a differential amplifier receives a measuring voltage and a reference voltage. A digital signal processor has an input connected to the output of the differential amplifier across an amplifier. The processor comprises an analog-digital converter, a random access memory and a digital processing circuit. - The reference voltage is generated using a second random access memory having an input and an output, the input being connected to the output of the first random access memory across a switching circuit and a digital-analog converter having an input connected to the output of the memory and an output connected to the second input of the differential amplifier.</p> |
