Calibration circuit for digital level meter - has digital store to which reference voltages are applied during calibration phase

摘要

The circuit consists of a voltmeter to which the voltage to be measured is applied. It is followed by an A/D convertor, an arithmetic unit taking logarithms of each digitalised voltage value, taking into consideration a reference voltage value stored in a digital store, and a display unit. The digital store (6) is connected to the output of the A/D converter (3) during a calibration phase in which a reference voltage (Uo, Ur) is applied to the input (1) of the level meter. This digitalised voltage value written in the store (6) is used as the reference voltage (UB) for the logarithmation.