| 摘要 |
The electronic trigger has analogue circuit (1,R,C) for measuring electrical signals, an analogue/digital converter (3), with input (2f) connected to the analogue circuit, a digital processor (4) and offset correction device. The offset correction includes a high pass digital filter and the processor at the output of the converter. The digital filter is initialized during an initialization stage. During the initialization, connection to earth of the converter input (2f), the input into memory of the converters output signal and zero reset of the value (S0) corresponding to the digital filter output is executed. For each sample (Ei) from the converter (3) the filter calculates the output value (Si) according to the equation: Si = Si-1 - alpha Si-1 + Ei - Ei-1 in which i corresponds to a considered sample range, alpha is a constant a function of the sampling period (T) of measured signals and rupture frequency (Fc) of the digital filter, S0 and E0 are the values of the output signals of the convertor (3) produced during initializing. |
