| 摘要 |
The invention is a method and a corresponding arrangement for continual determination of a signal's mean value over a just expired time period of predetermined length, for example, over the past 10 minutes. The signal is converted to digital form, if so required, and its current value is parallel read periodically into a number of shift registers corresponding to the number of bits in the signal, all of them having the same length or bit capacity. The bit capacity of the shift register and the reading-in frequency are chosen such that the time taken to fill the entire shift registers with current signal values coincides with the length of the time period during which one wishes to determine the mean value of the signal. During each time interval between two consecutive readings of the signal's current value into the shift registers, the contents of the shift registers are circulated at least once and preferably a number of full cycles, so that all signal values present in the shift registers appear in quick pace one after the other at least one time at the outputs of the shift registers. The digital signal present at the outputs of the shift register is converted into a corresponding analogue signal, which is integrated over a period of integration which corresponds at least to the time taken for circulation of the signal contents in the shift registers one full cycle. The thus integrated signal is a measure of the mean value of the supplied signal over the just expired time period with aforesaid length. <IMAGE> |
