| 摘要 |
Circuitry for digitising the signal produced by for example a strain gauge bridge (10) comprises a signal processing channel (20) including an amplifier and A-D converter connected to the bridge output by a semi-conductor switch (18) controlled by a microprocessor (22) which periodically changes over the switch (18) so as to digitise a calibration signal derived from the energising source (12) for the bridge by means of a signal attenuating high stability amplifier (32) and a high stability voltage divider (30). The microprocessor scales the output of the channel (20) by a multiplying factor the magnitude of which is such that its product with the value ale represented by the digitised calibration signal is always constant. In this way, any drift is compensated for by change in the magnitude of the multiplying factor. <IMAGE> |
