| 摘要 |
<p>Apparatus including an analogue-to-digital converter (26) having a given number of digits, includes a variable gain amplifier (23) for the input (VA) to the converter (26). If any one instantaneous value (21A) of the input (VA) is less than is necessary to saturate the converter (26), i.e. to use all the digits of the converter (26), the gain of the amplifier (23) is automatically set to amplify the instantaneous input (21A) to the extent necessary to saturate the converter (26). By such selective amplification of different outputs (VA), each instantaneous value (21A) is digitised by the full number of digits of the converter (26) and the resolution of the apparatus is the same for all inputs (VA) regardless of their magnitude. On the other hand the converter is not over-saturated such as could be the case if the different inputs (VA) were amplified by a common gain.</p> |
