| 摘要 |
Remotely reading a utility meter wherein consumption of a utility is indicated by the movement of a mechanical component which is illuminated with coherent light which reflects off the mechanical component in a speckle pattern which is detected to produce a light detection signal. The light detection signal is processed to identify changes in the speckle pattern due to movements of the mechanical component. The processing may comprise identifying a set of features in the light detection signal, storing data representing the set of features and matching the stored data with the identified set of features. Other independent claims comprise; the mechanical component having at least one fiducial mark and detecting the movement of one or more fiducial marks through two successive spatial locations or twice optically detecting the movement of a fiducial mark through a spatial location during a cycle of the mechanical component and; determining the energy consumption using two time periods, the first time period being the time taken for a rotation of a rotating element depending on variations in a detection signal and the second time period being a time between two variations in at least one detection signal during the rotation of the rotating element. |
