Techniques for explicit feedback delay measurement are described. An absorber structure is suspended over the electrode structure and spaced a first distance apart from the first electrode structure. As a result, the fuel consumption rate can be reduced in correspondence with the plurality of types of fuel supplied to the engine, for example. If the number of data symbols is less than M, the padding unit pads the block of data symbols with at least one padding symbol. The user relevant information includes information about a virtual user community relevant to a first user identifier. The LED-based illumination subsystem is automatically driven by the automatic light exposure measurement and control subsystem responsive to the generation of control activation signals by the image sensing array and the automatic object presence detection subsystem during object illumination and image capture operations.