An overlay protocol and system for allowing multicast routing in the Internet to be performed at the application level. In some aspects, the apparatus accepts an excitation signal and the amplitude modulated signal and divides the amplitude modulated by the excitation signal to produce an output signal that is proportional to the position of the object being sensed. Responsive to the current cache memory usage exceeding the memory threshold, cache records are selected to be offloaded. In this electronic apparatus, a large number of optical connectors of optical fibers can be connected and arranged in a restricted space. The clock signal generation unit continuously generates the boosting clock signal during a predetermined period in which the imaging operation starts and, after the predetermined period, generates the boosting clock signal during at least part of a blanking period of the vertical synchronization signal and the horizontal synchronization signal. The measured data is transferred from the terminal unit via a short-range radio technology to a data monitor arranged at the patient’s bedside when the patient is in the vicinity thereof.