A receptor positioning device for taking dental bitewing radiographs of a patient’s teeth comprises a receptor holding member adapted to receive a receptor for exposing x-radiation from the x-ray machine and a collimation plate having a substantially flat surface for aligning with an x-ray machine. Consistent with one embodiment directed to a signal processing system that detects faint incoming signals, the analog and digital circuits are implemented on a single piece of silicon. The IEEE 1394 configures packets with memory information and the IP operates under channel based IO thereby necessitating a modification of the data transfer scheme to accomplish IP transfers over the IEEE 1394. The pressure sensor can be adapted to measure a pressure surrounding the catheter, and the antenna can be adapted to telemetrically communicate the measured pressure to an external device. Moreover, because the appearance pattern can be painted or printed on the inner surface of the transparent plastic layer, the appearance pattern will not come off because of frequent touching.