A method is provided for initiating communications over a channel between a transmitter and a receiver within a specified spectral range, subject to a mask to be applied at the transmitter so as to attenuate at least one segment of the spectral range. A signal processing unit is included to process and compare a characteristic of the proximity signal that is changes or attenuates with distance between the two catheters, such as impedance, amplitude andor phase. Referring to menus, methods may include receiving potential information for a first menu, and receiving indications of associations of the information with the first menu andor any number of additional menus. The processor may encode or decode the video information. A third embodiment has a circular toroid volumetric shape with an elliptical cross-sectional shape.