A sensing edge for providing a signal to a controller indicating that a forward edge of a door is obstructed during operation. Images registered with a database 16 and the names of albums having been registered are shown on a screen of the user’s personal computer. An electrically conductive shell is provided and is formed of at least one layer of a conductive material enveloping the elongate member and forming a second intimate bond with at lease a portion of the conductive contact terminal immediately adjacent the first intimate bond. Preferably the cavitation fluid reservoir serves the dual function of fluid reservoir and degassing chamber. When the radio-frequency channel is experiencing low levels of channel interference, less channel coding is necessary and the vocoder having a higher encoding rate is used.