Abstract: Electric low current signals are transmitted through two-wire circuits having coaxial connectors which are closed by windings that are coupled transformer-like to the coaxial connectors. This arrangement allows transmission of control signals for electric power consuming devices within automobile doors, low frequency audio signals, and electrical power to power the electric consumers. All signals are transmitted on a common data cable. Control signals are in binary coded form, modulated onto a carrier signal, as are modulated, low frequency audio signals. The signals are demodulated in a door module and separated according to frequency. The low frequency audio signals are amplified and transmitted to a loudspeaker. The control signals are processed by a microprocessor controller in conjunction with switching units that create corrective actions for the power consuming devices located in the door.

Abstract: Control signals for electric consumers in vehicle doors and l.f. signals for loudspeakers in vehicle doors are transferred from a control apparatus (1) provided outside of the door over a common data line (42, 43) to a door module (20, 30). For this purpose, in the control apparatus (1) the control signals are modulated in binary-coded form onto a carrier signal and onto the same carrier signal there is also modulated the l.f. audio signal. In the door module 30) the signals are demodulated and separated according to frequency. The l.f. signals are amplified and fed to a loudspeaker (4, 5). The control signals are evaluated by a micro-controller (24, 34) and they control over switching stages (23, 33), setting elements (6, 7) provided in the door. Conversely there is also possible a data transfer from the door module (2, 3) to the control apparatus (1).