Abstract: The invention relates to the filtering of a subfrequency band out of a receive frequency band, in which a carrier frequency for prefiltering the receive frequency band and an intermediate frequency for demodulating the frequency band filtered out during the prefiltering and for generating a frequency baseband are inserted into the signal propagation path, in which the desired subfrequency band is filtered out of the frequency baseband by a post-filtering and in which the carrier frequency, the intermediate frequency and the post-filtering are matched to one another.

Abstract: The invention relates to a system for unidrectional or bi-directional signal transmission between at least two elements (E1, E2), which constitute components of an electric power supply and signal transmission system (EVS) of vehicles. According to the invention, one of the elements (E1) is connected to at least one Bluetooth radio module (B1) and one of the other elements (B2) is connected to at least one Bluetooth radio module (B2). The unidirectional or bi-directional signal transmission between the elements (E1) and (E2) and to the Bluetooth radio modules (B1, B2) takes place via an electric cable, but is wireless between the Bluetooth radio modules (B1, B2). Several elements (E1, E2) that are connected to Bluetooth radio modules (B1, B2) can be combined to form a Bluetooth pico-network. The Bluetooth radio modules (B1, B2) permit bi-directional signal transmission. A maximum of eight Bluetooth radio modules (B1, B2) can transmit signals to each other in a Bluetooth pico-network.