Patent ID: 7496150

Claim:
Transmission apparatus for transmission of electrical signals between a line driver, which is connected to a transmission line, and a switching center, having: a) an analog feedback device for coarse setting of a line voltage level on the transmission line as a function of a line current which is detected in the line driver; and b) a digital feedback device, which is coupled to the analog feedback device via an analog/digital converter and a digital/analog converter and has a single digital feedback path having a feedback filter device for fine setting of an amplitude and phase relationship between the line voltage level and the line current, wherein c) the feedback filter device is designed such that a filter input signal can be converted to a filter output signal at a rate which is lower than the sampling rate of the analog/digital converter, wherein d) the feedback filter device comprises a first recursive filter unit, a non-recursive filter unit connected in parallel with the first recursive filter unit, and a second recursive filter unit which is connected in series with the parallel circuit formed by the first recursive filter unit and the non-recursive filter unit; and wherein e) the digital feedback device comprises a processing unit for carrying out signal processing in order to provide the switching center with a processed output signal, wherein the filter input signal is also supplied to the processing unit.