Transmission device for transmitting a wanted signal modulated on a carrier

A circuit arrangement to eliminate distortion from information in a useful signal (NS), which is modulated to a carrier oscillation (TS) with double sideband modulation, and which is received distorted because of transmission by a receiver, having a bandpass filter (5) that is tuned to a frequency (f(T)) of the carrier oscillation (TS), which precedes a demodulator (6) of the receiver, and having an error signal circuit (9) for controlling a transfer factor of the bandpass filter (5), which recognizes oscillations in the bandpass filter (5), whose amplitude remains below a threshold value (SW) adjusted by the error signal circuit (9), and that produces an error rate signal (FS) corresponding to a frequency of recognized error oscillations, characterized in that

• a quality setting circuit (7) is connected to the bandpass filter (5) and has a quality transducer curve (10) set in the quality setting circuit (7), having a control input that receives the error rate signal (FS), resulting in an adjusting of a filter quality (G) from the bandpass filter (5) so that when the error rate signal is missing, where a filter bandwidth (Bf18) of the bandpass filter (5) is at least equal to a transmission bandwidth of the useful signal (NS), and the error signal circuit (9) produces the error rate signal (FS) at a maximum value (FS.sub.m), the filter quality (G) reaches substantially a maximum quality value (Gm) before an onset of oscillation of the bandpass filter (5) and the carrier oscillation (TS) exhibits an overvoltage in an output of the bandpass filter (5).