A wide-band equalizer for a telecommunication system includes a symmetrical corrector and an asymmetrical corrector, each encompassing the entire band, and a multiplicity of parallel corrective networks centered on the midfrequencies of respective sub-bands. A set of input registers, one for each sub-band, serve for the storage of error voltages representative of the deviations of the signal levels in the equalizer output from predetermined reference values as required under certain (e.g., seasonally variable) operating conditions. A correction simulator, switchable between a symmetrical and an asymmetrical position, generates a group of compensating voltages representing the effect of either of the two overall correctors upon the signal amplitudes in different zones of the band; a group of summing circuits differentially combine these compensating voltages with the stored error voltages relating to the same band zones to provide a composite voltage which is read on an indicator and is minimized by adjustment of the two overall correctors. Thereafter, modified error voltages representing the residual deviations are fed into the input registers and thence to a resistance matrix distributing them to a multiplicity of output terminals, assigned to the several midfrequencies, with a polarity and step-down ratio corresponding to the effects of each corrective network upon the respective midfrequencies; a selector switch provides a reading of the cumulative effect of all the corrective networks upon each midfrequency, with the aid of a further summing circuit, as a basis for an individual readjustment of these networks.

A transmission arrangement provided with at least one adjustable network whose transfer characteristic between input and output as a function of the frequency .omega. within a prescribed frequency band is approximately equal to C exp [kf(.omega.)], where C is a constant and k a continuously variable parameter. A simple design as well as a large practically feasible adjustment range are obtained because the adjustable network comprises a plurality of channels between input and output and the transfer characteristic of a channel is approximately proportional to a term, different for each channel, from the series of terms of the development of exp [kf(.omega.)] to powers of kf(.omega.), the number of terms corresponding with the number of channels.

An amplitude equalizer is provided for equalizing amplitude distorted signals within a predetermined frequency band. The amplitude equalizer comprises first means for splitting signals into first and second split signals. A first delay device receives one of the two split signals, and a second signal splitter splits the output of the first delay device into third and fourth split signals, the third split signal being applied to a second delay device having a delay equal to the delay of the first delay device. The output of the second delay device is combined with the second output from the first signal splitter in a first signal combiner, the output of which is applied to a circuit for adjusting the polarity and gain of the signal applied thereto. The output of the polarity and gain adjusting circuit is applied to a second signal combiner which combines the adjusted signal with the fourth output from the second signal splitter to thereby provide equalized signals. As organized above, the equalizer can provide for arbitrary selection of the desired frequency regions and maximium equalized amplitude by simply varying either the amplitude or attenuation factor, and by properly choosing the delay time. Further, equalization of secondary and higher order distortion can be achieved by virtue of constant delay over the entire frequency region.

A network amplifier is provided. The network amplifier includes a variable equalizer having at least one control input and a variable attenuator having at least one control input. The network amplifier also includes at least one amplifier circuit that is coupled in series with the variable equalizer and the variable attenuator in a signal path of the network amplifier. The network amplifier also includes an automatic gain control circuit with a processor that monitors signals in the signal path and generates control signals for the control input of the variable equalizer and the control input of the variable attenuator to control at least one characteristic of the network amplifier.