A signal processing device and signal processing method is provided that includes a detection unit for detecting a signal strength of a signal, whereby the detection unit is configured to output a detection value that represents the signal strength of the signal; a settable digital filter connected upstream of the detection unit, whereby filter coefficients for setting a transfer characteristic of the filter are assigned to an amplification or attenuation of the signal by the filter; a digital multiplication unit, which is connected upstream of the detection unit for amplification or attenuation of the signal, whereby the multiplication unit is configured to compensate partially for the amplification or attenuation of the filter, whereby the compensation is encumbered with a residual error; and a correction unit to apply to the detection value a correction value at least partially compensating for the residual error.