A measuring device serves for the detection of a simultaneous presence of at least a first signal and a second signal in a measurement signal. The measuring device contains a receiving unit for receiving the measurement signal as a digital measurement signal and a processing unit. This processing unit includes a transformation unit for transforming the digital measurement signal into a measurement signal in the frequency domain. The processing unit further contains a subtraction unit for subtracting the first sideband of the measurement signal in the frequency domain from a second sideband of the measurement signal in the frequency domain. In this context, the subtraction unit generates a residual signal.