The invention relates to a test device for testing the transmission quality of radio devices by integrating a noise generating device in the transmission chain of the test device. To this end, data to be transmitted are imaged on individual partial data streams modulated onto signals associated with the partial data streams and having different carrier frequencies. At this point in the transmission chain, a noise proportion for at least a part of the signals is added to one signal each of a carrier frequency, in order to allow frequency-selective control of the noise proportions added to the signals of the carrier frequencies. The resulting noisy signals and non-noisy signals of the carrier frequencies are transmitted by a transmission device, and a response signal sent back by a radio device to be tested is received by a receiving device. An analysis device evaluates the received response signal.