A method, a signal generator, an appliance for a mobile radio system, and a measurement system are provided. First of all, a signal generator generates signal data. The signal data are used to generate a signal which is sent to the appliance which is to be tested. The appliance which is to be tested receives the signal and evaluates it. The evaluation of the received signal is taken as a basis for generating a response signal, wherein the response signal has an envelope which is characteristic of the information which is to be returned. This characteristic envelope is measured and a measurement signal which is representative thereof is generated. The measurement signal is supplied to a correlator in the signal generator and is compared with a comparison signal stored in the signal generator.