The invention discloses a detection method and apparatus. The method comprises: a first frequency signal is received, wherein the first frequency signal is an output signal generated and sent by a first device; the first frequency signal is converted into a second frequency signal, wherein the frequency of the first frequency signal is different from that of the second frequency signal; abd the second frequency signal as a feedback signal of the output signal is transmitted to the first device or a second device, wherein the second frequency signal is used for detecting the first device or the second device. Problems of complicated and difficulty IDU performance or fault detection of the existing microwave system can be solved.