Research on the third-order intermodulation signal characteristic and demodulation product of communication radio

The intermodulation interference of communication radio affect the normal communication, in which the third-order intermodulation interference can not be avoided. In this paper, the signal characteristics of the third-order intermodulation interference are studied, and the envelope expression of the third-order intermodulation products of different modulation styles and the mathematical expression of the demodulator are deduced. The conclusion of the interference source signal characteristics can be obtained using the corresponding demodulation method. The actual test results show that the demodulation of third-order intermodulation products of AM and AM signals cannot demodulate the original signal using envelope detector. The demodulation of third-order intermodulation products of FM and FM signals can demodulate the original signal. The demodulation of third-order intermodulation products of AM and FM signals can demodulate the original signal in a particular situation.