Using amplitude modulation and frequency modulation transceivers as an object of study, a precise modeling of the nonlinearity of front-end low noise amplifier of the co-site receiving station was presented, the interference suppression requirements for the amplitude modulation and frequency modulation radios were analyzed, and the analytical model was verified by numerical simulation. The results show that the proposed analytical model is more accurate than the existing ones. In addition, when the interference power, the useful signal power and the noise power are the same, the requirement of interference suppression of the amplitude modulation communication system is higher than that of the frequency modulation communication system.