Algorithm 1 FOCC-based Adjacent-Frequency Interference Detection Algorithm

(Step 1) The power of the received mixed signal x(t) is normalized, and the power spectrum is calculated to determine the search range of the cyclic frequency $\alpha$. (Step 2) The FOCC of x(t) is calculated, and its amplitude spectrum for cyclic frequencies $\alpha -|C_{40,x}^{\alpha }(0,0,0)|$ is obtained. (Step 3) A suitable threshold is set to calculate the number of discrete spectral lines in the amplitude spectrum. In this paper, the threshold is set to 0.5 according to the analysis of Equation (7). (Step 4) The adjacent-frequency interference occurs when the number of discrete spectral lines is greater than the number of expected signals; otherwise, there is no adjacent-frequency interference.