LFM and FRFT to a novel FSK method

With cosine signal as carrier, the traditional Frequency shift keying (FSK) method achieves fast non-coherent demodulation by FFT. But as carrier, the cosine signal has the shortcomings of non-time-varying the signal, fixed frequency, anti-interference and poor security performance. Aiming at these problems, this paper presents a novel modulation and demodulation method, which achieves the fast incoherent demodulation with the linear frequency modulation (LFM) signal as carrier and Fractional Fourier Transform (FRFT). With LFM signal as carrier, that FRFT can be used to achieve rapid demodulation, has been shown in Theoretical analysis and simulation results. In addition, the LFM signal has good performance of anti-interference and confidentiality, compared with the traditional cosine signal as carrier, because it is a time-varying signal, whose time domain and the frequency domain are both changing.