Estimation Technique And Synchronization Methods Of The Sine Non-linear Chirp Keying

Unlike various estimation techniques for the non-linear frequency modulation,parameters evaluation methods for the Sine Frequency Modulation(SFM)are limited.Due to the imperfections of the existing methods,only a few part rather than all of parameters can be evaluated.In this paper theoretical Cramer-Rao lower bound were deduced and a fast estimation method was proposed.Then,since estimation techniques for SNCK is rare,the estimation methods for the time-bandwidth product were analyzed.Based on the Cramer-Rao lower bound of SNCK signals,the time-bandwidth product was evaluated by using the Carson Rule,Discrete Phase Transform and Fractional Fourier Transform,respectively.The simulation results showed that the Carson Rule performed better than other approximated methods and the Carson Rule can estimate parameters with comparably small computational complexity.Moreover,parameters estimation results by the FRFT were compared with other methods.It is known that classical synchronization only can improve its performance by increasing the sampling frequency and the corresponding synchronization signals need to be added to each frame signals.In order to improve the transmission efficiency,a FRFT-time combination self-synchronization with SNCK as its synchronization signals was proposed in this paper.The performance was shown by simulation as well.The results show that this kind of synchronization method can lower the bit error rate and need less extra information bit stream,which can realize rate synchronization of the SNCK communication system and improve the communication efficiency.However,the accuracy of the synchronization signals were affected by the frequency offset and time offset,which means that modulation parameter variations do not have the proportional relations with the relative error.