Accurate frequency estimation of real sinusoid signal

Using the maximum likelihood estimation, the accuracy of frequency estimation can reach Cramer-Rao lower bound(CRLB) for a single complex sinusoid signal, but for the real sinusoid signal, accuracy can not reach CRLB, the reason is that real signal frequency spectrum include negative frequency, in addition, window function cause leakage of negative frequency spectrum, thus affecting the positive frequency part. In this paper, using Kaise window to reduce the effect of the leakage of negative frequency, to improve the estimation accuracy, estimation accuracy can be close to CRLB. And for multiple frequencies estimation, Kaise window can also reduce interaction effect of the frequency spectrum leakage, the computer simulation results show that this method is effective.