摘要
对Chirp信号的常用估计方法是Wigner分布峰值(Wigner Distribution Maxima,WDM)法,但在低信噪比情况下,Wigner分布(Wigner Distribution,WD)峰值往往偏离真实值造成瞬时频率(Instantaeous Frequenty,IF)估计误差大。文中提出了一种基于改进WD的多分量Chirp信号瞬时频率估计方法——Wigner Viterbi拟合法(Wigner Viterbi Fitting,WDVF)法。该方法将信号的WD作为图像,运用Viterbi算法分离出多分量Chirp信号的各个信号分量,再估计出各个分量的瞬时频率。新方法的估计精度高,在低信噪比情况下性能明显优于WDM法,并且WDVF法能较好地抑制时频交叉项与边缘效应。仿真结果表明,在信噪比为-15^-8 dB时,与WDM法相比,WDVF法的瞬时频率估计均方误差能减少约50%,具有良好的工程应用价值。
Aim. Under certain conditions, the Wigner distribution maxima （WDM） method gives inaccurate estimation of the IF of multi-component Chirp signal. We now present a new Wigner distribution Viterbi fitting （WDVF） method that can estimate such IF with much higher precision. In the full paper, we explain the WDVF method in some detail; in this abstract, we just add some pertinent remarks to listing the two topics of explanation. The first topic is： the WDM method of IF estimation. In this topic, we point out that IF estimation errors increase because the WDM often deviate from their true values if the signal to noise ratio （SNR） is low. The second topic is： the IF estimation method based on the WDVF method. Under this method, we transform the Wigner distribution of the Chirp signal into digital image and apply the Viterbi algorithm to separating the multi-component Chirp signal into individual-component signals. Then we carry out the linear fitting of the individual components thus separated and obtain their IFs estimated by the WDVF method, as shown in Fig. 3（c） in the full paper. Finally we simulate and analyze the performance of the WDVF method by comparing it with the WDM method. The simulation results, shown in Fig. 4 in the full paper, indicate preliminarily that the WDVF method reduces considerably the IF estimation errors under low SNR and effectively suppresses the time- frequency interference items and edge effects. Its performance is better than the WDM method, especially under low SNR. When SNR is -15 dB to -8 dB, the WDVF method can reduce the mean square error by approximately 50% compared with the WDM.
出处
《西北工业大学学报》
EI
CAS
CSCD
北大核心
2008年第1期83-87,共5页
Journal of Northwestern Polytechnical University
基金
国家自然科学基金(60572098)
航空基金(05F53027)资助
