中文摘要：

针对chirp信号在分数阶Fourier域上被低于二倍信号频率采样（欠采样）后，仍能恢复原始信号的问题，依据分数阶Fourier域上带限信号的采样定理，分析了分数阶Fourier域上欠采样时应满足的条件，并对其进行了仿真验证。结果表明：对chirp信号进行欠采样后能够得到采样信号的能量聚焦。取不同的调频率，欠采样的采样信号仍能较好地估计出调频率，并能恢复原始信号。

英文摘要：

When chirp signal in FRFT domain is after sub-sampling, the original signal can be reconstructed. For this problem, according to sampling theorem for band-limited signals with FRFT, a certain conditions for sub-sampling in FRFT domain is satisfied. These methods are verified by simulation examples： the chirp signal after sub-sampling can get sampling signal to energy accumulation. Taking different frequency modulation rates, the sampling signal can estimate the rate and the original signal can be reconstructed.