Abstract: The frequency of the radar signal parameters is important，which is useful for the target of screening，identification and classification.There are many digital frequency algorithms.They each have advantages and disadvantages.Generally，they can be divided into time domain frequency and frequency domain frequency.On the basis of the current digital frequency method，this paper for the first time applies the algorithm of subspace rotation unchanged to the study of passive radar frequency.In theory，this paper analyses the feasibility of the algorithm.The simulation proves the effectiveness of the algorithm.

摘要： 雷达信号的频率参数是用于目标筛选、分类和识别的重要参数。数字测频算法有很多种，它们互有优劣，大体上可分为时域测频和频域测频。在对当前数字测频方法研究的基础上，首次将子空间旋转不变法应用到无源雷达数字测频，理论上分析了该算法的可行性，仿真证明了该算法的有效性。