Abstract: A fast carrier frequency offset detection algorithm is proposed for the compass navigation signal，which is implemented by DSP.After the IF signal digital down conversion and decimation，it gets the information of carrier frequency offset with small data quantity and improves computing speed of DSP by fitting arctangent in the numerical method.Computer simulation and actual comparison test show that this algorithm can detect the navigation signal’s carrier frequency offset quickly and precisely，and makes the azimuth information of software radio compass calculation more effective.Compared with the traditional frequency offset detection achieved by simulating the frequency discriminator in radio compass，the proposed method has the advantages of high accuracy，flexible programmability and low cost，and it has some potential for application in the future.

Key words: compass, software radio, frequency offset detection, Intermediate Frequency（IF） digitization

摘要： 提出一种罗盘导航信号载波频差的快速检测算法，并通过DSP芯片实现。在中频导航信号数字下变频和抽样之后，通过拟合的数值方法快速计算反正切，最终完成载波频差信息的提取，降低了数据运算量并保证了DSP计算的实时性。计算机仿真和实际对比测试表明，该算法可以快速准确地检测出导航信号的载波频差，使得软件无线电罗盘解算的方位信息的有效性得到保证。与传统无线电罗盘中通过模拟鉴频器实现频差检测的方法相比，该方法具有精度高、成本低、灵活可编程等优点，有一定的推广应用前景。

关键词: 罗盘, 软件无线电, 频差检测, 中频数字化