在基于脉冲计数的外差干涉信号处理中，提出了一种零相位差跳变补偿的大小数相位结合处理方法，可实现外差干涉信号处理中大小数的准确结合。大数测量采用对两路干涉信号进行脉冲计数同步对减的方法实现，小数测量采用混频降频方法来提高测量分辨率，并采用锁相环对拍频信号跟踪产生用于混频降频的动态基准信号，解决外差信号拍频变化的问题，以提高小数测量分辨率的稳定性。基于信号发生器对实现的外差干涉信号处理方法进行了验证，包括测量精度、大数计数、小数相位测量。构建了双通外差干涉位移测量光路，通过对精密导轨位移的测量来验证大小数结合处理方法的有效性和信号处理方法在外差干涉位移测量应用中的可行性。

A zero phase difference jumping compensation processing method for heterodyne interferometric signal processing based on pulse counting is proposed, which can guarantee the correction integration of measured integer and fraction phase. The integer phase measurement is realized by counting pulse numbers of two interference signals and synchronously subtracting. The fraction phase measurement is realized by frequency mixing and frequency reduction to improve the measurement resolution. A dynamic base signal is generated by tracking the reference interference signal with phase-locked loop and the signal is used for frequency mixing to solve the problem of frequency changing of heterodyne interference signals. This method can improve the resolution stability of fraction phase measurement. The verification experiments are done with a function generator，including phase measurement precision, integer counting and fraction phase measurement. A two-pass heterodyne interferometric optical layout is constructed for displacement measurement experiments, the displacements of precision stages are measured to verify the effectiveness of the proposed compensation method for integration of integer and fraction and the feasibility of the implemented signal processing method in actual heterodyne interferometric displacement measurement.