频率测量，LabVIEW图形化编程例程书籍的例程源代码，可以直接使用，或修改部分加入自己的工程，功能稳定。-Frequency Measurement, LabVIEW graphical programming routines routines book source code, can be used directly, or to amend section to be included in their own works, the functional stability.