基于多功能采集卡的2FSK调制与解调

2FSK modulation and demodulation based on Virtual Instruments

利用NI多功能采集卡实现2FSK信号的调制与解调,通过LabWindows/CVI编程实现,充分发挥虚拟仪器“软件就是仪器”的优势。其中解调算法是对过零检测法的改进,不需要传统过零检测法复杂的滤波电路,通过搜索3个参数适用于解调不同频率的2FSK解码,克服了常规解调器只能解调固定2FSK信号的问题。调制算法在已知通信协议的基础上,通过对数据进行编码生成相位连续2FSK信号,利用采集卡的D/A通道定时发送,模拟通信系统的正常通信。本文的算法已经在作者研究的三套通信系统中经过检验,效果较好。

This text uses multifunction acquisition card of NI to accomplish modulate and demodulate of 2FSK. Through programming by LabWindows/CVI, we can see the advantage which is 'Software is Instrument' of virtual instrument. Demodulation algorism is an improvement of zero crossing detection, which doesn' t need complicate circuit. Through searching three parameters to fit for 2FSK decode of difference frequency, the problem that conventional demodulator can only demodulate fixed 2FSK signal is resolved. Modulation algorism is based on the communication protocol which is already known. 2FSK signal of continuous phase is generating by encode data, and then sending 2FSK signal make use of DA clock. The algorism in this article has already tested in three com-munication systems which were studied by author, and the result is fairly good.