π/4-DQPSK快速位同步捕获和跟踪算法

An algorithm of symbol timing rapid acquisition and tracking for π/4-DQPSK signals

为了在π/4-DQPSK解调中能快速实现位同步捕获和跟踪,提出将中频差分检测和同步头捕获跟踪相结合的并行处理方法,根据π/4-DQPSK本身的特点,按照π/4-DQPSK解调中的快速同步捕获和位同步跟踪改进算法,结合信号能量检测、频移初捕并行处理的位定时算法,采用FPGA(fied program grid array)技术实现π/4-DQPSK解调中的快速同步捕获和位同步跟踪。实验结果表明最快可以在8个符号位时稳定恢复时钟同步信号,具有捕获周期短,位定时准确,抗干扰能力强,不受频差影响,适合于高传输码率的跳频通信接收系统应用。

Methods of IF difference detection combined with rapid acquisition synchronization and tracking principle by parallel processing methods were proposed in order to quickly achieve synchronous digital capture and tracking in π/4-DQPSK demodulation. Field program grid array （FPGA） technology to achieve rapid detection of synchronous capture and symbol tracking was adopted by using the improved algorithm in parallel with signal acquisition and frequency offset acquisition. This adoption took into account the characteristics of π/4-DQPSK and was in accordance with the detection of rapid acquisition synchronization and the tracking principle. The experimental results show that clock synchronization signals can be restored stably in eight symbol bit, accurately realize bit-timing, and possess strong anti-interference capability without affecting frequency differences. This proposed algorithm is suited for frequency hopping communication systems with high transmission rates.