适用于短波跳频通信的改进型Delta-Sigma调制器

An Improved Delta-Sigma Modulator for Short-wave Frequency Hopping Communications

针对短波通信中跳频技术(FHSS)的随机性、多频率性、瞬时性等特征,提出了一种适用于短波跳频通信的Delta-Sigma调制器,并用于构建频率自适应全数字发射机。在保留低频频谱特性的情况下,将优化过的低通Delta-Sigma调制器(LPDSM)与积分反馈(CIFB)拓扑结构级联,然后利用频率转换技术(FCT)进行变频操作,并根据载波频率实时调整带通(BP)DSM的调制度,调制器产生的高频数字信号将用于驱动高效开关功放。该改进型架构已经通过电路仿真验证,并在现场可编程门阵列(FPGA)中进行了实际电路的物理实现,为实现短波全数字发射机奠定了基础。

According to the characteristics of Frequency-Hopping Spread Spectrum(FHSS)in short-wave communications,such as the randomness,multi-frequency and transience,a Delta-Sigma Modulator(DSM)for short-wave frequency hopping communications is proposed and applied to build a frequency adaptive full digital transmitter.The optimized low-pass Delta-Sigma modulator(LPDSM)is cascaded with the integral feedback(CIFB)topology while preserving the low-frequency spectral characteristics.By using the frequency conversion techniques(FCT),the frequency-conversion operation is performed.The modulation-degree of the bandpass(BP)DSM is adjusted according to the carrier frequency in real time.The high frequency digital signal produced by the modulator will be used to drive a high-efficiency switching power amplifier.The improved architecture is verified by circuit simulation.The physical implementation of the circuit is completed in a fi eld programmable gate array(FPGA).This work lays a foundation to implement all-digital short-wave transmitters.