基于超外差体系的气象传真机信号接收端设计

Design of the signal reception module of weather facsimile receiver based on super-heterodyne architecture

研究了气象传真机的信号接收和处理问题,针对现有气象传真机射频前端接收模块体型大、功耗高等特点,采用超外差体系结构,根据气象传真机的主要性能指标,进行了硬件电路图的设计和绘制.对射频信号先上变频再下变频,实现了射频放大、选台、滤波、混频等基本功能,完成了射频前端处理模块设计.实验结果表明,该方案尽可能将总增益合理分配到信号处理的各个阶段,避免因放大器一次放大增益过大而引起的振荡,有效完成镜像抑制,满足工程应用需要.

In this paper, the authors discuss the signal reception and processing of a weather facsimile receiver. Aiming at such characters of the present weather facsimile receiver as large reception module at the front RF end and high power consumption, the designed weather facsimile receiver utilizes the super-heterodyne architecture . On the basis of the main performance indices of the weather facsimile receiver, the circuit drawings on hardware are designed and drafted. For RF signal, first the upper frequency conversion is applied, then the lower frequency conversion is conducted, to realize such basic functions as RF amplification, channel selection, filtering and frequency mixing, and complete the design on the processing module at the front RF end. The experimental results show that, in the scheme, the total gain is assigned to each stage in signal processing as reasonable as possible, so to avoid the oscillation caused by overlarge gain amplification of amplifier in one stage, effectively complete the suppression of mirror image and meet the demand in engineering practice.