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零中频接收机及其AGC方法的研究与实现
丁丹,刘风亮
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(装备指挥技术学院光电装备系，北京101416;装备指挥技术学院装备指挥系，北京 101416)

摘要:

实现了基于LT5506下变频器和Cyclone IV FPGA的零中频接收机，采用射频、基带一体化架构，尺寸仅为8 cm×6 cm×1.5 cm，重量仅为45 g，功耗仅为 800 mW，满足小型化、低功耗的要求。针对零中频接收机中射频信号检波困难和传统AGC的调节时间受输入信号幅度影响的缺点，由Cyclone IV完成信号检波，增加对数运算环节并改进环路滤波器的结构，配合LT5506中的可变增益放大器仿真并实现固定调节时间的AGC，用8 MHz采样时钟对 1 MHz正弦波进行幅度控制，调节时间恒定为53 μs，不受输入信号幅度影响。

关键词: 无人机测控链路零中频接收机自动增益控制调节时间

DOI：

基金项目:

Study on and Realization of Zero IF Receiver and its AGC Algorithm

DING Dan,LIU Feng-liang

(Department of Optical and Electronic Equipment, Academy of Equipment Com mand & Technology,Beijing 101416,China;Department of Equipment Command,Academy of Equipment Command & Technol ogy, Beijing 101416,China)

Abstract:

The zeroIF receiver based on LT5506 and Cyclone IV is realized. The framework integrating RF and IF is adopted, and the size is only 8 cm ×6 cm×1.5 cm, the weight is only45 g,and the power consumption is only 80 0 mW.The dema nd of small size and low power consumption is satisfied. Aiming at the difficult y of amplitude dete ct for RF signal and the problem that the settling time of traditional Automati c Gain Control(AGC) is af fected by the amplitude of input signal,the amplitude detect is accomplished in Cyclone IV,logarithm operation is added and the structure of the loop filter i s improved,the AGC with fixed settling time is simulated and realized with the cooperation of variable gain amplifier in LT5506,when the amplitude of 1 MHz sine wave is controlled with 8 MHz sampling clock,the settlin g time remains 53 μs,independent of the amplitude of input signal.

Key words: unmanned aerial vehicle(UAV) TT&C link zero IF receiver automatic gain control(AGC) settling time