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本文介绍一种直接变频无线电接收机。与一般超外差式接收机相比,其特点为假信号响应少得多,而且能做成单片集成电路的形式。设计中遇到的主要问题,在于需要一个准确的两相可调本地振荡器。本文还介绍了一种使用伺服控制移相网络的电路;在66～95兆赫频段,两个输出的相位差为90°±2°。本文介绍了完整的调幅及单边带接收机,并探讨了自动增益控制的问题。实验证实了所预期的、能相对地抗御假信号响应的特性。
This article describes a direct conversion radio receiver. Compared with the general super-heterodyne receiver, which is characterized by much less fake signal response, and can be made into a monolithic integrated circuit form. The main problem encountered in the design is the need for an accurate two-phase adjustable local oscillator. This article also describes a circuit that uses servo-controlled phase shifting networks; the phase difference between the two outputs is 90 ° ± 2 ° in the 66-95 MHz band. This article describes the complete AM and single sideband receiver, and discusses the issue of automatic gain control. Experiments confirmed the expected characteristics that are relatively immune to glitch responses.