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测量发射机噪声的基本指导观点表明,最好把噪声视为调幅和调频噪声来阐述和测量。当知道了调幅调频噪声,就可通过计算来确定射频频谱。调幅噪声对射频频谱形状的影响取决于调幅噪声的功率谱密度的形状。调频噪声对射频频谱的影响,是RLC谐振响应具有边带结构,而不是δ函数具有边带结构。振幅噪声用直接式检波二极管进行测量。5千兆赫以上频率的调频噪声用单端谐振腔鉴频器进行测量。5千兆赫以下的调频噪声用改进的传输线鉴频器进行测量。对于这种鉴频器,本文将作详细介绍。把注入锁定振荡器作为鉴频器的前置放大器,就可能测量低功率低噪声信号源。广泛使用的基带分析器是具有固定带宽的超外差波形或频谱分析器。通过对基带分析器的了解,可以解决大多数测量结果中的差值。至少发射机噪声测量的基带分析可以自动化,具有节约时间和改进资料提供的价值。
The basic guideline for measuring transmitter noise shows that it is best to interpret and measure noise as amplitude and FM noise. When you know the AM FM noise, you can calculate the RF spectrum. The effect of AM noise on the shape of the RF spectrum depends on the shape of the PSD of the AM noise. The effect of FM noise on the RF spectrum is that the RLC resonance has a sideband structure rather than a delta function with a sideband structure. Amplitude noise is measured with direct detection diodes. Frequency modulation noise above 5 GHz is measured with a single-ended resonator frequency discriminator. FM noise below 5 GHz is measured with an improved transmission line frequency discriminator. For this frequency discriminator, this article will be described in detail. The injection lock oscillator as a preamplifier for the frequency discriminator, it is possible to measure low-power low-noise signal source. The widely used baseband analyzer is a superheterodyne waveform or spectrum analyzer with a fixed bandwidth. By understanding the baseband analyzer, you can solve the difference in most measurements. Baseband analysis of at least transmitter noise measurements can be automated, saving time and improving the value of data provision.