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发射机噪声基本指导观点表明,噪声最好以 AM 和 FM 噪声来叙述和测量。知道 AM 和 FM 噪声以后,用计算方法确定 RF 频谱。由 AM 噪声功率谱密度形状来确定 AM 噪声对 RF 频谱的影响。FM 噪声对 RF 频谱的影响是做到 RLC 电路谐振频响曲线的形状,而不是具有边带结构的δ函数。直接用检波二极管进行 AM噪声测量。频率超过5GHz FM 噪声测量是用单端谐振腔体的鉴频器来进行。低于5GHz 的将用一个改进传输线鉴频器进行,以后详细地叙述。可能用注入锁定振荡器作前置放大器接至鉴频器上进行低功率低噪声信号源测量。最广泛使用的基带分析仪是带宽不变的超外差式波或频谱分析仪。用熟悉的基带分析仪来解决测量结果的最大差异。发射机噪声测量的基带频谱分析至少能自动,又很好地节约了时间和改进记录。
The basic guidance of transmitter noise shows that noise is best described and measured in AM and FM noise. After knowing the AM and FM noise, the RF spectrum is computationally determined. The effect of AM noise on the RF spectrum is determined by the AM noise power spectral density shape. The effect of FM noise on the RF spectrum is the shape of the resonant frequency response of the RLC circuit, not the delta function with sidebands. Directly with the detection diode AM noise measurement. Frequency of more than 5GHz FM noise measurement is used single-ended resonator cavity frequency discriminator to carry out. Below 5GHz, an improved transmission line frequency discriminator will be used, described in detail later. The injection lock oscillator may be used as preamplifier connected to the discriminator for low-power low-noise signal source measurement. The most widely used baseband analyzer is a constant bandwidth superheterodyne wave or spectrum analyzer. Use the familiar baseband analyzer to solve the biggest difference in measurement results. Baseband spectrum analysis of transmitter noise measurements can at least automatically and well save time and improve recording.