一、概述测量接收机的噪声系数,通常是用气体放电管噪声发生器或二极管噪声发生器作为信号源,在被测接收机的检波器输出端用附加的电流或电压表来测量检波电流或电压,作为输出噪声功率的指示仪表。但是,检波器对不同大小的输入信号有不同的反应:小信号时呈平方律检波;大信号时呈线性律检波;中等信号时处于两者之间。由于检波规律的不同,会使测得的噪声系数有较大的误差。如能有一个精密的衰减器来改变信号的大小,使测量噪声系数的过程中,保持检波器的输入信号大小不变,则因为检波规律相同,就可以避免由检波规律 First, an overview Measuring the noise figure of the receiver, usually with a gas discharge tube noise generator or diode noise generator as a signal source, measured receiver receiver output with additional current or voltmeter to measure the detection current or Voltage, as an indicator of output noise power. However, the detector responds differently to different sized input signals: square-law detection for small signals; linear-law detection for large signals; and intermediate signals for both. Due to the different detection rules, the measured noise figure will have a greater error. If you can have a sophisticated attenuator to change the size of the signal so that the measurement of the noise figure in the process of maintaining the same size of the input signal of the detector, because the detection of the same law, you can avoid the detection law