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为了正确评价在宇宙通讯等中用的微波低噪声接收机的噪声特性或精密计量宇宙噪声,等效噪声温度是已知的低噪声源必不可少的。以精密测量这些噪声源的等效噪声温度的技术研究为目的,业已研制出了从3700到4200兆赫的宇宙通讯带的极低温标准噪声源和采用液氦冷却微波装置的高灵敏噪声比较测量装置。由于重新把这个噪声比较测量
In order to properly evaluate the noise characteristics or precision cosmic noise of microwave low noise receivers used in space communications and the like, it is indispensable that the equivalent noise temperature is a known low noise source. For the purpose of precise technical research on measuring the equivalent noise temperature of these noise sources, extremely low-temperature standard noise sources of the cosmic communication band from 3700 to 4200 MHz and highly sensitive noise comparison measuring devices using liquid helium-cooled microwave devices have been developed . Because of this noise comparison measure