Measurement method
There are two main methods to measure noise figure: Y factor method and cold source method.
The noise source is an essential equipment for the Y-factor method of measurement. The noise source is a noise generator that can generate two different noise powers. Usually, it needs a DC pulse power supply drive voltage. When the DC drive voltage is supplied, it is equivalent to the noise source being on, which is called a hot state. At this time, a large noise power is output. When the power supply is turned off, it is equivalent to the noise source off, which is called a cold state. At this time, the noise power at room temperature is output. For a given noise source, the value of ENR will change with frequency. According to the different internal attenuators, the nominal value of ENR of typical noise sources ranges from 6 dB to 15 dB. Using the noise source, two noise power measurement results can be obtained at the output port of the device under test. The ratio of these two measurement results (called the Y factor) can be used to calculate the noise figure: NF=ENR-10lg(Y-1), and ENR is generally given by the specifications of the noise source.
Please see the “Manuals/Guides” section of this page for more detailed information.