Noise Factor vs Noise Temperature
Noise Factor
The Noise Factor of a two port network, F, is defined as the ratio of the total noise power density at the output port when the noise temperature of the source is the standard noise temperature (290 K), to that part of the noise power density at the output port which originates from the source at standard noise temperature.
Remember that all the powers are available powers!
Noise Temperature
The IRE definition states that the noise temperature of a two port network is the noise temperature which assigned to the input port of a noise free equivalent of the network yields the saime available output noise power density as the actual network with noise free source.
Noise Temperature may be defined also for a 1-port network (Noise Factor doesn't).
The relation beetween these two quantities is:
F = 1 + Te/T0
where T0=290 K.
You may measure directly noise temperature with a radiometer.
Regards.
References: "Noise Theory", Engberg, Larsen, Wiley