Included in at least one reviewed higher-education syllabus.
S4-5.4 Noise
You can characterise thermal, white and colored noise, compute noise figure and equivalent noise temperature, and analyse cascaded systems.
Noise is the physical enemy every communication system is designed against, and this topic gives it a mathematical costume: white, colored, thermal, and the additive white Gaussian noise model. Noise figure and equivalent noise temperature are two currencies for the same quantity — how much a component degrades signal to noise — and converting between them is routine professional arithmetic. The cascade formula carries the unit's practical wisdom: the first stage of a receiver dominates the total noise, which is exactly why low-noise amplifiers sit at the antenna rather than at the desk.
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Thermal noise, white noise, colored noise, AWGN
Noise is the physical enemy every communication system is designed against, and these are its standard mathematical costumes. Thermal noise comes from the motion of charge in any resistor, and the additive white Gaussian model is the default assumption of the field.
Noise temperature
Noise temperature restates a component's noise as the temperature a resistor would need to produce the same amount. It is a convenient currency because it makes noise from different sources directly addable.
Noise in a two-port network: noise figure, equivalent noise temperature, noise bandwidth
Noise figure says how much a component degrades the signal-to-noise ratio passing through it, and noise bandwidth is the equivalent ideal band it acts over. These are the numbers on the datasheet of every receiver component.
Noise figure and noise temperature for cascaded systems
In a chain of amplifiers the first stage dominates the total noise, because everything after it is divided by the gain in front. That single result is why a low-noise amplifier sits right at the antenna, and it is the practical wisdom of the unit.
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