Radio Frequency Noise

Although there are many different types of noise, there are many aspects of noise that are common across all types along with the various forms of description.

Noise by its very definition is random. It extends in various forms across the frequency spectrum, although not always in the same amplitude. Accordingly there are different categories of noise according to the frequency distribution:

• White noise: White noise is the type of noise that affects all frequencies equally. It spreads up from zero frequency upwards with a flat amplitude. It gains its name from the fact that white light contains all colours, and hence frequencies equally, and white noise contains all frequencies of interest equally.
• Pink noise: Pink noise gains its name from the fact that it does not have a flat response - it contains some frequency bands more than others. With pink noise, the power density falls with increasing frequency. It gains its name because red light is at the lower end of the light spectrum - its power density is biased towards lower frequencies, so to with pink noise where its power density is biased towards the lower frequencies.
• Band limited noise: Noise can have its frequency band limited either by filters or the circuit through which it passes.