Quantise

Quantise refers to the process of restricting a continuous range of values to a smaller, discrete set of values. This means that instead of a value being able to take on any point within a given range, it can only assume specific, predefined values. Imagine a dimmer switch that can only be set to specific brightness levels (e.g., 10%, 20%, 30%) instead of smoothly adjusting to any point in between. This is an example of quantisation.

In digital signal processing, quantisation is a fundamental step in converting analog signals into digital ones. An analog signal has a continuously varying amplitude. To represent this digitally, the amplitude must be measured and then assigned to one of a finite number of discrete levels. The number of levels available is determined by the number of bits used in the digital representation. For instance, an 8-bit system can represent 2^8 = 256 different amplitude levels. The difference between the actual analog value and the closest discrete digital level is called quantisation error or quantisation noise.

Quantisation is also a crucial concept in quantum mechanics. In this context, it refers to the idea that certain physical properties, such as energy, momentum, or electric charge, do not vary continuously but exist only in discrete amounts or "quanta." For example, light is composed of discrete packets of energy called photons. This quantisation of energy was a revolutionary idea that helped explain phenomena that classical physics could not.