Definition of analog-to-digital

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Photonics Dictionary

analog-to-digital: Analog-to-digital (A/D) is a process that converts continuous analog signals into discrete digital signals. This process coverts analog signals continuously, which vary smoothly over time, into a digital form that can be used by digital devices. This process involves two main steps:

Sampling: The analog signal is sampled at regular intervals. The frequency at which the signal is sampled is called the sampling rate or sampling frequency. According to the Nyquist theorem, the sampling rate must be at least twice the highest frequency present in the analog signal to accurately reconstruct the original signal from its samples.

Quantization: Each sampled value is then quantized, which means it is assigned to the nearest value from a finite set of discrete levels. This process introduces a small amount of error called quantization error.

Key components and concepts:

Sampling rate: Determines how often the analog signal is sampled per unit of time (e.g., samples per second, or Hertz).

Resolution: Refers to the number of discrete values (quantization levels) that the ADC can produce. It is often expressed in bits, with a higher number of bits indicating a higher resolution and more precise representation of the analog signal.

Quantization: The process of mapping a range of analog signal values to a discrete value. It involves rounding the sampled values to the nearest available digital level.

Analog-to-digital conversion is essential in various applications, including:

Audio recording and processing: Converting analog audio signals into digital form for storage, editing, and playback.

Telecommunications: Digital transmission of analog voice signals.

Medical equipment: Converting signals from sensors into digital form for processing and analysis.

Instrumentation and measurement: Digital representation of analog sensor data for monitoring and control systems.