What is a good signal-to-noise ratio?

Understanding Signal-to-Noise Ratio (SNR)

Signal-to-Noise Ratio (SNR) is a critical measure in the field of optical engineering, as well as in various other disciplines such as audio engineering, telecommunications, and data communications. It quantifies the level of a desired signal to the level of background noise. SNR is usually expressed in decibels (dB). A higher SNR indicates a cleaner, clearer signal.

What Constitutes a Good SNR?

A good SNR varies depending on the application. However, generally:

  • For high-fidelity audio applications, an SNR above 90 dB is considered excellent.
  • In data communications, an SNR above 20 dB is typically necessary for reliable transmission.
  • Optical systems, such as fiber optic communications, aim for an SNR of 30 dB or higher for optimal performance.

It's important to note that the required SNR can greatly depend on the specific requirements of the system or application. For instance, critical applications such as medical imaging or satellite communications may require even higher SNR values to ensure accuracy and reliability.

Calculating SNR

SNR is calculated using the formula:

SNR (dB) = 10 * log10(Psignal / Pnoise)

Where Psignal is the power of the signal and Pnoise is the power of the noise. This formula provides a logarithmic measure of the ratio of signal power to noise power, allowing for easier comparison of very large or very small ratios.


In conclusion, a good SNR is essential for ensuring the quality and reliability of a system's performance. While the definition of a 'good' SNR can vary, understanding and achieving the optimal SNR for a given application is a fundamental aspect of optical engineering and related fields.

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