SNRdB

SNRdB is the signal-to-noise ratio expressed in decibels. It is used across fields such as communications, audio engineering, and instrumentation to quantify how much stronger a signal is than the accompanying noise within a defined bandwidth.

The standard definition uses power. SNRdB = 10 log10(P_signal / P_noise), where P_signal is the average signal power and P_noise the average noise power in the measurement bandwidth. In contexts where voltages or amplitudes are measured with the same impedance, the ratio of voltages can be converted to decibels as 20 log10(V_signal / V_noise); both expressions describe the same underlying quality when applied consistently.

Interpretation: a higher SNRdB indicates a cleaner, more detectable signal. A value of 0 dB means equal signal and noise powers; negative values indicate noise dominance. SNRdB is influenced by bandwidth and noise density, so comparisons should specify the bandwidth and measurement method. In digital communications, higher SNRdB typically yields lower error rates, while in audio it relates to dynamic range.

Typical ranges vary by domain. Consumer audio equipment may advertise SNRs around 90–100 dB; wireless and radio links can span from about 10 dB to more than 40 dB depending on environment and system design. SNRdB is a key factor in system design, influencing link budgets, receiver sensitivity, and overall performance.

SNRdB is a fundamental metric for assessing and comparing signal quality across systems.