Signal to Noise Ratio
- The ratio between a recorded signal and spurious background noise. Background noise is most commonly present due to wires and instrumentation reacting to electro-magnetic emissions from surrounding electrical equipment e.g., are welders, vehicle ignition circuits, machine tools. The signal-to-noise ratio is the ratio between the coherent and the noncoherent power at the output.
- The larger the number the better.
- The signal to noise ratio is defined as:
- The larger the number the better.
- where
- γ2 = coherence between input and output signals
- In audio systems the signal to noise ratio is often defined as:
- In audio systems the signal to noise ratio is often defined as:
- where
- SNR = signal to noise ratio [dB]
- The following table gives some typical devices and their associated signal to noise ratio.
- The following table gives some typical devices and their associated signal to noise ratio.
Audio device SNR (dB) Plain Old Telephone System (POTS) 40 AM Radio 50 LP Records 50 Cassettes 70 FM Radio 70 Instantaneous Human Hearing Range 85 CD Player 90 Studio Recording Equipment 120 Total Human Hearing Range 120
