# SNR - Signal to Noise Ratio Signal-to-noise ratio (SNR) is defined as the power ratio between a signal and background noise. It is normally measured in decibels (dB). ^ dB value ^ Description ^ | < 6dB | Poor. No sync, or intermittent sync problems. | | 7dB - 10dB | Fair. Vulnerable to conditions. | | 11dB-20dB | Good. | | 20dB-28dB | Very good. | | 29dB < | Excellent. |