Advanced explanation:
SNR (Signal-to-Noise Ratio) is a measure of the quality of a signal in a communication system and is usually specified in decibels (dB). It describes the ratio of the average power of the useful signal.
A high SNR indicates clear signal transmission with low interference, which reduces the bit error rate (BER), especially in digital transmissions, and allows a higher modulation level (e.g. 64-QAM or 256-QAM). Conversely, low SNR can lead to data loss, erroneous transmissions or the need for more robust but less efficient modulation techniques.
SNR is a crucial parameter in almost all communication systems – be it in mobile communications (e.g. LTE/5G), WLAN, radio technology or optical transmissions. In wireless systems, many factors influence the SNR, including distance to the base station, multipath fading, interference and physical obstacles. A typical good SNR value for LTE is around 10 db to 20 dB or more; values below 0 dB indicate a heavily disturbed connection.