What is the highest BER before performance starts to deteriorate?

The highest Bit Error Rate (BER) before performance starts to deteriorate is often cited around 1E-07.5, which indicates that for every 10 billion bits sent, on average, 5 bits may be expected to have errors. At this rate, a system can usually function effectively without noticeable issues.

In telecommunications, a lower BER signifies a clearer signal with fewer errors, leading to better performance and quality. As the BER increases, systems will start to experience degradation in performance since the error-correction mechanisms could become overwhelmed, leading to video glitches in streaming, dropped calls in voice communications, or data retransmissions in network traffic.

To provide context, while values like 1E-09 and 1E-06 represent similarly low rates, they either indicate impractically perfect performance or significant reliability concerns for data rates at which most technologies operate. A value like 1E-05 signifies a much higher failure rate, which would clearly result in unacceptable performance. Thus, the choice of around 1E-07.5 is recognized as a balance between acceptable error rates and system reliability.