The difference between the BER achieved by the BER analyzer and the one achieved by the BER test set is that BER test set gives BER on an empirical basis, by dividing the number of bits detected mistakenly by the whole number of transmitted bits. BER analyzer makes the BER calculations on a theoretical basis. That’s why BER analyzer can be more accurate and can give smaller numbers, while the smallest BER the BER test set can achieve is related to the number of transmission bits (for example, if 16384 bits are used, 1/16384 is the smallest BER that can be achieved by this component).