BER is calculated by comparing the transmitted sequence of bits to the received bits and then counting the number of errors. In this application note, you will learn how the Tektronix OM4225/4245 Coherent Lightwave Signal Analyzer enables access to the complete set of variables for characterizing complex optical signals on. Bit Error Ratio Tester is an instrument used to test and analyze bit error ratio in digital transmission systems, fiber optic communication systems, and digital microwave communication systems. Through the interpretation of actual test reports, it. One of the most important ways to determine the quality of a digital transmission system is to measure its Bit Error Ratio (BER). The BER measurement helps in assessing the quality.