The ML4039B is a fully featured 200G Bit Error Rate Tester. It has instrument-grade 2.92 mm coaxial connectors and covers a wide range of bitrates between 1.25 and 29 Gigabaud, while supporting both NRZ and PAM4 encoding schemes.

The GUI supports individual control of each TX level, equalization, eye balance, and pattern selection. The user may also inject error sequences into the stream. The receiver features CTLE and FFE equalization that, in combination with TX FFE, compensates for up to 30 dB of loss at Nyquist. It also enables advanced debug capabilities by showing separate LSB and MSB BER, offering targeted error-insertion and allowing real-time monitoring of the received signal histogram level, signal-to-noise ratio and receiver equalizer tap values.