The IEEE 802.3 identifies several compliance tests to ensure equipment interoperability. Many of these tests are performed using a digital storage oscilloscope and an arbitrary waveform generator. Media dependent interface (MDI) return loss is among the most crucial tests that typically have been performed by using a vector network analyzer, thereby implying additional resource requirements.

Recent development of Ethernet compliance test software for Tektronix’ TDS7000 series oscilloscopes incorporates a test fixture combined with AWG, signal source, and differential probes that enables the oscilloscope to perform the required differential return loss measurement. In addition, a patent application is in process for this system. The software application on the oscilloscope compares the return loss results against the IEEE 802.3 limits and generates the desired reports. This paper describes the test and measurement setup and the theory behind this new system that enables efficient use of resources and shorter validation cycles.