EMI receiver from Rohde & Schwarz offers real-time analysis
Martin Rowe - August 7, 2012At the 2012 IEEE EMC Symposium, Rohde & Schwarz introduced the Model ESR EMI Test Receiver, which uses FFTs to produce two analysis features that reduce precompliance test time. Because it’s FFT based, the ESR receiver can display an emissions spectrum in real time, without having to wait for a frequency sweep. It can, though, produce a swept-frequency scan for compliance tests that require it.
The ESR receiver also cuts test time by displaying both peak and quasi-peak spectral plots at the same time. Thus, you don’t need to run separate measurements to get both. The video shows how the ESR receiver displays both. In addition, it can compare emissions against test limits set of common EMI standards such as CISPR, EN, ETS, ANSI, FCC and VCCI. The trace on the video covers 150 kHz to 30 MHz. When the quasi-peak signal exceeds the specified limits, the receiver indicates a failure.
The ESR test receiver also displays emissions in spectrogram form. That provides a “third dimension” of a spectral plot. The photo below shows that frequencies such as narrow-band interference appear in colors that indicate a greater occurrence.
Because it also displays a spectral plot over time, the receiver can highlight intermittent signals. Because of that feature, the receiver can display frequencies of signals that are buried below higher-level signals. For example, you can see narrowband signals at amplitudes below that of wideband signals. Tat display can indicate that you have more then one EMI emissions problem.
In another display (below), the ESR test receiver shows frequency over time. In the photo below, a frequency line near the center of the plot shows breaks, indicating that the signal is intermittent.
The Model ESR EMI receiver is available in two models: 9 kHz to 3.6 GHz and 9 kHz to 7 GHz.