Time Domain Measurements for CISPR 16-1-1 EMI Testing: Novel Method to Trace Interfering RF Disturbances

Time Domain Measurements are ideal to trace transient and time limited disturbing RF signals. Modern automotive electronic modules are emitting in some cases strong transient RF disturbances. Such signals are getting critical because comfort options like blue tooth connection, external devices with complex integrated RF functionality (automotive WLAN, UMTS, GSM, WCDMA, MIMO devices, multiband smart phones, Net-books) have to interface with integrated car entertainment and control systems. Due to the technical concept of such wireless communication networks with digital modulation schemes, the interferences are often short events with transient characteristics. The use of WLAN and other wireless services in the area of home applications are a further area of interest. Some home appliances are able to interfere with the wireless communication and need further investigation. Especially critical are disturbances with are not continuous, but connected to the operation mode of the home appliance. To capture such RF signals and to perform reproducible measurements is difficult. Today such measurements are possible using Time Domain Measurement Systems. Those units are equipped with very fast A/D converters, digital filters and calculate in parallel several thousand frequency points using the Fourier analysis.