FAQs from Rohde & Schwarz

Time Domain Scan without Autoranging


When Time Domain Scan is ON, it is not possible to use autoranging. Is there anything I should take into consideration without autoranging?


In general, there is no 100% guarantee for an overload-free measurement even if Autoranging is switched on. For example, there is no overload indication for preamplifiers in front of the preselector (e.g. external amplifier or ESU-B24).

Even if Autoranging is ON, you have to check the measurement values. With Time Domain Scan ON and Autoranging OFF, more observation is needed. Because of the fast scan rates it is difficult to assign the overload indication to specific frequencies.

We recommend the following solution:

If an overload is displayed while Time Domain Scan is ON, we recommend you to restart the measurement with more input attenuation. Please do not forget that the ESU will be less sensitive in the case of higher attenuation.

Another solution is to perform a manual final measurement and judgment at the highest emission levels. But for this measurement and judgment the ESU (and other Rohde & Schwarz EMI receivers) offer an automatic mode, i.e. 'Semi-Interactive'. An appropriate threshold (Margin) can be used as well.