FAQs from Rohde & Schwarz

RTO-K11 IQ Software Interface shows "CF+BW/2 > DevBW"

Question

I am using the IQ software interface of my RTO. When I set the carrier frequency and the filter bandwidth I get the warning CF + BW/2 > DevBW. The bandwidth of my RTO is 6 GHz. The carrier frequency is 20 MHz and the filter bandwidth 1.6 GHz (see screenshot). The result of the formular is 820 MHz which is not bigger than 6 GHz. What is the error?

Warning: CF + BW/2 > DevBW

Answer

Please check the impedance setting of the channel you are using. If the impedance is 1 MOhm (default setting if no probe is connected) the bandwidth of that channel is just 500 MHz. Set the impedance to 50 Ohm, then the warning is gone.