I tried to measure the signal by VSA 89600. I received four channels of signals from the oscilloscope and analyzed them by VSA 89600. In the software, I can set the input signal format to be Single I+jQ or Dual I+jQ. I would like to ask if I use Single I+jQ to measure the signal, does the power displayed in the VSA 89600 need to add 3 dB (Single : I+jQ)? I am confused because I have four channels of signals. What is the difference between Single I+jQ and Dual I+jQ? Thanks.