This is -50dBm from AWG, through 70dB of attenuation.
200Mhz BW limit to limit folding noise from higher frequencies.
So we are talking about a signal of -120 dBm = 224 nVrms = 632 nVpp.
Maybe you could try with the SDS7404A, a proper BW limit set to 60 MHz and 32 Mpts FFT
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