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Picozed SDR 2 Noise Figure

Question asked by hammerclavier on Apr 11, 2017
Latest reply on Apr 11, 2017 by larsc
I have a setup that consists of a Picozed SDR 2 and a FMCOMMS3 that sit on a Picozed FMC carrier board. In this setup 2 instances of axi_ad9361 ip have been used to receive an IQ signals from 9361 chip (RX1) on the picozed board and route them to TX1  side of FMCOMMS3. The purpose is to evaluate the noise figure of the whole system. Here are the parameters of the system:
RF BW : 5MHz
Sampling rate: 20Msps (the ADC sampling rate is set to 8*20=160 Msps)
Rx gain: 70 dB
Tx gain: -10 dB
Cable loss in the system: ~ 1dB
Input signal: Single tone at 1.864 GHz with the power of -63dBm ( the signal does not seem to be clipped).
Measured output power: -39 dBm
Question: Our expectation is that the output signal power is around -4 dBm, but it is instead -39 dBm. Could you please guide us to understand the discrepancy between these two values@?larsc

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