SDRC with FunCubePro+ S-meter shows 20 dB difference between two USB ports on same computer


Rick Hall
 

Using a calibrated level signal source (1.5 microvolts at 145.000 MHz from IFR FM/AM 500) SDRC's S-meter reports a signal strength of about -43 dB when the FCPP is plugged into one of my computer's USB ports, and about -62 dB when plugged into a different USB port on the same computer.   The background noise level shows about the same difference between the two ports.
To switch, I stop the radio, move the FCPP to the other USB port, and start the radio.   Same results if I shut down the computer while making the move between USB ports.   5 year old Dell desktop running Windows 10.   This is a recent condition.  There have been no hardware changes.  It was the same level in either port even after installation of the latest Windows 10 update.  SDRC V3.0.14.
This doesn't seem right.  Can anyone offer some suggestions?
Thanks,  Rick

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