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


jdow
 

Is it possible that flexing the antenna cable makes and breaks the direct contact to the center conductor hole in the FCPP's RF input? The only other thing that comes to mind is that somehow it is being treated as an audio device and the audio mixer distinguishes it differently on the two different USB sockets giving it a different gain setting.

{^_^}

On 20191221 17:26:32, Rick Hall wrote:
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


Stu C <stu@...>
 

The Funcube acts as a sound card, have you checked the recording levels (with any "boost") while plugged into the two sockets?
Cheers
Stu


Rick Hall
 

jdow,

 

Windows treats the FunCubePro+ as an audio device… And Windows gives the same device a unique (i.e. different) name associated with each different USB port.    Windows had managed to set the levels differently for the two ports.   Probably never would have found it without your help.  

 

Side note:  I plan to put the FunCube in a larger metal box with a short jumper inside it to a chassis mount N connector to deal with the mechanical deficiencies of the SMA connector in a ‘dynamic’ application… Where the computer is moved around… antennas are changed… lots of pulling and flexing that the SMA and small coax don’t deal with very well.   Also adding an A to B adapter with a short jumper between the box and the computer.

 

Thanks and 73, Rick – K5GZR

 

 

SDRC with FunCubePro+ S-meter shows 20 dB difference between two USB ports on same computer
From: jdow
Date: Sat, 21 Dec 2019 22:58:33 PST

Is it possible that flexing the antenna cable makes and breaks the direct contact to the center conductor hole in the FCPP's RF input? The only other thing that comes to mind is that somehow it is being treated as an audio device and the audio mixer distinguishes it differently on the two different USB sockets giving it a different gain setting.

{^_^}