[Discuss-gnuradio] found problem with std_4rx_0tx.rbf

[Hans Glitsch]

Hi,

There's a problem with the std_4rx_0tx.rbf in the latest release.  This 
problem did not exist in 3.0.

Please see the attached image.  All four inputs should look exactly the 
same, but there is something wrong with input 0.  It could be that the 
imaginary part of the input 0 signal is getting suppressed.  I don't know.

Here's what I did:  I have a brand new usrp with two basic rx boards.  I 
connected a signal generator to a four way splitter and then connected the 
four way splitter directly to the four usrp inputs.  The signal generator 
was set to 480khz at  -17 dbm.  Then I executed "multi_fft.py -d 100 -f 
500000 -g 0".  The attached screen shot shows the problem with input 0.  If 
I move the signal generator to 520khz, the reflection moves to the other 
side of zero freq.  If I swap cables on input 0 and input 1, the problem 
stays with input 0.

Thanks for your help,
Hans

Screenshot-Multi Scope-2.png
Description: PNG image