USRP drivers vs UHD drivers in gnuradio-companion

GNU Radio
1

After successfully installed uhd and gnuradio from the next branch on
F13 i run a simple gnuradio-companion test with a flex 1800 as the
source and an FFT sink.

It seems that when i use a uhd source my signal is ~ 80dB lower than
when using a USRP source. What is the explanation of this?

Also, it used to be that I needed to be in the “usrp” group in order to
access the USRP.
Now i deleted this group and i still have access to usrp (even when the
source is not a uhd one but a usrp source)!
My understanding is that if i use the uhd device then i can do that
(ie, don’t need to be in the “usrp” group) but it seems to be happening
even with the usrp source.
What am I missing?

Thanks
Achilleas

2

After successfully installed uhd and gnuradio from the next branch on
F13 i run a simple gnuradio-companion test with a flex 1800 as the
source and an FFT sink.

It seems that when i use a uhd source my signal is ~ 80dB lower than
when using a USRP source. What is the explanation of this?
In “traditional”, samples were in the -32K to +32K range, but under UHD,
complex samples are in [-1, 1]. Just a scaling issue.

Merely deleting the “usrp” group from group file doesn’t do anything
until you log-out/log-in again.

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium