Re: [Discuss-gnuradio] Offset Problem with UHD and USRP LFTX

[Josh Blum]

> The settings on the USRP source block and the UHD source block in the
> newer GRC version are the same.  The difference is there are a couple
> of extra parameters in the new UHD block that I just leave as default
> (for instance the bandwidth, etc).  Is there a reason I am seeing
> this offset with the newer version which uses the UHD block?  I'm
> wondering if I need to specify additional parameters in order to make
> it act like the USRP source block from the older version?
> 

Hi Tom,

There was a recent change to disable automatic DC offset correction on
the LFRX board since it seemed to give a lot of folks a hard time. In
any case, I think merits a GRC options for the offset correction.

In the meantime try adding my_usrp_souce.set_auto_dc_offset(True) to the
generated python code. Does that work for you?
http://gnuradio.org/cgit/gnuradio.git/tree/gr-uhd/include/gr_uhd_usrp_source.h#n302

I suppose that you could do the equivalent operation (of what the FPGA
is doing) in software with a subtract block and an average block with a
nice long averaging time. :-)

-josh