Hello all,
I have an older version of gnuradio (pre 3.6.2) on one of my laptops. When I run a simple script I made in GRC which has a USRP source block and a WAV file sink block it seems to work fine. With nothing connected on the LFRX RF connectors, I get a signal with basically 0 amplitude with 0dB and 10dB gain. This version uses the USRP source block.
On my other laptop I have the newest version of GnuRadio. I made the same exact script using the UHD source block in GRC. When I run this script with the same exact hardware and nothing connected on the RF connector, I get a DC offset in the recorded signal. For 0dB gain, I get basically 0 amplitude, but for 10dB gain I get about -0.05, and for 15dB gain I get about -0.15. This is on a +1/-1 scale.
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?
Thank you,
Tom.