You can request that UHD tries to get the LO offset you request as close as possible, but because the LO synthesizers used on the USRPs/daughterboards (what are you using, by the way?) can only synthesize a discrete set of frequencies, not everything is possible. Now, I just realized you tried to tune a daughterboard to 3MHz (I misread and thought you'd try to tune to 3GHz). There's no daughterboard that goes that far down, because that's really just baseband. So I have to assume that you're using LFRX or BasicRX, which don't have mixers, so the LO frequency is always 0 and the digital shifting is always the center frequency you ask for.
Best regards, Marcus On 06/05/2015 12:20 AM, John Petrich wrote: > > Marcus, > > > > Yes, could you help me with a specific command for the properties > field: I want a rx frequency of 3.545 MHz with an LO offset of 50e3 Hz. > > > > Thank you, > > John Petrich > > > > *From:*Marcus Müller [mailto:[email protected]] > *Sent:* Thursday, June 4, 2015 2:41 PM > *To:* John Petrich; GNURadio Discussion List > *Subject:* Re: [Discuss-gnuradio] Move USRP LO with USRP sink block? > (was: Re: question per your 2/10/15 post on Ruby Forum) > > > > Hi John, > I'm a bit confused; which discussion is this from? > Ruby-Forum is not actually the platform we use, they just "mirror" the > GNU mailing list archives (I don't really know why they do that -- we > don't have anything to do with them). I'd recommend joining that > mailing list personally [1]. > > Regarding your question: > 10kHz is very small. Possibly, the closest possible physical LO > frequency is still the one you'd have if you didn't shift. Try > increasing 10e3 to something that is out of the band that you want to > observe; for example, if you're using a sampling rate of 10e6, try > 11e6. The only important thing is that the whole observed band stays > within the analog bandwidth of your USRP (B2x0) or the daughterboard > used (modular USRPs). > > Best regards, > Marcus > > [1] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > On 06/04/2015 11:26 PM, John Petrich wrote: > > Marcus, > > > > I cannot get the DC component to shift using this command in the > USRP _Source_ block properties: uhd.tune_request(3.545e6,10e3) > What am I missing? > > > > Thank you in advance, > > John Petrich > > > > *Re: Move USRP LO with USRP sink block?* > <https://www.ruby-forum.com/topic/6873252#1167936> > > D17685d174fee4ca258c75cce7bc2202?d=identicon&s=25Marcus Müller > (Guest) > > on 2015-02-10 20:10 > > (Received via mailing list) > > Well, you nearly already are doing this! > > just use "uhd.tune_request(...,...)" where you'd set the TX frequency > > normally in the USRP sink's properties dialog. > > > > >
_______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
