Thanks Ian for your answer; but my main question still remains unanswered which is why with different wire format sc8 and sc16 the spectrum is different? How may I interpret this?
Thanks, > On Jun 25, 2018, at 9:44 PM, Ian Buckley <i...@ionconcepts.com> wrote: > > On a USRP2 thats a harmonic of the on-board 100MHz clock. One excellent way > to deduce when you are dealing with a spur thats LO related is to use offset > tuning to move the LO relative to the center of your band of interest. > See: https://files.ettus.com/manual/structuhd_1_1tune__request__t.html > > >> On Jun 25, 2018, at 3:15 PM, Farhad Mirkazemi via USRP-users >> <usrp-users@lists.ettus.com> wrote: >> >> Hi all, >> >> I attached the two spectrum snapshots with no antenna connected (which means >> what I'm seeing is just pure noise?)to usrp2 setting the center frequency at >> 1590 MHz, one using sc16, fs 25 MHz and the other sc8 wireformat fs 50 MHz; >> regardless of the spike at 1600 MHz (10 MHz off the fc) which I don't know >> why it shows up on both spectrum (I can interpret the spike at the center >> frequency as dc component but don't know about this one); so it looks like >> for the sc8 the spectrum has been folded around center frequency where for >> sc16 wireformat it looks normal. can you please explain why is that and how >> to fix this? >> >> Thanks, >> >> >> >> >> On Friday, June 22, 2018, 5:52:23 PM EDT, Marcus D. Leech via USRP-users >> <usrp-users@lists.ettus.com> wrote: >> >> >>> On 06/22/2018 05:43 PM, Farhad Mirkazemi via USRP-users wrote: >>> >>> Hello all, >>> >>> I'm recording RF signal at 1.5 GHz using usrp2 with wbx daughterboard of >>> fixed BW of 40 MHz; since I'm interested to capture the whole BW, I set the >>> over-the-wire format to sc8 to be able to have 50 MSps rate; as example >>> rx_samples_to_file suggests, there is no "byte" or "char" format to store 8 >>> bit IQ samples; now, if I use "short" type and try to read my binary file >>> using matlab, for example, and use the same "int16" format as I was doing >>> for SC16 wireformat, i.e interpreting it as I1, Q1, I2, Q2 ..... using >>> "int16" reading format, the spectrum looks not the way it should. I know it >>> also has to do with the host cpu format which in my case it is 64 bit >>> processor but I don't know how to manage the transformation between the >>> host and the packet router. Can some please explain how it works and if >>> possible how to interpret the data on platform other than uhd? it is also >>> appreciated if explain how I could store using 8 bit format >>> so that the file size be reduced to half. >>> >>> Thanks, >>> >>> >> You may need to tweak the dynamic range in the device arguments, using >> "peak=0.01" or even "peak=0.001", depending on hows strong your >> signal is. >> >> Also, could you describe what you mean by "not what it should be" ?? That's >> a little vague. >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> <Screenshot from 2018-06-25 17-58-12.png><Screenshot from 2018-06-25 >> 18-00-34.png>_______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
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