Veghihat, Hope this can help you http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2012-October/005376.html
On Mon, Apr 29, 2013 at 8:24 AM, vegihat vegihat <vegihatd...@gmail.com>wrote: > Well as you advice me, i set the --lo-offset=1M , for the following > command > > uhd_rx_cfile -a serial=4759a751 -N 100000 -f 2.53G --samp-rate=2M > --lo-offset=1M noise.dat -v > > However the peak is still there. I give below the output of > uhd_rx_cfile.py. > As you can see the Rx DDC frequency is -2M (if I have understood > correctly, it should be 1M,right? ) > > Any idea what is the wrong.. > > > linux; GNU C++ version 4.4.5; Boost_104200; UHD_003.005.002-47-g4a860d74 > > -- Opening a USRP1 device... > -- Using FPGA clock rate of 64.000000MHz... > Using mid-point gain of 45.0 ( 0.0 - 90.0 ) > Motherboard: USRP1 (4759a751) > Daughterboard: RFX2400 (no serial, RX2, A:0) > Rx gain: 45.0 > Rx baseband frequency: 2.528G > Rx DDC frequency: -2M > Rx Sample Rate: 2M > Receving 100k samples > Writing 32-bit complex floats > Output filename: noise.dat > > > > 2013/4/28 Alex Zhang <cingular.a...@gmail.com> > >> I remember that some DC is manually added into the frequency point which >> can be divided by 5Mhz or 10Mhz? Besides the DC at the your central freq, >> be aware of that if the lo offset setting makes your bandwidth cover these >> frequency point, you still can see the peaks. >> Hope I am not wrong, at least It seems that I observed that thing before. >> >> >> On Fri, Apr 26, 2013 at 1:44 PM, Marcus D. Leech <mle...@ripnet.com>wrote: >> >>> On 04/26/2013 02:27 PM, vegihat vegihat wrote: >>> >>>> if i have understand i need to use the --lo-offset of uhd_rx_cfile >>>> >>>> i have gave various values to --lo-offset and only one value has moved >>>> the DC offset (--lo-offset=1G) and the plotfft gives many small spikes >>>> (maybe this is caused to aliasing, but i am not sure) >>>> >>>> which is the rule (value of --lo-offset) to set the DC offset out of my >>>> band? >>>> >>> What I do is set my LO offset to about half my bandwidth, so in your >>> case: >>> >>> --lo-offset 1.0e6 >>> >>> >>> -- >>> Marcus Leech >>> Principal Investigator >>> Shirleys Bay Radio Astronomy Consortium >>> http://www.sbrac.org >>> >>> >>> >>> ______________________________**_________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org >>> https://lists.gnu.org/mailman/**listinfo/discuss-gnuradio<https://lists.gnu.org/mailman/listinfo/discuss-gnuradio> >>> >> >> >> >> -- >> >> Alex, >> *Dreams can come true – just believe.* >> > > -- Alex, *Dreams can come true – just believe.*
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