Hi, For your application, please experiment with the following command:
./usrp_spectrum_sense.py -A TX/RX --fft-size=25 --samp-rate=25e6 --gain=15 --dwell-delay=0.25 --tune-delay=0.25 --channel-bandwidth=8e6 470e6 800e6 Note that 'freq_step' should remain unchanged at '0.75 * usrp_rate' in the script to make sure signals at the edge of the incoming front-end signal bandwidth (25MHz) are not missed. Mike -- Mike Jameson M0MIK BSc Email: m...@scanoo.com Web: http://scanoo.com On 7 April 2013 17:22, Jincheng Zhang <perfume0...@gmail.com> wrote: > Thanks Mike. I'm a little confused. The parameters are listed as follows: > > sample-rate: > channel-bandwidth: > freq_step: > fft_size: > > You mean that I should set sample-rate be 25e6, channel-bandwidth be 8e6, > freq_step be 8e6 and fft_size be 25? > > If we set the fft-size be 25, then which 8 bins I should select to > calculate the power? By the way, since the magnitude of FFT bin is decimal, > maybe I should change the magnitude of FFT bin values to mw and add the 8 > bins, and then transfer to decimal again? Since we cannot straightly add > the FFT bin values in decimal. > > By the way, how about the "self.connect", should I add the log parameter > to it? > > Thanks. Hope for your reply. > > > > On Mon, Apr 8, 2013 at 12:11 AM, Mike Jameson <m...@scanoo.com> wrote: > >> Hi Jincheng, >> >> Try setting the UHD sample rate to 25e6 and the number of fft bins to 25 >> which will give you 1e6 Hz per bin. Adding up the magnitude of 8 bins >> (1MHz * 8 = 8MHz) will therefore give you the wanted channel power in >> decimal format (magnitude). >> >> In case you are confused, I recently updated usrp_spectrum_sense.py to >> include a --channel-bandwidth setting which rounds up the frequency >> displayed to the nearest frequency. I'm working on making it cleaner by >> adjusting the fft size to match the wanted channel. In the meantime, set >> '--channel-bandwidth=8e6' to make the frequency round to the nearest 8MHz >> frequency. >> >> Hope that helps, >> >> Mike >> >> -- >> Mike Jameson M0MIK BSc >> Email: m...@scanoo.com >> Web: http://scanoo.com >> >> >> On 7 April 2013 16:23, Jincheng Zhang <perfume0...@gmail.com> wrote: >> >>> I want to use usrp_spectrum_sense.py to sweep the Hong Kong TV band >>> which ranges from 470MHz to 806MHz and get every channel's power in dB. >>> Each channel's frequency band is 8MHz. >>> >>> Now I'm using USRP2 with TVRX2 daughter board. I have installed the >>> latest gnuraio and uhd. But when I use the usrp_spectrum_sense.py to get >>> the power of each channel, some FFT bin values are extremely big. In >>> particular, I'm not sure abou the self.connect(self.u, s2v, fft, c2mag, >>> stats). It doesn't take "log" as the parameter, >>> >>> FFT size is 2048, sample-rate is 12.5MHz(to let the decimation be 8M), >>> freq_step is 8MHz. Anyone has any ideas about how to use >>> usrp_spectrum_sense.py to calculate each channel's power? >>> >>> >>> On Sun, Apr 7, 2013 at 8:24 PM, Jincheng Zhang <perfume0...@gmail.com>wrote: >>> >>>> Hi, all, >>>> >>>> I use the usrp_spectrum_sense.py to sweep the TV band from 470MHz to >>>> 806MHz. But when I use self.connect(self.u, s2v, fft, c2mag, log, stats), >>>> the FFT bin values I got are all zero. >>>> Also, what's the magnitude of FFT bin value? Thanks. >>>> >>>> -- >>>> Best regards, >>>> Jincheng Zhang >>>> >>> >>> >>> >>> -- >>> Best regards, >>> Jincheng Zhang >>> Department of Information Engineering >>> The Chinese University of Hong Kong >>> http://personal.ie.cuhk.edu.hk/~zj012/ <http://www.jxqc.org/> >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >>> >> > > > -- > Best regards, > Jincheng Zhang > Department of Information Engineering > The Chinese University of Hong Kong > http://personal.ie.cuhk.edu.hk/~zj012/ <http://www.jxqc.org/> >
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