On Thu, Jun 17, 2010 at 06:03:46PM +0800, lishan_wh wrote: > I wonder how can I get the dBm value by using usrp_spectrum_sense.py. > > should I do it as follows? > > fft = gr.fft_vcc() > > c2mag = gr.complex_to_mag_squared() (or without squared?) > > log = gr.nlog10_ff() > > stats = gr.bin_statistics_f() > > self.connect(self.u,s2v,fft,c2mag,log,stats) > > in main function, I defined > > m = parse_msg(tb.msgq.delete_head()) > > Is mean(m.data) the dBm value? If it isn't, how can I get the it?
Hi lishan_wh, the Rx chain (before your flow graph) consists of a lot of analog stuff (including amplifiers) and then your signal is converted to nothing but numbers during the A/D conversion. So, if you mag-square the incoming signal, you get some kind of power, but differing from the absolute power by an unknown factor. You need to calibrate your whole system before you can do actual power measurements. Cheers MB -- Karlsruhe Institute of Technology (KIT) Communications Engineering Lab (CEL) Dipl.-Ing. Martin Braun Research Associate Kaiserstraße 12 Building 05.01 76131 Karlsruhe Phone: +49 721 608-3790 Fax: +49 721 608-6071 www.cel.kit.edu KIT -- University of the State of Baden-Württemberg and National Laboratory of the Helmholtz Association
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