-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi Xianda,
how should we possibly tell? You expect us to be able to guess what is going wrong with your measurement, in an environment that is unknown to us, using a receiving antenna, modified flowgraph and tx signal that you did not really define. As Martin said, if a detector outputs a 1, it might be a false alarm, also known as bad luck. With stochastic problems, you always have to make a trade off between false alarm rate and type II errors. This is called receiver operating characteristic. With most detectors, you can adjust their parameters to accommodate your false alarm rate/detection rate needs. Greetings, Marcus On 15.07.2014 12:56, xianda wrote: > Oh,I guess that because i receive signal which at the frequency of > 2.45e9.It is like the wifi.May be I receive the wifi signal?Am i > right? Thank you. > > > > > > > > > > At 2014-07-15 05:17:35, "Martin Braun" <martin.br...@ettus.com> > wrote: >> On 07/15/2014 09:39 AM, xianda wrote: >>> Hi Martin: Thank you for your kindly reply. Another question I >>> want to ask. When I use the rx_ofdm,I add a UHD:USRP >>> Source.(Environment: USRP N210)I know when the block Schmidl >>> &Cox OFDM synch. detect the signal,the port "detect" will >>> output 1.And I test it.I use the rx_ofdm when I don't use the >>> tx_ofdm.It means that no signal exist.But I find 1 in the port >>> "detect".Why?When no signal exist,it should output 0.Why I see >>> 1 from it? >> >> ...bad luck? It's not impossible to generate false alarms. What >> did you feed the block? >> >> Martin >> >> >> >>> Thank you so much. Best regards, xd >>> >>> >>> >>> >>> At 2014-07-14 04:37:37, "Martin Braun" <martin.br...@ettus.com> >>> wrote: >>>> On 07/13/2014 01:06 PM, xianda wrote: >> Hi all: >> Have you >>>> ever using >>> the >> gnuradio/gr-digital/examples/ofdm/rx_ofdm.grc?And I >>> change the >> rx_ofdm.py as follows: >> >>> self.connect((self.digital_ofdm_chanest_vcvc_0, 1), >> >>> blocks.file_sink(gr.sizeof_gr_complex * fft_len, >>> 'channel-estimate.dat')) >> And i use the matlab: > >Please >>> read the fine manual: >>>> http://gnuradio.org/doc/doxygen/classgr_1_1digital_1_1ofdm__chanest__vcvc.html#details. >>>>> >>>> The channel estimate is on a tag. > >M > >>>> _______________________________________________ >>>> >Discuss-gnuradio >>> mailing list >Discuss-gnuradio@gnu.org >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradi >>> >>> >> >> >> _______________________________________________ Discuss-gnuradio >> mailing list Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >> _______________________________________________ Discuss-gnuradio >> mailing list Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJTxSMPAAoJEBQ6EdjyzlHtRwEH+gPol6VhuE5BBqyq5GUD7H9P GhTufylcZhwuK5XLbZg1l5ZrcqrcJu8+CZRFmWuK2vIml4JhzVPre5gPSbYeRdFs e+aZ+mT3TN62oXXurvq+YM6mnBdewR2bi8h/DtkC77OkB5SvL6j6rREWSg73flCB /sh2hgHuQkJ8d2sh8ut0L1NF6rlbB3l+unwEgjGeLnDyH3fdFjfUDPlh7OiX318w GmfPasCiSMMmcSqXCIaXcHaaVF/cdip7Yd8LQACMKJvZBT9AvGh5i725z3Drytdl 20B69ymrWD93bEdBjN7WAyAAvDJVbE6nWv1gXuUYfkbnGHwIaGomXfU8PQrPY14= =qRmz -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio