Thanks. I didn't expect the actual input to shift with the LO offset.
----------------------------- Jacob Knoles On Fri, Aug 25, 2017 at 9:08 AM, <mle...@ripnet.com> wrote: > That's probably because you set your bandwidth to be somewhat narrow, so > with offset tuning, you were only seeing the deeply-filtered data. > > > > > > > On 2017-08-25 11:23, Jacob Knoles wrote: > > I found my issue. When I set my center frequency to monitor I also > provided a LO offset. The intention is to not have the LO included in the > response. > > For some reason it seams this pulled the receive frequency with it. By > removing the LO offset I am getting the data I expect to see. > > At this time I am not sure why this is happening? > > ----------------------------- > Jacob Knoles > > > On Fri, Aug 25, 2017 at 8:12 AM, Jacob Knoles <knole...@gmail.com> wrote: > >> The numbers coming out are essentially zero. Looking at the chart it >> reads -1.3e-17. There are a lot of values that do come out exactly zero, as >> they become -inf (or something like -370) after going through the log10 >> mathematics. >> >> The signal I am inputting however is a simulated BT signal with the peak >> at -40 dBm and modulated. At the one frequency I am monitoring it results >> in a square wave. So I expect to see a distinct change in the output >> numbers. >> >> ----------------------------- >> Jacob Knoles >> >> >> On Thu, Aug 24, 2017 at 6:15 PM, Marcus D. Leech via USRP-users < >> usrp-users@lists.ettus.com> wrote: >> >>> On 08/24/2017 08:11 PM, Jacob Knoles via USRP-users wrote: >>> >>> Hello, >>> >>> I am trying to do a simple receive function that grabs data for 12 >>> seconds, calculates the log10 power and then plots power vs time. >>> >>> I am using the GnuRadio C++ API and have done a prototype using GnuRadio >>> Companion. I am also feeding in a dummy signal using a vector signal >>> generator. >>> >>> While running the Companion code I get exactly the results I expect to >>> get, as seen in this image: >>> >>> [image: Inline image 1] >>> >>> The top time plot is displaying each step of the calculation chain, Red >>> is the real part of the complex number, green is the imaginary part and >>> blue is the magnitude. >>> >>> The lower plot shows the power vs time trace that I am after for this >>> test, the calculation being used is 20*Log10(mag) - 17. >>> >>> The offset was calculated by comparing a known signal on a spectrum >>> analyzer. >>> >>> So now my issue. When I take this prototype and implement it in C++ >>> (that is what my program is using) I do not get any results back at all. >>> >>> Here is the C++ resulting plot of the real complex values only: >>> >>> [image: Inline image 2] >>> >>> As can be seen all the values are essentially zero. >>> >>> Here is the code snippet that is handling the capture, it returns a >>> std::vector<float> which is plotted elsewhere in the software. (I have >>> confirmed that the plotting software is not the issue.) >>> >>> _rate = 5e6; >>> //---------------------------------------------------------- >>> ---------------------- >>> //-- Make a top block >>> //---------------------------------------------------------- >>> ---------------------- >>> auto tb = gr::make_top_block( "TraceCapture" ); >>> >>> //---------------------------------------------------------- >>> ---------------------- >>> //-- make the usrp >>> //---------------------------------------------------------- >>> ---------------------- >>> auto stream_args = uhd::stream_args_t( "fc32", "sc16" ); >>> stream_args.channels.push_back( 0 ); >>> auto usrp_source = gr::uhd::usrp_source::make( >>> uhd::device_addr_t( "" ), stream_args ); >>> usrp_source->set_samp_rate( _rate ); >>> usrp_source->set_center_freq( uhd::tune_request_t(carrier_freq, >>> 10e6) ); >>> usrp_source->set_gain( _gain_one ); >>> usrp_source->set_bandwidth( 1e6 ); >>> usrp_source->set_antenna( "RX2" ); >>> >>> //---------------------------------------------------------- >>> ---------------------- >>> //-- Make the necessary flowgraph blocks >>> //---------------------------------------------------------- >>> --------------------- >>> auto complex_to_mag_sptr = gr::blocks::complex_to_mag::make( ); >>> //auto nlog10_sptr = gr::blocks::nlog10_ff::make( 20, 1, -17.4 ); >>> auto vector_sink_sptr = gr::blocks::vector_sink_f::make( ); >>> auto complex_to_real_sptr = gr::blocks::complex_to_real::make( >>> ); >>> >>> //---------------------------------------------------------- >>> ---------------------- >>> //-- Connect the flowgraph >>> //---------------------------------------------------------- >>> ---------------------- >>> //tb->connect( complex_to_mag_sptr, 0, nlog10_sptr, 0 ); >>> //tb->connect( nlog10_sptr, 0, vector_sink_sptr, 0 ); >>> //tb->connect( complex_to_mag_sptr, 0, vector_sink_sptr, 0 ); >>> tb->connect( complex_to_real_sptr, 0, vector_sink_sptr, 0 ); >>> tb->connect( usrp_source, 0, complex_to_real_sptr, 0 ); >>> >>> tb->start( ); >>> std::this_thread::sleep_for( std::chrono::milliseconds( >>> static_cast<long long>( capture_time * 1000 ) ) ); >>> >>> tb->stop( ); >>> tb->wait( ); >>> >>> return std::make_shared<std::vector<float>>( >>> vector_sink_sptr->data( ) ); >>> >>> >>> When I run the code on my B210 I get no errors, the RX2 led lights as >>> expected, all the numbers get calculated as expected yet no matter what I >>> have tried I am getting only zeros from the B210 >>> >>> Additionally I am working on Windows 10 with VS 2015. I have installed a >>> binary version of GnuRadio. Here is the flowgraph in grc for reference as >>> well. >>> >>> [image: Inline image 1] >>> >>> Any help will be greatly appreciated!! >>> >>> Thanks >>> >>> ----------------------------- >>> Jacob Knoles >>> >>> >>> _______________________________________________ >>> USRP-users mailing >>> listUSRP-users@lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >>> Do you mean "essentially zero" or actually zero? There's a difference. >>> >>> >>> >>> _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >>>
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