2010/12/5 lishan_wh <lishan...@126.com>: > Hi, all > I want to plot a figure with the samples from usrp, but I have some > questions. Here is the flowgraph: > usrp.source_c --> gr.streams_to_vector(gr.sizeof_gr_complex*1, 1) --> > gr.complex_to_mag(1) > --> gr.message_sink(gr.sizeof_float*1, self.msg_sink_msgq_out, True)
Why are you using streams_to_vector that way? It looks like you're creating vectors with a single element in it. > Here, self.msg_sink_msgq_out = gr.msg_queue(2) > In main function, I did this: > msg = tb.msg_sink_msgq_out.delete_head() > a = int(msg.arg1()) > b = int(msg.arg2()) > s = msg.to_string() > float_data = numpy.fromstring(s, numpy.float32) > for bin in float_data: > print bin > Questions are sa follows: > (1) Is my code correct? If it isn't, how should I modify it? > (2) What is the return value of gr.msg_queue(2)? I mean what's the meaning > of "a","b","s" in this code? > (3) Is what stored in "s" the amplitude of the samples? If I plot the figure > with s, can I get the envelop of the signal? (4) How to calculate the time > interval between each sample? Can I set the collecting time for USRP? For > example, I want to collect the signal for 1 second. > Thank you! Any help will be appreciated! Why are you using a message sink? If you want to plot, why not use either the WX or QT plotting tools? Use the gnuradio-companion and drop down a graphical sink. If you just want to run some data through the graph and plot it afterwards, store it to a vector or a file_sink and then plot it later. Tom _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio