If you don't need high accuracy just "filter" received samples by rx_time or use "Keep M in N" block where N = (samp_rate * 3 sec) and M = (samp_rate * 1 sec).
2017-05-21 12:24 GMT+03:00 Paul I. <paulneli...@gmail.com>: > You need to use USRP "issue_stream_cmd" method (mode: > STREAM_MODE_NUM_SAMPS_AND_DONE). It's allow to receive burst of data by > USRP timer. > If you work in GRC: > 1) Disable streaming autostart for "UHD source" > 2) Create your own block which will periodically issue stream commands > (yes, you need to pass USRP pointer to it) > a) For stream command set "num_samples" = sample_rate * 1 sec > b) Read the USRP timer value, add some time offset to it and use this > value as timestamp for the first stream command > c) Increment timestamp after every stream command > ... > 3) Profit! > > 2017-05-20 10:09 GMT+03:00 Gilad Beeri (ApolloShield) < > gi...@apolloshield.com>: > >> If you need accuracy, I think the asynchronous nature of your method >> might problematic (will appreciate input from GR devs). >> Maybe try a different approach - write the samples to a memory buffer, >> then read from the buffer the exact # of samples you want to write to a >> file. >> >> On Fri, May 19, 2017 at 5:02 PM Deepak Gautam <dpaak...@gmail.com> wrote: >> >>> Dear luca, >>> >>> I had already tried with controlling flow graph dynamically using >>> start(), stop(), lock(), unlock() function. Here i have the part of code i >>> had used. >>> >>> tb=top_block_cls() >>> count=1 >>> tb.start() >>> while (count<5): >>> time.sleep(1.0) #data is recorded in the file >>> tb.lock() >>> tb.disconnect((tb.uhd_usrp_source_0,0),(tb.blocks_file_sink_0, 0)) >>> #disconnect source and block >>> tb.blocks_file_sink_0= blocks.file_sink(gr.sizeof_gr_complex*1, >>> filename,False) # create new file sink to write >>> tb.connect((tb.uhd_usrp_source_0,0),(tb.blocks_file_sink_0, 0)) >>> #connect source with new file >>> count=count+1 >>> time.sleep(2.0) #wait >>> tb.unlock() >>> tb.stop() >>> >>> >>> This program should write the data for 1 second in the file, wait for 2 >>> second and again write for 1 second to another file and so on for 5 4 >>> times. I expect the total data written in the file to be same. But total >>> number of samples recorded in the files are different. for my sampling rate >>> of 25MSps, it should record 25MS per file, but it is around 22Mega sample >>> with different number of data in different file. So it is difficult to >>> reproduce the accurate signal from received data . My application requires >>> very good phase coherence. So i am wondering whether there is something to >>> do to solve in this method or i have to think of another idea. >>> >>> >>> Best Regards, >>> Deepak >>> >>> >>> >>> On Mon, May 15, 2017 at 9:02 PM Moritz Luca Schmid < >>> luca.moritz.sch...@gmail.com> wrote: >>> >>>> Hey Deepak, >>>> >>>> my first idea is to reconfigure the flowgraph. You could connect and >>>> disconnect your source for the time, you want to write data in your file >>>> sink and the time you don't want to. >>>> >>>> You can find infos about the flowgraphs operations here >>>> <https://gnuradio.org/doc/doxygen/page_operating_fg.html>. >>>> >>>> >>>> Best >>>> >>>> Luca >>>> >>>> >>>> >>>> On 15.05.2017 13:53, Deepak Gautam wrote: >>>> >>>> Currently i am working in the USRP using GNU Radio for my masters work. >>>> In my transmitter side, i send data continuously from file source followed >>>> by UHD Sink at the rate of 25 MSPS. In receiver side, I want to write the >>>> data in every two/three seconds after receiving from receiver USRP. >>>> Meaning, write data for 1 sec (25M samples), then dont write for next 2 >>>> second and again write for 1 sec and so on. Is there any suggestion for >>>> this purpose. I look forward for the resposne >>>> >>>> >>>> Best Regards, >>>> Deepak >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing >>>> listDiscuss-gnuradio@gnu.orghttps://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>>> _______________________________________________ >>> 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 >> >> >
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