Hi Richard / Marcus, I have a C/C++ implementation of async message to file (file_message_sink) as well. It takes messages which are PMT dictionaries and writes only specific key values. So you would make an SNR key and then tell the file message source to write that key. You can use comma-delimited keys to write many keys at once. The output format is .csv so it should be easy to parse. I haven’t merged it for the latest GNURadio code, but it was working as of August 2015.
https://github.com/garverp/gnuradio/tree/msg_file_sink <https://github.com/garverp/gnuradio/tree/msg_file_sink> Hope this helps. PWG > > From: Marcus Müller <[email protected] > <mailto:[email protected]>> > Subject: Re: [Discuss-gnuradio] Async Message to File > Date: February 19, 2016 at 1:04:42 AM MST > To: Richard Bell <[email protected] <mailto:[email protected]>> > Cc: GNURadio Discussion List <[email protected] > <mailto:[email protected]>> > > > Have a look at the python struct docs [1]; I think the problem is indeed that > you write 64bit floats, and read 32bit floats; so "f" instead of "d" I think > :) > Sorry to keep you busy this long :) > > [1] https://docs.python.org/2/library/struct.html > <https://docs.python.org/2/library/struct.html> > > On 19.02.2016 00:57, Richard Bell wrote: >> Sorry, still not working. Values seem to be either 0 or gigantic. I think >> it's because the single 64 bit value is being written as 8 consecutive bytes >> as you said, and I'm not handling that anywhere once I read the file into >> octave. I'll try and figure it out next time I'm working on this. >> >> Thanks, >> Rich >> >> On Thu, Feb 18, 2016 at 3:12 PM, Marcus Müller <[email protected] >> <mailto:[email protected]>> wrote: >> Argh, sorry, to_float returns a float64, which of course means that Python's >> file.write is a bit confused by this request, and it's getting late :/ >> concentration used to be better. >> >> So, add >> import struct >> where the other imports are. >> >> Then, >> self._file.write(struct.pack("d", pmt.to_float(msg) ) ) >> should >> 1. get the 64 bit float from the pmt message, >> 2. pack that into a string object according to the format "d" (which simply >> says, take a single double and give it to me as raw 8 bytes) >> 3. writes that to the file. >> >> Best regards, >> Marcus >> >> >> On 19.02.2016 00:05, Richard Bell wrote: >>> Sorry Marcus, I'm not familiar with pmts and message passing things to >>> handle these errors on my own. When I change >>> "self._file.write(pmt.serialize_str(msg))" to >>> "self._file.write(pmt.to_float(msg))", I get the following error in grc >>> terminal >>> >>> handler caught exception: expected a character buffer object >>> Traceback (most recent call last): >>> File "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/gateway.py", >>> line 73, in eval >>> try: self._callback(arg) >>> File "/usr/local/lib/python2.7/dist-packages/msgtools/msg_file_sink.py", >>> line 41, in _msg_handler >>> self._file.write(pmt.to_float(msg)) >>> TypeError: expected a character buffer object >>> thread[thread-per-block[101]: <block msg_file_sink (47)>]: caught >>> unrecognized exception >>> >>> Thanks for the help. >>> >>> Rich >>> >>> On Thu, Feb 18, 2016 at 2:55 PM, Marcus Müller < >>> <mailto:[email protected]>[email protected] >>> <mailto:[email protected]>> wrote: >>> Ah, sorry, no, the block just takes the raw serialized pmt and writes it to >>> a file [1]: >>> >>> self._file.write(pmt.serialize_str(msg)) >>> >>> You could use python with pmt module to unserialize, but: >>> >>> if you just replace "serialize_str" with "to_float", this should give you >>> what you expect. Notice this is really just experimental; copy the block to >>> your own code. I'll probably rewrite as something in C++ to make it useful >>> on platforms without python, too. >>> >>> Cheers, >>> Marcus >>> >>> [1] >>> https://github.com/marcusmueller/gr-msgtools/blob/master/python/msg_file_sink.py#L41 >>> >>> <https://github.com/marcusmueller/gr-msgtools/blob/master/python/msg_file_sink.py#L41> >>> >>> >>> On 18.02.2016 23:13, Richard Bell wrote: >>>> I just tested it. I expect to see log scale values of SNR coming out of >>>> the estimator block. When I look at this directly using a function_probe >>>> and qt_gui_label in grc, I see proper estimates. When I load the file >>>> produced by the msg_file_snk into octave, I see incorrect values ranging >>>> from e-40 to e+40. I assumed the msg_file_snk stored values as float, so I >>>> used the read_float_binary.m script >>>> on the file to plot. Are we having a type conversion issue here? >>>> >>>> Rich >>>> >>>> On Thu, Feb 18, 2016 at 1:33 PM, Marcus Müller < >>>> <mailto:[email protected]>[email protected] >>>> <mailto:[email protected]>> wrote: >>>> Sorry, I forgot to git push; could you git pull? >>>> >>>> On 02/18/2016 10:27 PM, Richard Bell wrote: >>>>> There is only one block in your git, Variable To Message, and no built in >>>>> Message File Sink in GR. I'm using gr 3.7.10. How did you see this being >>>>> used? >>>>> >>>>> Rich >>>>> >>>>> On Thu, Feb 18, 2016 at 1:12 PM, Richard Bell < >>>>> <mailto:[email protected]>[email protected] >>>>> <mailto:[email protected]>> wrote: >>>>> Excellent thanks. >>>>> >>>>> Rich >>>>> >>>>> On Thu, Feb 18, 2016 at 1:09 PM, Marcus Müller < >>>>> <mailto:[email protected]>[email protected] >>>>> <mailto:[email protected]>> wrote: >>>>> Sorry, took a while longer, juggling multiple mails: >>>>> >>>>> <https://github.com/marcusmueller/gr-msgtools>https://github.com/marcusmueller/gr-msgtools >>>>> <https://github.com/marcusmueller/gr-msgtools> >>>>> >>>>> use the msg_file_sink :) >>>>> >>>>> >>>>> On 02/18/2016 09:35 PM, Marcus Müller wrote: >>>>>> From the top of my head, there's nothing that does that... yet. >>>>>> Let's see if I can hack together something in python that does that. >>>>>> Gimme a second. >>>>>> >>>>>> On 02/18/2016 09:22 PM, Richard Bell wrote: >>>>>>> I want to store the output SNR measurement messages of the MPSK SNR >>>>>>> Estimator Probe >>>>>>> to a file, but I'm not sure how to transform async messages to a stream >>>>>>> to get them into a file. Would someone please recommend a method of >>>>>>> doing this in GRC. >>>>>>> >>>>>>> Rich >>>>>>> >>>>>>> >>>>>>> _______________________________________________ >>>>>>> Discuss-gnuradio mailing list >>>>>>> [email protected] <mailto:[email protected]> >>>>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>>>>> <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio> >>>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> Discuss-gnuradio mailing list >>>>> <mailto:[email protected]>[email protected] >>>>> <mailto:[email protected]> >>>>> >>>>> <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio>https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>>> <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio> >>>>> >>>>> >>>>> >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> [email protected] <mailto:[email protected]> >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> <https://lists.gnu.org/mailman/listinfo/discuss-gnuradio> >>>> >>>> >>> >>> >> >> > > > > > >
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