# Swig error with add\_item\_tag **URL:** \ **Category:** GNU Radio\ **Created:** [April 9, 2014, 8:36pm UTC](https://www.ruby-forum.com/t/swig-error-with-add-item-tag/240364 "2014-04-09T20:36:15Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\ **Post date:** [April 9, 2014, 8:36pm UTC](https://www.ruby-forum.com/t/swig-error-with-add-item-tag/240364/1 "2014-04-09T20:36:15Z")
Hello, I am working with some code from Jared B. who did some work with gnuradio looking at Tire Pressure Sensor Modules (tpms). See the repo here: [GitHub - jboone/tpms: Tire Pressure Monitoring System decoding tools.](https://github.com/jboone/tpms). I am having a hell of a time getting my setup to run his code. I get the following error: jay@ironfist:~/tpms-master/src$ …/src/extract\_bursts.py ~jay/ping\_903.020m\_0.400m\_20140403\_000000z\_rtlsdr.cfile 19.6 \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* T: -256, 0 handler caught exception: Wrong number or type of arguments for overloaded function ‘block\_gateway\_sptr\_block\_\_add\_item\_tag’. Possible C/C++ prototypes are: gr::block\_gateway::block\_\_add\_item\_tag(unsigned int,gr::tag\_t const &) gr::block\_gateway::block\_\_add\_item\_tag(unsigned int,uint64\_t,pmt::pmt\_t const &,pmt::pmt\_t const &,pmt::pmt\_t const &) Traceback (most recent call last): File “/usr/local/lib/python2.7/dist-packages/gnuradio/gr/gateway.py”, line 55, in eval try: self.\_callback() File “/usr/local/lib/python2.7/dist-packages/gnuradio/gr/gateway.py”, line 144, in \_\_gr\_block\_handle ) for i in self.\_\_out\_indexes], File “/home/jay/tpms-master/src/burst\_detector.py”, line 100, in general\_work self.add\_item\_tag(0, nitems\_written + index\_start - self.block\_size, self.\_burst\_tag\_symbol, gr.pmt.PMT\_T, gr.pmt.PMT\_F) File “/usr/local/lib/python2.7/dist-packages/gnuradio/gr/runtime\_swig.py”, line 5172, in block\_\_add\_item\_tag return \_runtime\_swig.block\_gateway\_sptr\_block\_\_add\_item\_tag(self, \*args) NotImplementedError: Wrong number or type of arguments for overloaded function ‘block\_gateway\_sptr\_block\_\_add\_item\_tag’. Possible C/C++ prototypes are: gr::block\_gateway::block\_\_add\_item\_tag(unsigned int,gr::tag\_t const &) gr::block\_gateway::block\_\_add\_item\_tag(unsigned int,uint64\_t,pmt::pmt\_t const &,pmt::pmt\_t const &,pmt::pmt\_t const &) thread[thread-per-block[1]: \]: caught unrecognized exception ^Cjay@ironfist:~/tpms-master/src$ Jared and I made an adjustment to the add\_item\_tag call in the burst\_detection.py code (to make sure the number of arguments passed is right) but still get the same error. I am not sharp enough in python to see what I am doing wrong, nor do I know if there have been changes made to the swig code that impacts the burst\_detection code. Any help would be appreciated. Thanks, Jay Jay R. Twitter: @jradcliffe02 E-Mail: removed\_email\_address@domain.invalid LinkedIn + Resume: [http://www.linkedin.com/in/jradcliffe02](http://www.linkedin.com/in/jradcliffe02) ---
**Author:** ![jay](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ed8c4c/32.png) [@jay](https://www.ruby-forum.com/u/jay)\ **Post date:** [April 10, 2014, 9:53am UTC](https://www.ruby-forum.com/t/swig-error-with-add-item-tag/240364/2 "2014-04-10T09:53:05Z")
Hey Jay, please make sure to provide GR version number for questions like this, and point us to the exact source file and line number that’s causing the trouble. As for your error: On 04/09/2014 08:34 PM, Jay R. wrote: > ``` > gr::block_gateway::block__add_item_tag(unsigned > > ``` > > int,uint64\_t,pmt::pmt\_t const &,pmt::pmt\_t const &,pmt::pmt\_t const &) Python/SWIG is picky with overloading and types. You could try adding a tag\_t instead: t = gr.tag\_t() t.offset = tag\_sample\_index t.key = self.\_burst\_tag\_symbol etc… self.add\_item\_tag(0, t) That said, your code should work. tag\_sample\_index isn’t a double, by any chance? M ---
**Author:** ![jay](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ed8c4c/32.png) [@jay](https://www.ruby-forum.com/u/jay)\ **Post date:** [April 11, 2014, 12:53am UTC](https://www.ruby-forum.com/t/swig-error-with-add-item-tag/240364/3 "2014-04-11T00:53:04Z")
On Wed, Apr 09, 2014 at 12:34:59PM -0600, Jay R. wrote: > jay@ironfist:~/tpms-master/src$ ../src/extract\_bursts.py > ~jay/ping\_903.020m\_0.400m\_20140403\_000000z\_rtlsdr.cfile > 19.6 \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* > T: -256, 0 > handler caught exception: Wrong number or type of arguments for overloaded > function ‘block\_gateway\_sptr\_block\_\_add\_item\_tag’. Short answer: It’s a bug in TPMS’s extract\_bursts.py. Try this diff: - block\_abs = numpy.abs(block\_spectrum) - block\_abs = numpy.abs(block\_spectrum[2:-1]) Long answer: There are two problems, and the change above is a workaround for both. The first problem is that the burst detection algorithm fails on your particular capture file because the DC offset in your file is high. So instead of detecting six separate bursts within your file, it detects one long burst consisting of the entire file. The change above causes the algorithm to completely ignore narrow signals (narrower than 3/256 of your capture bandwidth) centered at 0 Hz. I’m going to suggest this change to Jared because DC offset is a very common defect in SDR captures. However, it is a trade-off. In cases where a capture file does not suffer from DC offset, this change could cause the algorithm to overlook narrow, well-centered signals. The second problem is that there is a bug that causes a negative number to be passed as an argument that is supposed to be an unsigned integer. I think this only happens when a burst is detected right at the start of the input file, so the above change avoids the problem. It’s just a workaround, not a bug fix. Mike ---
**Author:** ![jay](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ed8c4c/32.png) [@jay](https://www.ruby-forum.com/u/jay)\ **Post date:** [April 11, 2014, 1:06am UTC](https://www.ruby-forum.com/t/swig-error-with-add-item-tag/240364/4 "2014-04-11T01:06:31Z")
Much appreciated. Jared and I caught the negative number last night. It then did exactly what you described, finding one huge burst. I am working with him on some of the fsk demod tools he is working on. As far as your other message: I would love to take your course. I know you are giving it at Black Hat, but I am also teaching a class those four days there. Are there any other times you are giving it? One of the frustrations I am having is there is very little out there on demodulation. You can find lots of stuff on finding signals and identifying them. That part I have a decent grip on. post-demodulation I fail at. Much of it is I know what I need to do, but don’t know how to make the blocks/write the code to do it. How much of your course focuses on the demodulation side of things? My fear is that 80% of the courses are on the parts I am comfortable with. My co-worker (Don Weber) took the course, and he is just as lost as I am on this. Thanks, Jay Jay R. Twitter: @jradcliffe02 E-Mail: removed\_email\_address@domain.invalid LinkedIn + Resume: [http://www.linkedin.com/in/jradcliffe02](http://www.linkedin.com/in/jradcliffe02)