Tom Early | 26 Jun 15:19 2016

questions about syncing to an input bit stream that has a header

You can tell from my questions below that I am very new at this. If 
there is some other approach to my OOT that make more sense, please tell 

I am aware of the gr-dsd OOT, but I want to decode/encode using a method 
that won't violate patents.

I'm working on a OOT that will have various blocks to encode/decode 
using an AMBE3000 device.

For decoding, incoming data will have an overall sync of 64+15 bits 
followed by a 660 bit header and then 20 millisecond voice frames with 
the encoded data (72 bits) and a "slow data" (24 bits). Starting with 
the first voice frame, every 21st frame will have a 24 bit frame sync 
instead of slow data. (It's the DStar protocol, see , and 
it uses GMSK to convert between rf and digital.) The AMBE3000 will 
decode the 9 bytes of voice data in the 12 byte frame into 160 audio 
samples (short ints at 8000 per sec). The final voice frame should not 
have any "slow data" but instead have a 48 bit termination pattern).

My dstar_encode_sb block seems more straightforward: When the flow is 
started, just like a delay block, dstar_encode_sb will insert the 
overall sync and header at the beginning of the transmission, then the 
voice frames will be generated from an audio source. I'm unsure how to 
properly terminate the end. Is there another block function that I can 
override to add a final termination frame to the output stream as the 
flow is shutting down?

My dstar_decode_bs is quite a bit more complicated. I would like my 
(Continue reading)

Gavin Jacobs | 26 Jun 00:23 2016

OOT Block on Windows feasible?

I recently installed GNU Radio 3.7 on my Windows 10 laptop. I have been familiarizing myself by building the example ADSB application in GNU Radio Companion. Learned lots, but now I want to build my own blocks. I have searched and found almost nothing on the topic of writing GRC blocks in a Windows environment. There was some mention (about 2 years ago) on this list of someone who had done a Python block. So, is it feasible? and if so, any tips/tricks/suggestions appreciated. Thanks,

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Pavan Yedavalli | 24 Jun 01:36 2016

make command errors with: gnuradio/io_signature.h: No such file or directory


I just installed pybombs and gnuradio successfully, but when I run make in the correct directory, it says gnuradio/io_signature.h: No such file or directory.

I have a feeling it's because I made my prefix /path/to/prefix as opposed to /usr/local, because I can find the file in ./include/gnuradio/io_signature.h and ./src/gnuradio/gnuradio-runtime/include/gnuradio/io_signature.h, so it just seems like it's not pointing to it correctly. I'm sure it's just a simple command for it to know that everything is in /path/to/prefix.

Alternatively, I could just uninstall pybombs and start over with /usr/local as the correct prefix. I'm not sure whether it's the problem, but just hypothesizing (because this didn't happen in my old installation of pybombs/gnuradio with /usr/local as the prefix, unless I'm forgetting that I did something else).

Thanks for the help.

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avinash kalyanaraman | 23 Jun 23:42 2016

Low transmission rate on tx_ofdm causes underflow

Hi All,

I am doing an OFDM transmission with tx_ofdm.grc and receiving it with rx_ofdm.grc. I am using two USRP N210s for this.

I edited the tx_ofdm to set the transmission rate to generate 96-byted packets every 10ms via : message strobe-> random pdu generator->pdu to tagged stream.

However, now I am seeing an underflow ('U') which I think is because my application isn't sending data fast enough to the USRP. The USRP sampling rate is 512K. 

Could you please let me know how I might be able to fix this?


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Chuck Swiger | 23 Jun 16:01 2016

Using wx-2.8 examples on Ubuntu 16

Looks some of the gnuradio/examples/ are written for wxPython2.8 - to
use them in Ubuntu 16 Xenial the packages are still available but not
published, instead Ubuntu has moved on to python-wxgtk3.0 package. 

They can found here:

and needs all these for dependancies:


dpkg -i install those and then examples/uhd/ will work
again in Ubuntu 16. 
West, Nathan | 22 Jun 19:14 2016

Pending feature freeze for GNU Radio Release v3.7.10

Hi all,

I want to give a heads up that we're actively planning the v3.7.10 release of GNU Radio for a couple of weeks from now. We'll go in to a feature freeze within a few days. If you have work you want in the release please wrap it up and submit PRs or at least let us know about it.

Related, the big merge coming in is a new "packet3" branch that's available from the git remote as well as the Github mirror. This branch has a pretty hefty overhaul of packetized modem work from Tom. If you have vested interests in that please review and test that branch.

That's all for now. Cheers,
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Jeon | 22 Jun 09:13 2016

TypeError of enum type in my OOT module. Just one block not the others.

Dear GNU Radio Users

I am building my own module but having difficulties on dealing with C++ headers and Python SWIG.

I have declared my own enum type (including CMakeLists.txt and swig file) [1] and made a working block with this enum type [2]. This works fine when I test the block.

On the other hand, another block [3] fails to pass test with error [4]. The key of the error is: "TypeError: in method 'encode_PSDU_make', argument 1 of type 'OP_MODE'. It's not a logical error nor an error in general_work(). It is an erroro when creating an instance (I am not sure this terminology is correct).

I am very confused that both [2] and [3] have the almost same structure, but one is OK and another is problematic. Currently, I am bypassing this probleme with a workaround by declaring enum OP_MODE explicitly once again in encode_PSDU.h. But it is not looking good and I need to edit source codes two times whenever change on enum OP_MODE happens.

Since these GIST codes are simplified version for brevity, if you need more information please let me know about it.


[1]: "include/myOOTmodule/utils.h, CMakeLists.txt and swig file"
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Martin Braun | 21 Jun 20:48 2016

[PyBOMBS] Close to 2.1.0 release

All y'all (as they say in the south),

I'll soon be tagging the 2.1.0 PyBOMBS release. We've had an insane
number of changes since the last release (2.0.1) and I'd like to
propagate them to PyPi soon.
I'd appreciate more people giving it a try before I do so!

Copied from the manual, here's how to get the latest version:

$ [sudo] pip install [--upgrade] git+

Appreciate any feedback!

Gregory W. Ratcliff | 21 Jun 18:05 2016
Picon error in ::blocks


I did a quick list search for this, but didn't see anything.

Today I fired up a 64 bit Ubuntu 15.04 vm; let it does its normal updates, then "sourced" the shell script and ran pybombs update....

About an hour later after MUCH success the build failed.
Anyone notice this recently?

[ 12%] Building CXX object gr-blocks/lib/CMakeFiles/gnuradio-blocks.dir/
/home/gratcliff/gnuradio/src/gnuradio/gr-blocks/lib/ In member function ‘virtual int gr::blocks::divide_cc_impl::work(int, gr_vector_const_void_star&, gr_vector_void_star&)’:
/home/gratcliff/gnuradio/src/gnuradio/gr-blocks/lib/ error: ‘volk_32fc_x2_divide_32fc’ was not declared in this scope
 _32fc(optr, numerator, (gr_complex*) input_items[inp], noutput_items * d_vlen);
gr-blocks/lib/CMakeFiles/gnuradio-blocks.dir/build.make:4216: recipe for target 'gr-blocks/lib/CMakeFiles/gnuradio-blocks.dir/' failed
make[2]: *** [gr-blocks/lib/CMakeFiles/gnuradio-blocks.dir/] Error 1
CMakeFiles/Makefile2:1957: recipe for target 'gr-blocks/lib/CMakeFiles/gnuradio-blocks.dir/all' failed
make[1]: *** [gr-blocks/lib/CMakeFiles/gnuradio-blocks.dir/all] Error 2
Makefile:146: recipe for target 'all' failed
make: *** [all] Error 2
PyBombs.Packager.source - ERROR - Build failed. See output above for error messages.
PyBombs.Packager.source - ERROR - Problem occurred while building package gnuradio:
Build failed.
PyBombs.update - ERROR - Error updating package gnuradio. Aborting.

Gregory W. Ratcliff

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Damindra Bandara | 20 Jun 22:38 2016

Error when switching between QPSK and BPSK modulations


I am developing an application which changes between the QPSK and BPSK modulations based on the signal level. My transmitter path is set as follows.

File source --> Packet Encoder --> Constellation modulator --.>  USRP sink. 

Initially, the constellation of the 'Constellation modulator' is set to a QPSK  Constellation Rect. Object. To change the modulation to BPSK I change the Constellation Rect. Object to BPSK. 
Everything works fine for the change from QPSK to BPSK. But when I try to change back to QPSK from BPSK I get the following error.

sched: <block pfb_arb_resampler_ccf (12)> is requesting more input data
  than we can provide.
  ninput_items_required = 13525
  max_possible_items_available = 8191
  If this is a filter, consider reducing the number of taps.

I appreciate if you could help me to solve this problem.

Thank you
Damindra Savithri Bandara,
Ph.D. in Information Technology (Candidate)
George Mason University,
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Martin Braun | 20 Jun 21:54 2016

Re: Question about tagged_stream_block

It'll crash. If you know your packet size a priori, you can tell the
scheduler to only provide multiples of a 1000 samples.


On 06/20/2016 07:17 AM, bob wole wrote:
> Hi,
> My  flowgraph contains a tagged_stream_block, B, and it has a
> length_tag_key, say "pkt_len". Each packet has a length of 1000 samples.
> The upstream block (A-->B) tags first sample with key "pkt_len" and
> value 1000 and then the upstream block tags sample number 901 with key
> "pkt_len" and value 1000 instead of tagging sample number 1001. This
> could happen in case of overflow and I know using receive tags that 100
> samples has been lost. So, samples from 901 to 1900 contains a new
> packet. Will the flowgraph work or will it crash?
> I want to write a block that processes exactly only 1000 samples, one
> packet, in a call to work. And the packets start from a specific time
> for example when the rx_time of the sample is mid of any second. 
> --
> Bob
> _______________________________________________
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