# Problem with TCP Source and TCP Sink Block

**URL:** <https://www.ruby-forum.com/t/problem-with-tcp-source-and-tcp-sink-block/242569>\
**Category:** GNU Radio\
**Created:** [July 3, 2015, 7:44am UTC](https://www.ruby-forum.com/t/problem-with-tcp-source-and-tcp-sink-block/242569 "2015-07-03T07:44:51Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\
**Post date:** [July 3, 2015, 7:44am UTC](https://www.ruby-forum.com/t/problem-with-tcp-source-and-tcp-sink-block/242569/1 "2015-07-03T07:44:51Z")

</div>

Hi

I am using GNU Radio 3.6.4.2 on Ubuntu 12.04. I am unable to use the TCP  
Source and Sink blocks which I want to connect to hardware. Whenever I  
use them, I get the following error:

File “/home/vlab/Documents/top\_block.py”, line 13, in   
from grc\_gnuradio import blks2 as grc\_blks2  
File  
“/usr/local/lib/python2.7/dist-packages/grc\_gnuradio/blks2/ **init**.py”,  
line 22, in   
from packet import options, packet\_encoder, packet\_decoder,   
File  
“/usr/local/lib/python2.7/dist-packages/grc\_gnuradio/blks2/packet.py”,  
line 21, in   
from gnuradio import gr, digital  
ImportError: cannot import name digital

Could you please help me out?

Thanks

Anamay Kane

---

<div class="post-metadata">

**Author:** ![anamay\_k](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c68b51/32.png) [@anamay\_k](https://www.ruby-forum.com/u/anamay_k)\
**Post date:** [July 3, 2015, 6:37pm UTC](https://www.ruby-forum.com/t/problem-with-tcp-source-and-tcp-sink-block/242569/2 "2015-07-03T18:37:21Z")

</div>

Hi Anamay Kane,

that seems to be an installation issue.

Generally. GNU Radio 3.6.4.2 is outdated. If you need the 3.6 API, use  
the latest version from the 3.6 branch, which is 3.6.5.1. But that is  
not very likely to see updates/bugfixes in the future.

If you can, try to use GNU Radio 3.7. If you don’t have to work with  
very complex existing GNU Radio modules that need GNU Radio 3.6, now  
would be a good time to switch to 3.7.

The problem you’re seeing is unrelated to the TCP sink/source. It’s just  
that python says the gnuradio module doesn’t have a “digital” submodule.  
Did you build this flow graph yourself or did you get if from somewhere  
else?

Best regards,  
Marcus

PS: By the way: though Ubuntu 12.04LTS is still supported by GNU Radio,  
it’s really old – maybe you’d want to switch to at least GNU Radio  
14.04LTS by now.

---

<div class="post-metadata">

**Author:** ![anamay\_k](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c68b51/32.png) [@anamay\_k](https://www.ruby-forum.com/u/anamay_k)\
**Post date:** [July 3, 2015, 8:08pm UTC](https://www.ruby-forum.com/t/problem-with-tcp-source-and-tcp-sink-block/242569/3 "2015-07-03T20:08:29Z")

</div>

Hi Marcus,

is it possible to remove GNURadio from 12.04 with apt-get and install  
the GNURadio 3.7 branch with pybombs without switching to Ubuntu 14 ? I  
dont know if the dependencies are ok for 3.7 in 12.04.

regards,  
Andy

Am 03.07.2015 um 18:36 schrieb Marcus M.:

---

<div class="post-metadata">

**Author:** ![anamay\_k](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c68b51/32.png) [@anamay\_k](https://www.ruby-forum.com/u/anamay_k)\
**Post date:** [July 3, 2015, 8:12pm UTC](https://www.ruby-forum.com/t/problem-with-tcp-source-and-tcp-sink-block/242569/4 "2015-07-03T20:12:35Z")

</div>

I haven’t tested that myself, but I’ve been told pybombs does target  
Ubuntu 12.04. It will install a hell of a lot of manually built  
dependencies into your prefix (which would be available for installation  
from package repositories on “modern” Ubuntus), but it should work.  
3.7 is the default for pybombs, by the way.

Best regards,  
Marcus