# Making new block with GRC or write python **URL:** \ **Category:** GNU Radio\ **Created:** [April 21, 2014, 10:49am UTC](https://www.ruby-forum.com/t/making-new-block-with-grc-or-write-python/240570 "2014-04-21T10:49:07Z")\ **Posts on this page:** 3\ **Page:** 1
**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:** [April 21, 2014, 10:49am UTC](https://www.ruby-forum.com/t/making-new-block-with-grc-or-write-python/240570/1 "2014-04-21T10:49:07Z")
Dear List, To make my question on [https://www.mail-archive.com/removed\_email\_address@domain.invalid/msg48001.html](https://www.mail-archive.com/removed_email_address@domain.invalid/msg48001.html) more clear, I would like to add more details. I want to implement a bidirectional two-way relaying network using 3 USRPs and GNU Radio. The model is at \*attachment 1. \* \*1st slot: \*Two end nodes (A, B) send information to relay node (R) in different frequencies. Relay node receives both and make a bitwise XOR mapping. _2nd slot:_ Relay node sends the XORed message to end nodes. Each end nodes performs another XOR on this message and its original message to extract information from other end node. For time synchronization, the following protocol using a beacon added in relay node has been proposed: \*Node A, B \*(see in _attachment 2_): - Wait for beacon - Receive beacon - Transmit message - Wait for message from relay - Receive message from relay - Restart \*Node R \*(see in _attachment 3_): - Transmit the beacon - Wait for the two messages to be received, - Check for error - Combine the messages, - Transmit the combined message, - Restart My question is should I make this process by making some new blocks in GRC or writing python script? In addition, how to tell a RX/TX chain to start/stop since these USRPs work in half-duplex mode? ## Thank you so much. Hoang Ngo K. Hoang Faculty of Electronics and Telecommunications - University of Engineering and Technology (UET) - Vietnam National University, Hanoi (VNU) Vice-president of Student Association of UET Alternative email: removed\_email\_address@domain.invalid Mobilephone: +84.163.682.7874 ---
**Author:** ![Hoang\_Ngo\_K](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/97f17d/32.png) [@Hoang\_Ngo\_K](https://www.ruby-forum.com/u/Hoang_Ngo_K)\ **Post date:** [April 25, 2014, 5:53am UTC](https://www.ruby-forum.com/t/making-new-block-with-grc-or-write-python/240570/2 "2014-04-25T05:53:01Z")
On Mon, Apr 21, 2014 at 4:47 AM, Hoang Ngo K. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote: > mapping. > > - Wait for message from relay > My question is should I make this process by making some new blocks in GRC > or writing python script? In addition, how to tell a RX/TX chain to > start/stop since these USRPs work in half-duplex mode? > > Thank you so much. > Hoang Take a look at gr-mac: [https://github.com/jmalsbury/gr-mac](https://github.com/jmalsbury/gr-mac) It’s all done in GRC and would be an appropriate starting point. GRC produces Python code, so you can always take that and work in Python when you get into a place with GRC that you can’t do what you want. Tom ---
**Author:** ![Hoang\_Ngo\_K](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/97f17d/32.png) [@Hoang\_Ngo\_K](https://www.ruby-forum.com/u/Hoang_Ngo_K)\ **Post date:** [April 29, 2014, 8:23am UTC](https://www.ruby-forum.com/t/making-new-block-with-grc-or-write-python/240570/3 "2014-04-29T08:23:54Z")
Thank you Tom, I’ve installed gr-mac and try on running some flow graph. Some blocks there give output as message, but I want to take complex samples. How could I convert from message to complex? I used Message Source for that purpose but this error appears: \*NameError: global name ‘blocks\_message\_soure\_0\_msgg\_in’ is not defined \* Best, Hoang