Something wrong with the block "Pre decoder"

[yefengzhishu]

Hello!There's something wrong with the block "Pre decoder" on my gnuradio.The block "Pre decoder" is just in the list which is on the right of the gnuradio software.But when I drag the block "Predecoder" into the flowgragh window ,the flowgraph window became totally white.What can I do fix this problem?Really looking forward to your help!Thank you very very much!

[skoslowski]

What GR version are you on? Can you open GRC from a console and see what exception is thrown when you drop the block in the GUI?

[yefengzhishu]

I use GRC 3.7.2.
When I drop the block in the console window showed this:

[jdemel]

I can't reproduce the error. But I'm using a newer version of GR. (v3.7.6.1-41-g0bea2cce)

• Can you tell me which grc file was open, when you did this.
• Did you open all the other grc files?

So far my guess is that this bug is related to some GRC display issue. Older v3.7 versions showed this bug because of some combination with message ports and a variable number of streaming ports.

[yefengzhishu]

I guess I found why my "Pre Decoder" bolck was wrong! My partner tried to do the compile process again and this error showed up:

In this picture "错误" means "error".
I met this problem too when I did this step, and at that time I just replace the function "volk_free" and "volk_malloc" with "free" and "malloc".I guess maybe this is the reason why I meet the problem which I proposed at the first time.
So could you help you to solve this compile problem?Thank you very much!

[skoslowski]

My guess is that all these problems go away once you update GNU Radio. We'll change the required version in the readme and manifest.

[yefengzhishu]

When I type in "sudo apt-get install gnuradio" in the terminal window , it says gnuradio has already been the lasted version.But when I check the version of GNURadio ,it is still 3.7.2.1.

[skoslowski]

Looks like 3.7.2.1 is what your OS is shipping. You can install a newer version pretty easy using http://gnuradio.org/pybombs

[yefengzhishu]

The problem was successfully solved after I installed the GNURadio 3.7.5!Thank you very very much!Best wishes to you!

[yefengzhishu]

Sorry to bother you again.Do you know any GNU Radio project about the LTE transmitter?

[jdemel]

gr-lte is a receiver implementation. in python/lte_test is some Python code to generate test data. It is incomplete though. In particular, the part to generate stream samples is missing.

I'd be happy to merge any contributions that would improve this situation. Also a transmitter implementation with GR blocks would be welcome.