"QAM Demod" error in GRC

GNU Radio
1

Hi all,

I’m using GRC and the simple flow graph(1) at receiver is as follows:

Usrp source---->qam demod---->file sink

It works fine at first. However, when I tried to execute another similar
flow graph(2) that was built before UPDATING GNURADIO from 3.5.0 to
3.6.0.
an error occurs:

Generating:"/home/azalea/exp/top_block.py"

executing:"/home/azalea/exp/top_block.py"

File :"/home/azalea/exp/top_block.py", line 79

Self.digital_qam_demod_0=----------->

Syntax error: invalid syntax

(I looked up the python file, line 79 and line 80 are:

Self.digital_qam_demod_0=----------->

Cannot find ‘gray_coded’: digital.qam.qam_demod(

)

Then, I return to the mentioned flow graph(1), same error again.

I also tried to start a new flow graph or make/make install gnuradio,
but in
vain.

I’m just confused. The flow graph(1) worked well even after updating
gnuradio. After that and before the error I didn’t remove or modify any
module in gnuradio.

Thanks a lot!

Best,

Jia

2

This is a bug.
In file gr-digital/grc/digital_qa_demod.xml the line
gray_coded = $gray_coded
should be changed to
mod_code = $mod_code

3

jiajue ou wrote in post #1064430:

Hi all,

I’m using GRC and the simple flow graph(1) at receiver is as follows:

Usrp source---->qam demod---->file sink

It works fine at first. However, when I tried to execute another similar
flow graph(2) that was built before UPDATING GNURADIO from 3.5.0 to
3.6.0.
an error occurs:

Generating:"/home/azalea/exp/top_block.py"

executing:"/home/azalea/exp/top_block.py"

File :"/home/azalea/exp/top_block.py", line 79

Self.digital_qam_demod_0=----------->

Syntax error: invalid syntax

(I looked up the python file, line 79 and line 80 are:

Self.digital_qam_demod_0=----------->

Cannot find ‘gray_coded’: digital.qam.qam_demod(

)

Then, I return to the mentioned flow graph(1), same error again.

I also tried to start a new flow graph or make/make install gnuradio,
but in
vain.

I’m just confused. The flow graph(1) worked well even after updating
gnuradio. After that and before the error I didn’t remove or modify any
module in gnuradio.

Thanks a lot!

Best,

Jia

I solved by editing the file
/usr/local/share/gnuradio/grc/block/digital_qam_demod.xml

and by changing of the line

mod_code

to

gray_coded

I used that for 3.6.1 version

Joeldo