Re: Problem migrating an OOT module that uses FFT from 3.8 to 3.9

2022-01-30 Thread Ralf Gorholt

Hello Ron,

thank you very much.

I have walked right into the trap a second time :-( I should attach a
Post-It to my monitor screen to remind me that I might need to adapt the
CMakeLists.txt files when I change something...

Long story short, it works now :-)

Regards,

Ralf

Am 29.01.2022 um 23:54 schrieb Ron Economos:

Ralf,

Yes, I  was thinking about how I had done things in my 3.8 OOT's where
I had used this syntax instead:

fft::fft_complex *ofdm_fft;

and

ofdm_fft = new fft::fft_complex(ofdm_fft_size, false, 1);

The other thing to check is the linking. Like so.

https://github.com/drmpeg/gr-paint/blob/master/CMakeLists.txt#L78

and

https://github.com/drmpeg/gr-paint/blob/master/lib/CMakeLists.txt#L25

Ron

On 1/29/22 14:24, Ralf Gorholt wrote:

Hello Ron,

d_fft_calculator is (and was in the 3.8 version) an object and not a
pointer. That's why I already use the . and not the ->

Regards,

Ralf

Am 29.01.2022 um 21:35 schrieb Ron Economos:

Ralf,

I'm not sure if you've done this already, but when you use
d_fft_calculator, you need to change from -> to . to access it.

Ron

On 1/29/22 12:24, Ralf Gorholt wrote:

Hello all,

I am currently trying to migrate an OOT module that uses an FFT object
internally from  GNU Radio version 3.8 to 3.9.

In my .h file I have got this:

    //old: gr::fft::fft_complex d_fft_calculator;
    gr::fft::fft_complex_fwd d_fft_calculator;

and in the constructor member initializer list this:

  //old: d_fft_calculator(gr::fft::fft_complex(pow(2.0, 10 +
mode),
true, 1)),
  d_fft_calculator(pow(2.0, 10 + mode), 1),

The module compiles without a problem but when I start the flowgraph I
get the message "ImportError:
/usr/local/lib/libgnuradio-dl5eu.so.1.0.0:
undefined symbol: _ZN2gr3fft3fftISt7complexIfELb1EED1Ev". It looks
to me
that somewhere "fft_complex" is still called behind the scenes but I
can't see where.

Can anyone tell me how I need to correct this?

FYI, I have recreated the module and the blocks with gr_modtool and
then
copied the relevant code from the old to the new version.

Thank you very much and kind regards,

Ralf










DVB-T transmit question

2022-01-30 Thread Szilassi Andras
Hello,

I am currently working on a dvb-t remodulator for our passive radar at my
university.
With the available example IQ file, I was able to get the receiving example
program running, but I ran into some problems with the transmit example.

When I run a .ts mpeg stream through the example, for some reason in the
place where the cyclic prefix should appear, the output is constant zero.
The reason I think that something is wrong with the prefixing is that the
output signal is periodic in the time domain ( for around ~ 200 us there is
no signal, then for ~ 800 us there is and so on). The CP length is set at
1/4 so that confirms that.

I dont have enough in-depth knowledge yet to find the answer in the source
files, so if anyone could help me I would really appreciate it.

Thanks is advance,
András
Technical University of Budapest


Re: DVB-T transmit question

2022-01-30 Thread Ron Economos
Seems fine here. Can you try the unmodified example flow graph? The 
example Transport Stream can be downloaded here:


https://www.w6rz.net/adv8dvbt23qam64.ts

Also, which version of GNU Radio are you using?

Ron

On 1/30/22 08:40, Szilassi Andras wrote:

Hello,

I am currently working on a dvb-t remodulator for our passive radar at 
my university.
With the available example IQ file, I was able to get the receiving 
example program running, but I ran into some problems with the 
transmit example.


When I run a .ts mpeg stream through the example, for some reason in 
the place where the cyclic prefix should appear, the output is 
constant zero.
The reason I think that something is wrong with the prefixing is that 
the output signal is periodic in the time domain ( for around ~ 200 us 
there is no signal, then for ~ 800 us there is and so on). The CP 
length is set at 1/4 so that confirms that.


I dont have enough in-depth knowledge yet to find the answer in the 
source files, so if anyone could help me I would really appreciate it.


Thanks is advance,
András
Technical University of Budapest