Re: [Discuss-gnuradio] call the work() method

[Marcus Müller]

GRC. You get 1 USRP sink, but it will have 2 independent inputs.
On 31.05.2014 15:22, xianda wrote:
> Hi
>      Thank you so much for your patient instructions.
>      Yes ,I know the "UHD:USRP Sink" can specifies two USRP addresses.But the 
> symbol i try to transmit to the usrp is different.
> They may be should in two flow graph.
> [file source 1] --> [ (I)FFT ] --> [ cyclic prefixer ] --> [ USRP sink 1]
> [file source 2] --> [ (I)FFT ] --> [ cyclic prefixer ] --> [ USRP sink 2]
> Can i realize it in grc?Or should i write the c++ code?
> Thank you.Thank you.
> Best regards,
> xianda
>
>
>
>
>
>
>
>
> At 2014-05-31 09:15:03, "Marcus Müller" <address@hidden> wrote:
>> Hi!
>>
>> The gr-uhd USRP sink can represent multiple USRPs at once.
>> If you have a recent GNU Radio version, in gnuradio-companion your "UHD:
>> USRP Sink" block will have a "Documentation" tab.
>> There is an example that specifies two USRP addresses. This will
>> automatically enable you to transmit the contents of both files
>> simultaneously [1].
>> You should start with the gnuradio-companion, which will generate
>> easy-to-read Python code.
>> Usually, you don't need to write your own blocks to interface with USRPs.
>>
>> Greetings,
>> Marcus
>>
>> [1] "Simultaneously" does not mean "coherently"!
>>
>> On 31.05.2014 14:48, xianda wrote:
>>> Hi:
>>>      Thank you so much for your kindly reply.
>>>      Sorry for my poor English.
>>>      The reason why i directly write the c++ code is that I want to use the 
>>> uhd to control my two usrps send simultaneously.
>>>      The aim i want to reach is that read symbol from file and perform ifft 
>>> and insert cp and then transmit.Just like you write:
>>>      [file source 1] --> [ (I)FFT ] --> [ cyclic prefixer ] --> [ USRP sink 
>>> 1]
>>> [file source 2] --> [ (I)FFT ] --> [ cyclic prefixer ] --> [ USRP sink 2]
>>> I can control them simutanously.Use some class like uhd::usrp::multi_usrp.
>>> Which is the best way to realize it?Use the c++ or write python flow 
>>> graph?Thanks.
>>> Thank you so much.
>>> Best regards,
>>> xianda
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> At 2014-05-31 08:25:53, "Marcus Müller" <address@hidden> wrote:
>>>> Hi Xianda,
>>>>
>>>> some of your emails are really hard to read due to your email client
>>>> writing non-standard-compliant HTML mail. Could you disable
>>>> HTML/multimedia mail?
>>>>
>>>>> What I want to do is that  read symbols from file and perform fft and 
>>>>> insert cp and then transmit to the usrp.
>>>> ok, thanks for clarifying that!
>>>>
>>>>> Just as the "fft" and "OFDM Cyclic Prefixer" do!
>>>> Well, the fft block doesn't read from a file, and ofdm cyclic prefixer 
>>>> does not transmit, but I get your point.
>>>>
>>>>> The easy way is use the <gnuradio/fft/fft.h> and 
>>>>> <gnuradio/digital/ofdm_cyclic_prefixer.h>;
>>>> No!
>>>> In GNU Radio, you build flow graphs out of existing blocks, whenever 
>>>> possible. So you want to use
>>>>
>>>> [file source] --> [ (I)FFT ] --> [ cyclic prefixer ] --> [ USRP sink ]
>>>>
>>>> by instantiating these blocks, and connecting them to a GNU Radio flow 
>>>> graph. Then you let GNU Radio run that flow graph. 
>>>> There's no need to write your own block, so far. Actually, you can do this 
>>>> without writing a single line of code just by constructing
>>>> above flow graph in gnuradio-companion. That will generate the flowgraph  
>>>> setup and starting program in python.
>>>>
>>>> If you need to add more functionality, you usually just add another block 
>>>> to this chain, but from what you've said there will be no need to do this.
>>>>
>>>>
>>>>> But as you said fft_complex_vcc is a block. But now how can i call it in 
>>>>> my code?
>>>> You don't, see my previous post on calling work().
>>>>
>>>>
>>>> Greetings,
>>>> Marcus
>>>>
>>>>
>>>>
>>>> On 31.05.2014 13:53, xianda wrote:
>>>>> Hi:<br/>      Thank you so much.<br/>      What I want to do is that  
>>>>> read symbols from file and perform fft and insert cp and then transmit to 
>>>>> the usrp.Just as the "fft" and "OFDM Cyclic Prefixer" do!<br/>      The 
>>>>> easy way is use the&lt;gnuradio/fft/fft.h&gt; and 
>>>>> &lt;gnuradio/digital/ofdm_cyclic_prefixer.h&gt;.But as you said 
>>>>> fft_complex_vcc is a block.But now how can i call it in my code?(It's a 
>>>>> block.It has work function.)Can i add it's work function in my code?Thank 
>>>>> you.<br/>Best regards,<br/>xianda
>>>>> At 2014-05-31 07:36:24, "Marcus Müller" <address@hidden> wrote:
>>>>>> Hi Xianda,
>>>>>>
>>>>>>> I just want to write c++ code to realize ("fft" block+"OFDM Cyclic
>>>>>> Prefixer").
>>>>>>
>>>>>> Sorry, I still did not understand. I only understand your C++, so here's
>>>>>> my comments:
>>>>>>
>>>>>> The code you posted has really nothing to do with gr::block;
>>>>>> gr::fft:fft_complex is *not* a gr::block, and has no work()!
>>>>>> http://gnuradio.org/doc/doxygen/classgr_1_1fft_1_1fft__complex.html
>>>>>>
>>>>>> Also, I don't see the need to #include
>>>>>> <gnuradio/digital/ofdm_cyclic_prefixer.h>. Is this a mistake or was it
>>>>>> intentional?
>>>>>>
>>>>>> fft_complex really just a convenience wrapper around FFTW.
>>>>>> I haven't tried to test your code, and you could read() directly into
>>>>>> the get_inbuf() buffer, and write directly from your get_outbuf()
>>>>>> buffer, but it looks ok.
>>>>>>
>>>>>> Again: gr::fft:fft_complex is not a block! it is used from within
>>>>>> fft_complex_vcc (which is a block).
>>>>>> All it does is use the FFTW library to perform FFTs, you can do that
>>>>>> yourself without using GNU Radio at all. Only use it when you are
>>>>>> developing a GNU Radio program!
>>>>>>
>>>>>> Greetings,
>>>>>> Marcus
>>>>>>
>>>>>>
>>>>>> On 31.05.2014 13:21, xianda wrote:
>>>>>>> Hi:
>>>>>>> Thank you so much.
>>>>>>> I just want to write c++ code to realize ("fft" block+"OFDM Cyclic 
>>>>>>> Prefixer").
>>>>>>> And I attached my code which just realize ifft but the "OFDM Cyclic 
>>>>>>> Prefixer" has it's work function.
>>>>>>> #include <fstream>
>>>>>>> #include <vector>
>>>>>>> #include <gnuradio/gr_complex.h>
>>>>>>> #include <gnuradio/fft/fft.h>
>>>>>>> #include <gnuradio/digital/ofdm_cyclic_prefixer.h>
>>>>>>>
>>>>>>> std::vector<std::complex<float> *> buff1(64);//read data
>>>>>>> std::vector<std::complex<float> *> buff2(64);//write data
>>>>>>>
>>>>>>> std::ifstream infile("a.dat",std::ifstream::binary);
>>>>>>> std::ofstream outfile("b.dat",std::ofstream::binary);
>>>>>>>
>>>>>>> int main(){
>>>>>>> while(not infile.eof())
>>>>>>> {
>>>>>>> infile.read((char*)&buff1.front(),buff1.size()*sizeof(std::complex<float>));
>>>>>>>
>>>>>>> gr::fft::fft_complex *buff=new gr::fft::fft_complex(64,0);
>>>>>>> gr_complex *bu=buff->get_inbuf();
>>>>>>> memcpy(bu,&buff1.front(),buff1.size()*sizeof(std::complex<float>));
>>>>>>> buff->execute();
>>>>>>> gr_complex *out=buff->get_outbuf();
>>>>>>> memcpy(&buff2.front(),out,buff2.size()*sizeof(std::complex<float>));
>>>>>>>
>>>>>>> outfile.write((char*)&buff2.front(),buff2.size()*sizeof(std::complex<float>));
>>>>>>> }
>>>>>>>
>>>>>>> infile.close();
>>>>>>> outfile.close();
>>>>>>> }
>>>>>>>
>>>>>>> Thank you.
>>>>>>> Best regards,
>>>>>>> xianda
>>>>>>>
>>>>>>> At 2014-05-31 06:33:35, "Martin Braun" <address@hidden> wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 31 May 2014 11:57, "Marcus Müller" <address@hidden> wrote:
>>>>>>>> Hi Xianda,
>>>>>>>>
>>>>>>>>
>>>>>>>>>          I know every block should have it's work or general_work 
>>>>>>>>> function.And i know it's used by scheduler
>>>>>>> For the record, a block that only uses message passing doesn't need a 
>>>>>>> work function - not that that's what you're looking for here.
>>>>>>>
>>>>>>>
>>>>>>> M
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Discuss-gnuradio mailing list
>>>>>>> address@hidden
>>>>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>>>>>> _______________________________________________
>>>>>> Discuss-gnuradio mailing list
>>>>>> address@hidden
>>>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio