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<gnuradio/fft/fft.h> and <gnuradio/digital/ofdm_cyclic_prefixer.h>.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
>>>>>>
>>>>>>
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