Re: [Discuss-gnuradio] Multi antenna transmit with RFX2400

[Jérémy Skelton]

Hi, again

I should have precise that I'm mainly interested in some piece of  
advise.

In fact, I found the test_mimo_tx.cc in the trunk but it is designed  
for usrp2 and I'm not sure about how I can reuse from it.

I also had from other people the following code allowing me to  
transmit on both antennas but I don't know what is transmitted on each  
antenna as I don't clearly understand where is the separation between  
the sides A and B.
How can I say for example which symbol goes on side A and how are side  
A and B synchronised when sending different symbol on each ?

int main(int argc,char **argv)
{
 unsigned int i1;
 unsigned int InterpRate;
 unsigned int nchannels, DdcFreq, LOFreq, gain;
 unsigned long RF_freq;
        usrp_standard_rx_sptr rx0, rx1;
        usrp_standard_tx_sptr tx0, tx1;

 db_flexrf_mimo db_aside0,db_bside0;
 db_flexrf_mimo db_aside1,db_bside1;
 struct sched_param sp;

 number_of_buffers_wanted=atoi(argv[1]);
 if (number_of_buffers_wanted>MAX_NUMBER_OF_BUFFERS)
   number_of_buffers_wanted=MAX_NUMBER_OF_BUFFERS;
 if (number_of_buffers_wanted<2)
   number_of_buffers_wanted=2;

 RF_freq=atof(argv[2]);
 gain=atoi(argv[3]);

 InterpRate=16;

 rx0 = usrp_standard_rx::make(0, InterpRate);
 tx0 = usrp_standard_tx::make(0,InterpRate*2,2,47768); //0xBA98 	0b  
1011 1010 1001 1000

 if (1) {

   unsigned int counter=0;
   bool underrun;

   if(gruel::enable_realtime_scheduling()!=gruel::RT_OK){
     printf("Problems enabeling realtime scheduling!!!\n");
   }

   db_aside0=db_flexrf_mimo(rx0,tx0,0);
   db_bside0=db_flexrf_mimo(rx0,tx0,1);

   db_aside0.configure_tx(0);
   db_aside0.tune_tx(RF_freq,0);
   db_bside0.configure_tx(0);
   db_bside0.tune_tx(RF_freq,0);

   db_aside0.set_tx_auto_tr(true);
   db_bside0.set_tx_auto_tr(true);

   tx0->set_nchannels(2);

   ifstream l("data_to_usrp.dat", ios::binary);
   int i1;
   for (i1=0;i1<number_of_buffers_wanted;i1++)
     l.read((char *) CollectedData[i1],NUMBYTES);

   l.close();

   short* p;

   p=(short *) &CollectedData[0][0];
   for (i1=0;i1<10;i1++) {
       cout << "Buffer=" << *p  << "\n";
       p++;
   };

   tx0->start();

   while (1) {
     tx0->write((void *) CollectedData[counter++%  
number_of_buffers_wanted],
                              NUMBYTES,&underrun);
     if (underrun)
       cout << "Underrrun \n";
   };
 };

Le 24-mars-09 à 09:54, Jérémy Skelton a écrit :

> Hi,
>
> I was wondering how I can transmit synchronously on two antenna  
> using two RFX2400 on the same USRP1 motherboard.
> It should be possible as the daugtherboards are MIMO capable but  
> does anyone have some c++ working piece of code ?
>
> My goal is to implement an Alamouti scheme for diversity transmission.
>
> Thanks,
> Jérémy
>
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