Multi antenna transmit with RFX2400

JSSSSrSSSSmy_Skelto · March 24, 2009, 9:55am

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 diversity transmission.

Thanks,
Jérémy

JSSSSrSSSSmy_Skelto · March 26, 2009, 12:37pm

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 :

JSSSSrSSSSmy_Skelto · March 26, 2009, 12:38pm