Re: [Discuss-gnuradio] Using "send_now=0" on USRP2

[hanwen]

Hi,

Have you got this issue with USRP2 solved.
We're now couping with the similar issue setting the tx_timestamp for choosing a synchronized transmitting time for 2 usrp2.
We use sync_every_pps(true) for reseting the timestamp counter every 1 second with external PPS input. and set the timestamp to 99999999.
But it doesn't work when interporlation rate lower than 10.

Bests,
Hanwen

2009/4/15 Per Zetterberg <address@hidden>

Dear All,

I am trying to issue 50000 calls to tx_16sc (of 371 samples each i.e.,
one ETH packet per call) to the USRP2. I transmit a simple sinuswave. If
I set "send_now=1" in the metadata it works as expected and I can see
the signal on a spectrum analyzer. If I set send_now=0 I can only
occasionally see the signal pass and then for only very short time. Here
are some more details: I first receive a few frames to get the
time-stamp from the received frames, this timestamp is stored in the
variable last_time_stamp. Then I transmit using the code below (the
interpolation factor is set to 10). Is there anything I have
misunderstood ?

metadata.send_now=0;
metadata.start_of_burst=1;
metadata.end_of_burst=1;

int i1;
for (i1=0;i1<NO_ITER-1;i1++) {

   metadata.timestamp=last_time_stamp+10e6+i1*NO_SAMPLES*10;

   if (!u2->tx_16sc(0,
       buffer,
       NO_SAMPLES,
       &metadata)) {
        printf("Transmit data failed!\n");
           };
          metadata.start_of_burst=1;
    };

   metadata.end_of_burst=1;
   u2->tx_16sc(0,
                buffer,
                NO_SAMPLES,
               &metadata);

};


BR/
Per



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