[USRP-users] (no subject)

Rob Kossler rkossler at nd.edu
Thu Oct 1 15:45:21 EDT 2015


Michael,
In the for loop you provided below, it appears that all of the time
commands are sent right away - probably prior to the first timed command
ever executing in the FPGA.  Or, do I understand it incorrectly.  Assuming
that is correct, is there a maximum number of timed commands that can be
sent to the FPGA?  What happens if you exceed that amount - does the
set_command_time() function or another function block until there is buffer
space for another command or perhaps just report an error?
Rob

On Thu, Oct 1, 2015 at 3:34 PM, Michael West via USRP-users <
usrp-users at lists.ettus.com> wrote:

> Hi Carlos,
>
> You should be able to accomplish that by using timed commands.  You will
> most likely need a separate thread just for the tuning.  Something like:
>
> while (wait_for_start)
>     boost::this_thread::sleep(boost::posix_time::milliseconds(1);
>
> uhd::time_spec_t t = start_time;    // start_time could be global to
> coordinate with data streams
> for (double freq = 1e6; freq <= 16e6; freq += 50e3)
> {
>     usrp->set_command_time(t);
>     usrp->set_rx_freq(freq);  // or usrp->set_tx_freq(freq)
>     usrp->clear_command_time();
>     t += uhd::time_spec_t(0.00512);
> }
>
> Instead of starting and stopping the data streams (which will interfere
> with the tuning), just zero fill (for TX) or throw away the samples (for
> RX) you don't need.  By using the start times of the streams, the metadata
> in the data packets, and the start time of the tuning, you should be able
> to coordinate the tuning with the data without too much effort.
>
> Hope this helps!
>
> Regards,
> Michael
>
> On Mon, Sep 28, 2015 at 2:25 PM, Carlos Quiroga via USRP-users <
> usrp-users at lists.ettus.com> wrote:
>
>> Hello USRP-users:
>>
>> I am sending some complementary pulses in bpsk modulation  for a radar
>> application.
>> I am trying to change the frequency of modulation in the usrp N200. But
>> this change have to be automatic, with a 50 kHz step each 5.12 ms.
>> The frequency begin in 1Mhz and end in 16 Mhz.
>>
>> How can I do this automatically without any slide bar?
>>
>> I have a basic TX daugtherboard.
>>
>> Any Idea would be great and helpful.
>>
>> Thanks
>>
>> --
>> Carlos F. Quiroga Ruiz
>>
>> _______________________________________________
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>> USRP-users at lists.ettus.com
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
>
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