[USRP-users] R: X300 STREAM_MODE_NUM_SAMPS_AND_DONE length limitation

Vladimir www2008_2 at mail.ru
Mon Oct 2 13:23:21 EDT 2017


Daniele,

Thank you for your advice! The problem here (not so big though) is that upon receiving of needed number of samps you need to stop streaming and that implies waiting for some timeout while excess samps being flushed (as I understood, after issuing STREAM_MODE_STOP_CONTINUOUS you have to clear input buffers using something like streamer->flush_all(0.01);). I'm trying to estimate how long that timeout should be, and in some cases it obviously would be more or less worse than a possible scenario without timeouting.

Vladimir


>Понедельник,  2 октября 2017, 16:05 +03:00 от Disco Daniele <daniele.disco at telecomitalia.it>:
>
>I have the same problem.
>In the generation of the streamer
>uhd::stream_cmd_t stream_cmd(uhd::stream_cmd_t::STREAM_MODE_START_CONTINUOUS);
>erase the instruction stream_cmd.num_amps = total_num_samps; (or similar)
> 
>and instead to use a counter over the samples use a counter over the blocks of data that the streamer acquires.
> 
>In b210 each acquisition is of 2044 samples
>In E310 is of 1016 (samps_per_buff)
> 
> 
>You can divide the number of samples (>0xfffffff) for samps_per_buff and make a for loop to acquire all the data that you need
>rx_stream->revc(buff_ptrs, samps_per_buff, md, timeout)
> 
>I hope this help you
> 
>Da: USRP-users [mailto:usrp-users-bounces at lists.ettus.com] Per conto di  Vladimir via USRP-users
>Inviato: venerdì 29 settembre 2017 16:53
>A: usrp-users
>Oggetto: [USRP-users] X300 STREAM_MODE_NUM_SAMPS_AND_DONE length limitation
> 
>Hello,
>
>Trying to save more than 2 sec trace with X300 at Fsamp = 100MHz, I encounter some block length limit of 0x0fffffff = 268.4 MSamps, which means only 2.6 sec of time. A bit surprised to see this in 64-bit environment... The assertion is in module rx_vita_core_3000.cpp:
>
>UHD_ASSERT_THROW(stream_cmd.num_samps <= 0x0fffffff);
>
>Is this some physical limit, or it can be patched to a larger value? It's kind of inconvenient to solve this through continuous streaming when you need a trace of a certain length...
>
>Vladimir
>
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