On 04/02/2018 08:05 PM, Martin Braun via USRP-users wrote:
On 03/16/2018 11:49 AM, Reinhold Frederick William Hollender via
USRP-users wrote:
I just wanted to share my experience getting two Rx streams at different
rates working with the B210 in case someone else tries to do the same
thing in the future.
The only other resource I found on this
(http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/2015-April/041655.html)
seemed to have conflicting information, and no real resolution.
I also didn't see anything like this described in the knowledge base,
although perhaps I was looking in the wrong place :)
Following some breadcrumbs in the UHD source, I was able to get the
attached sample to work reliably.
The important points:
-> There's no need to have multiple 'multi_usrp' objects because
device.make() will return the same object if it's already setup anyway
-> Both streams need to be read in the same thread (there were comments
that hinted at this in recv_packet_demuxer_3000)
-> The streams need to be kept in sync by keeping the number of sample
read by each stream the same ratio as the sample rates (otherwise one
stream will get behind and the other will overflow).
William,
thanks for pointing this out! You might want to add that the rates need
to be integer multiples of each other, or the FPGA can't handle the
resampling.
-- M
Hah! I didn't know the B2xx FPGA would do that.
I guess the multi_usrp synchronizer does not "balk" because the first
packets on each stream will have the same time-stamp, and unless there
are overflows,
it'll never care again.
+1 would nod in admiration again....
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