On 04/23/2019 02:51 PM, Fabian Schwartau via USRP-users wrote:
Hi,
well, ...
I am recording small slots (up to 2 seconds) of data at different
frequencies, gain, sample rates, etc. I have written a manager for the
USRP where other classes can ask for a certain slot (frequency, sample
count, sample rate, ...). The manager does not know when someone will
ask for data. So it happens that there is nothing to do. In that case
the manager looses track of the current time and does not know when to
start the next command once someone asks for a new slot. In this case
he gets the current time, adds a few hundred ms to be on the safe side
and continues. Even if I would be able to plan that far ahead, I found
out that the USRP is not able to plan commands that are quite far in
the future (it was like 10 seconds or so). Starnge things happen and I
also loose track of the time.
One more reason is that the USRP is not capable of timed sample rate
switches (was discusses here a few month back) which means that the
manager has to wait until all pending commands are done and the data
is received, then switch the sample rate, get the current time (as the
processing/download of the data in the other thread may take some
time), again add a few hundred ms and continue.
Actually I am currently quite pissed as I run into one bug after
another and cannot continue my actual work. I found like another three
critical bugs, but I cannot reporoduce them in smaller programs and I
do not have the time to debug the full UHD library. So I write one
workaround after another.
Best regards,
Fabian
Also, get_time_now() is controlled by set_command_time(). So, for
example, if you have two threads issuing control commands, and one thread
issues a set_command_time(), and then another thread issues a
get_time_now() while there's a set_command_time() window pending, it will
be controlled by the set_command_time(). The USRP device has zero
concept of threading, per se, so it's up to the application to keep track
of stuff like this.
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