------------------------original mail----------------------------------
Message: 11
Date: Fri, 13 Apr 2012 08:25:36 -0700
From: Josh B.[email protected]
To:[email protected]
Subject: Re: [Discuss-gnuradio] Question about USRP2 Tx procedure
Message-ID:[email protected]
Content-Type: text/plain; charset=ISO-8859-1
On 04/13/2012 06:54 AM, Pan, Luyuan wrote:
continue;time to build the flow graph. But we do an experiment to get the time we
and it send the cached data at a precise-controlled time, but I can not
persuade myself.
Can anyone interpret the strange phenomenon? Any suggestion is
appreciated, thank you!!
The is buffering in the USRP2, about 1 MB. Give your sample rate and 4
bytes per sample you can approximate the sleep time.
The more proper way to do this is to send an end-of-burst tag with the
last sample and to wait on the async message queue for a burst ACK
packet.
About the TX tags for the sink block:
http://gnuradio.org/cgit/gnuradio.git/tree/gr-uhd/include/gr_uhd_usrp_sink.h#n52
Also see the async message source:
http://gnuradio.org/cgit/gnuradio.git/tree/gr-uhd/include/gr_uhd_amsg_source.h
-josh
Hello,
In order to find out the reasons, today we did another test, we
used wireshark to capture the data through the wEthernet card. But, we
guess the problem may lies in the FIFO in the software side, the
scenarios are:
- we use while (time.time() - t1< 0.05) and no time.sleep(), then the
receive side can get only one packet. the useful data through the
Ethernet is about 55 packets(not take into account the packet less than
1498 bytes, we consider them as the control info). - we use while (time.time() - t1< 0.05) and time.sleep(0.65), so we
can receive all the data(10 packets). And the data through the Ethernet
is nearly 600 packets. For the fact 1/10 almost equals 55/600, we think
USRP2 send the data out immediately after he get it from the host PC.
The main problem now is for some unknown reason the PC did not pass the
data to USRP2, so he has nothing to send.
Did I misunderstand something or some other reasons? Thank you for your
help!
–
Best regards,
Pan, Luyuan