Hi usrp-users, I recently started working on a *multilateration* based localization scheme to detect a tag USRP (reader). The 100MHz OFDM packets (STF +LTF + information bits) are* transmitted at 100 MSps to the reader* via the anchor hub USRP X310. I am new to handling the time_spec and other features available to control transmission. I have to transmit a really huge packet (*>130000 samples ~ 1.3 to 3 ms*) so that the streaming and reception appears to be continuous for a good duration of time frame for accurate reader detection.
Few Questions: Q1 ; What is the maximum buffer size I can set for transmission. Is it 33445667 samples? I found it on the user manual? Q2 : Is the read buffer on the receive streamer any different form the transmit buffer in terms of maximum size it can receive before it goes into overflow , API control etc? Q3 : I assume ,* I cannot stream a 100 MSps data directly using a 1G ethernet car*d without potential underflow. So I used tim_spec feature to transmit after a fixed duration. Within this time the API should be able to fill the buffer at a slower rate (33MSps if that is the max capability), and allow smooth transmission without underflow. I am receive some packets at the reader , but they seem to be truncated, or abruptly starting or ending. pseudo code to control transmission at 100MSps using 1G: metadata.start_of_burst = true; metadata.end_of_burst = false; while(not stop_signal_called){ metadata.has_time_spec = false; metadata.end_of_burst = false; *g_usrp->set_time_now(uhd::time_spec_t(0.0)); g_time_spec = g_usrp->get_time_now() + uhd::time_spec_t(0.04);* metadata.time_spec =g_time_spec; tx_streamer->send(&buff[0], buff.size(), metadata); metadata.has_time_spec = false; metadata.start_of_burst = false; metadata.end_of_burst = true; tx_streamer->send("", 0, metadata); * boost::this_thread::sleep(boost::posix_time::milliseconds(50));* } Please do help. It is really a critical part of my research project. I am limited to using a 1G Ethernet card, and I need to find a work around to the 100MSps transmission issues. Thanks Karan Suri MS. Electrical and Computers University Of Michigan- Ann Arbor
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