Hi all, I'm currently trying to find out how much USRPs B210 are capable of doing in different tasks.
One of these tasks is transmission of burst with use of UHD's burst api. To access it I have implemented a GNU Radio app that uses tx_time and packet_len tags. Particularly the application was configured to send bursts containing complex sinusoid (frequency 1kHz) every 2.5ms. Length of the burst is 2ms, so there should be 0.5us of gap between bursts. The result of recording of this signal is shown on the attached picture and it is not what is expected: the gap is about 800us and the length of pulse is about 1.7ms. About 300us of signal is not transmitted at all. What it means is that it is problematic to send bursts with use of burst api. I can attach 300us of signal at the beginning of a burst but what if there are two bursts in a row that are closer than 300us? One of my aims is to add ability to transmit gsm bursts to gr-gsm. GSM bursts are spaced by 8.25us of guard periods... Probably I could find some other workaround with use of hacks that probably will fail in specific situations and the whole simplicity provided by burst api will go away anyway. But I would prefer to not do that if it's possible. I checked on USRP X310 and everything is fine there - it starts to transmit almost immediately. Why does it take so long (and loss of 0.3ms of signal at the beginning) for USRP B210 to start transmit anything? Do you know how to make it start transmit faster (100x faster definitely would make burst api in B210 much more usable). (UHD used for the test was 3.9.2, carrier frequency of the signal was 940MHz) -- Best Regards, Piotr Krysik
_______________________________________________ USRP-users mailing list USRP-users@lists.ettus.com http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
