Hi, everyone.I am doing the estimation angle of arrival by using USRPs. The problem I want to fix is the initial phase offset of each dboards.From now on, I have searched some knowledge about this issue. But I can not implement the concept. Those concept I got are below: 1. Some kinds of dboard's initial phase offset can remain constant after re-tune by timed command (code). 2. I saw some AOA finding hardware set using another usrp or dboard to transmit a reference signal into the USRPs which are connected to antenna array elements. My simple hardware set is below: Two usrp 2932 (with SBX) One trimble GPSDO to provide 1PPS and 10MHz I use GNUradio 3.7.5.1 , UHD_003.008.002-0-unknown But every time I retune, the initial phase offset is not the same. I use file sink block and print it in matlab. I really do not know where and how to add those 'timed commands' which taught in the USRP Hardware Driver and USRP Manual. In another test, I use one USRP-2932 (SBX) to receive two signals. But I find it is impossible, am I right?? cos the SBX can not use two port(TX/RX & RX2) in the same time. However, I saw some people transmit a reference signal to the receiving USRPs which is connected to antenna array. How to do that kind of calibration?? Can anybody provide or teach me the code of phase calibration by using another USRP? I saw some presentation but there is no source code I can learn... Any example could provide to me or anyone can help me?? (I think I　know those concepts and knowledge but I can implement it in hardware and software) thx a lot !!

Hi, When timed commands are used, the phase offset will be consistent for a each frequency, but each frequency may have a different phase offset. Because external factors (i.e. cables, amplifiers, etc..) can affect the phase offset, calibration of the phase offset(s) must be done at the system level and is left up to the user to do. Adding timed commands to achieve a consistent phase offset is fairly simple. Just add something like this: uhd.timespec_t cmd_time = self.uhd_usrp_source0.get_time_now() + uhd.time_spec_t(0.1) self.uhd_usrp_source0.set_command_time(cmd_time) // Do tuning here self.uhd_usrp_source0.clear_command_time() Regards, Michael On Tue, Nov 3, 2015 at 8:36 AM, 廖鎮瑋 via USRP-users < usrp-users@lists.ettus.com> wrote: > Hi, everyone.I am doing the estimation angle of arrival by using USRPs. > > > > The problem I want to fix is the initial phase offset of each dboards.From now on, I have searched some knowledge about this issue. But I can not implement the concept. > > > > Those concept I got are below: > > 1. Some kinds of dboard's initial phase offset can remain constant after re-tune by timed command (code). > > 2. I saw some AOA finding hardware set using another usrp or dboard to transmit a reference signal into the USRPs which are connected to antenna array elements. > > > My simple hardware set is below: > > Two usrp 2932 (with SBX) > > One trimble GPSDO to provide 1PPS and 10MHz > > I use GNUradio 3.7.5.1 , UHD_003.008.002-0-unknown > > But every time I retune, the initial phase offset is not the same. I use file sink block and print it in matlab. > > I really do not know where and how to add those 'timed commands' which taught in the USRP Hardware Driver and USRP Manual. > > In another test, I use one USRP-2932 (SBX) to receive two signals. > > But I find it is impossible, am I right?? cos the SBX can not use two port(TX/RX & RX2) in the same time. > > However, I saw some people transmit a reference signal to the receiving USRPs which is connected to antenna array. > > How to do that kind of calibration?? > > Can anybody provide or teach me the code of phase calibration by using another USRP? > I saw some presentation but there is no source code I can learn... > > Any example could provide to me or anyone can help me?? > > (I think I　know those concepts and knowledge but I can implement it in hardware and software) > > thx a lot !! > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >