Hi Ofer, I don't really know the answer but you might want to search past posts on the topic of E310 gps synchronization. Some of the posts are fairly old (~2016, 2017), but they indicate timing accuracies that are on the order of several microseconds. Perhaps this is related to the E310 having a GPS but not a GPSDO as indicated in the users manual. If this level of accuracy is not acceptable for your application, you may need to consider alternatives. Rob
On Sat, Dec 5, 2020 at 12:04 PM Ofer Saferman <o...@navigicom.com> wrote: > Hello Rob, > > Thanks for the response. > I am not trying to get the LOs to sync in phase. I know that is not > possible unless I use a common external LO. I have a method to find and > cancel the phase difference of caused by the LOs. > I am only trying to get the base-band Tx samples to be synced. > I was wondering whether the 1-PPS signal synchronizes the 10 MHz > references of all E310 in frequency or in phase. > > Regarding your other question - I plan to run the software on each of the > E310 independently without any host computer. Thus, if the clocks of the > units can be synced I can set the transmission to start 1 minute in the > future (or something similar) and I am hoping since the clocks are truly > synced to get synced base-band Tx samples on different E310 units. > > Regards, > Ofer Saferman > > On Fri, Dec 4, 2020 at 10:46 PM Rob Kossler <rkoss...@nd.edu> wrote: > >> Hi Ofer, >> Here is my understanding >> - The E310 can sync to a PPS signal (either external input or obtained >> from GPS). From this PPS, the E310 derives the 10MHz ref signal and uses >> that as ref for LO signal. So, there will be lots of phase variation >> between the LOs in all of your E310 devices even though they will all be >> trying to stay in sync with a 1 pulse-per-second signal. >> - Regarding your time synchronization question, there are examples of >> setting the E310 clock (using set_time_next_pps, I think) to match the GPS >> clock. Thus, all of your E310s could have the same time. But, how do you >> plan to control all of your E310s when you want the transmit to turn on? >> Will you have an SSH session to each of them? >> Rob >> >> On Fri, Dec 4, 2020 at 2:28 PM Ofer Saferman via USRP-users < >> usrp-users@lists.ettus.com> wrote: >> >>> Hello, >>> I would like to synchronize several E310 devices. >>> It is my understanding that the only way to do that is by connecting a >>> GPS antenna and performing disciplining to a derived 1-PPS signal. >>> I have a few questions to help me better understand how to make it work: >>> 1. Does GPS disciplining achieve frequency lock between devices or phase >>> lock? >>> 2. How to start transmitting at the exact moment on all synchronized >>> devices? Can the unit clock be synchronized to GPS clock? and then just >>> start the transmission with some delay from unit clock on all devices? Can >>> someone share the relevant C commands to perform the time synchronization >>> to GPS clock or point to a relevant code example? >>> >>> Thanks, >>> Ofer Saferman >>> >>> >>> -- >>> This message has been scanned for viruses and >>> dangerous content by *MailScanner* <http://www.mailscanner.info/>, and >>> is >>> believed to be clean. _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >> > -- > This message has been scanned for viruses and > dangerous content by *MailScanner* <http://www.mailscanner.info/>, and is > believed to be clean.
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