UHD has always been a very generic device API—necessarily so due to the large variety of hardware types in the USRP “line up”.
Having said that there’s nothing that prevents you from diving into the code on both the software and FPGA side to create and expose whatever you want. Sent from my iPhone > On Jan 3, 2021, at 1:23 PM, Ofer Saferman via USRP-users > <usrp-users@lists.ettus.com> wrote: > > > Hello Marcus, > > Thank you for your reply. > > Is there support today in software for direct register writes to the AD9361 > device for the E310? > If there is, I think I can use SYNC and a modified firmware to implement > Multi-chip synchronization. > > Regards, > Ofer Saferman > >> On Sun, Jan 3, 2021 at 7:00 PM <usrp-users-requ...@lists.ettus.com> wrote: >> ---------- Forwarded message ---------- >> From: "Marcus D. Leech" <patchvonbr...@gmail.com> >> To: usrp-users@lists.ettus.com >> Cc: >> Bcc: >> Date: Sat, 02 Jan 2021 15:18:06 -0500 >> Subject: Re: [USRP-users] Hacking E310 units for synchronization >> On 01/02/2021 02:44 AM, Ofer Saferman via USRP-users wrote: >> > Hello, >> > >> > I must say that I am a bit frustrated. >> > When I purchased multiple E310 units it was with the hope I will be >> > able to synchronize them mainly based on: >> > https://kb.ettus.com/Synchronization_and_MIMO_Capability_with_USRP_Devices, >> > >> > it shows the E310 as MIMO capable and having a reference clock input. >> > Of course, now I know that not to be true. At least the reference >> > clock part. It seems that the MIMO part might be incorrect as well. >> > >> > If I hack the clock and patch an external clock connector to be used >> > instead of the internal TCXO will I be able, using existing UHD >> > software and firmware, to synchronize multiple E310 units? >> > >> > I will be able to provide a common clock to multiple units and I will >> > be able to provide a 1-PPS signal through the SYNC pins of multiple >> > units that is generated from the same common clock. >> > I need these E310 to transmit and have their base-band samples >> > perfectly time aligned. >> > >> > How is multi-chip synchronization of the AD9361 devices being done by >> > UHD? By using the SYNC pin and setting >> > usrp->set_time_source("external")? Is it enough? Do I need to handle >> > it on my own? How? >> > >> > I figured the internal TCXO frequency of E310 is 40 MHz. Can I provide >> > an external clock of different frequency? Maybe 10 MHz? Or does it >> > require a major change in software or firmware? >> > >> > Does anybody have a different idea how to get E310 units synchronized >> > at sample level without voiding the warranty and hacking an external >> > clock? >> > >> > Please help. >> > >> > Regards, >> > Ofer Saferman >> > >> > >> The E310 was never designed for multi-unit MIMO, although it does 2x2 >> MIMO just fine, and there are plenty of folks using it for that, >> including stacks for various wireless protocols. The AD9361 >> inherently supports 2x2 MIMO due to the shared LO architecture between >> the two TX and two RX channels. >> >> The AD9361 SYNC_IN pin does get tied to the Zynq FPGA, but the UHD >> code-base doesn't use it. I'll note that for most telecom-type >> MIMO implementations, zero-phase-offset is NOT a requirement, just >> ongoing phase coherence. >> >> Similarly the B2xx series does 2x2 MIMO just fine, but it was never >> designed for multi-unit MIMO, although due to the clocking architecture, >> the B2xx could likely (no guarantees) be made to do a multi-unit MIMO >> implementation. >> >> The SYNC input connector on the E310 is designed to: >> >> (A) Provide a higher longer-term quality than the on-board clock. >> (B) Allow for TDM synchronization on system deployments where that is >> important. >> >> Due to the high residual phase-noise of the DPLL implementation on the >> SYNC input on the E310, it cannot be used to produce a working >> multi-unit MIMO (or any other kind of phase-coherent) application. > > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, 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
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