You're right. The whole point of the TwinRX boards is to give you coherent channels, and you can build a coherent 4-channel *receiver*.
However, TwinRX can't transmit, so for 4×4 MIMO, you'll need something else. Since there's no dual-transmit-channel daughterboards, you'll need to coordinate the phases of four different TX-capable daughterboards. Therefore, you'll need a clock distributor like the octoclock. Haven't tried it in a while, but the clk and pps out of the X3x0 series should solve that issue, however: you could link two USRP X3x0 that are equipped with e.g. two UBX-160 each through that to get 4 coherent TX channels, and use a single USRP X3x0 with two TwinRX as receiver with 4 coherent RX channels. Best regards, Marcus On 27.02.21 15:50, Ali G. Dezfuli via USRP-users wrote: > Hi all, > When USRP X3x0 is used with TwinRX daughterboards, we can have up to 4 rx > channels. > (ref:AN-244, Direction Finding with the USRP™ X-Series and TwinRX™) > But in AN-881 (Selecting a USRP Device) in Table 4, it says that USRP X3x0 > needs > OctoClock for 4x4 MIMO !!! > I wonder when X3x0 can receive 4 channels with TwinRX, why it can NOT be used > in 4x4 > MIMO w/o OctoClock. > > regards, > AGD > > _______________________________________________ > USRP-users mailing list > [email protected] > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com _______________________________________________ USRP-users mailing list [email protected] http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
