Official bladeRF forum

For context, I am referring to the FAQ: https://www.nuand.com/frequently-asked- ... _reference

I would like to synchronise the receive streams of two bladeRF micro xA9 devices. I have an external 10 MHz reference provided by a GPSDO which is distributed to both devices via the J95 connector and setting both devices to lock the PLL to the external reference. The two devices have a master/slave relationship utilising the trigger signal to synchronise RX streams.

I am also aware that one can output a 38.4MHz reference from the device via J92 CLKOUT to other bladeRF's which leads to my following question:

What is the difference between distributing a common external reference to the J95 ports of multiple devices as opposed to daisy chaining the devices via their J92/J93 ports? Which method of clock distribution provides better frequency stability whilst increasing coherence across both devices?

Best regards,

Donny

The method of providing an external 10 MHz reference via port J95 will provide better frequency stability and synchronization between devices as both devices will lock onto a stable and accurate reference source.Among Us

What about distributing a common 38.4MHz reference to all the bladeRF 2.0 devices and using that as the CLK_IN? Would that be better than distributing a common 10MHz to the REF_IN port for frequency stability, phase coherence, and simultaneous sampling across multiple bladeRFs?

Distributing 38.4MHz is much better than distributing 10MHz. However you must ensure the 38.4MHz has good phase noise performance because the bladeRF 2.0 micro's entire clock tree is derive from CLK_IN (if external clocking is selected). The 10MHz reference PLL is great for having the phase noise performance of the on-board crystal, but having an external reference for frequency stability/tracking. The 10MHz reference is good for just low frequency phase noise performance because the PLL combines the onboard crystal's performance with the external reference. Going the CLK_IN route just copies the full external external clock's performance to the bladeRF.