How to start signal receiving simultaneously on a large number of LimeSDR-USB boards

Projects LimeSDR
1

I need to start signal receiving simultaneously on a large number of LimeSDR-USB boards. Receiving should start exactly simultaneously: +/- 1 sample. That is, each board should start receiving a signal with its two channels synchronously with other boards.

It seems that there is no standard way to do this. I found some ideas on the forum (Synchronize two LimeSDR), but I did not understand how exactly to solve my problem. For example, BladeRF boards have a trigger through which a pulse is sent to start receiving.

Tell me how to start signal receiving simultaneously on a large number of LimeSDR-USB boards to get a coherent receiving?

2

Indeed in that post you can see how to manually synchronize two or more boards, but I doubt it can be precise up to 1 sample. From what I remember it’ll be precise up to 1360 samples in mono channel or 680 in dual channel. This is because the FPGA packs samples into packets of 1360 samples, and sets a single timestamp for that packet. So when you compare timestamps between boards, you can have up to 1360 or 680 samples of difference.