Hi,[posted to S.E.D in the hope that a hardware analog might exist]
I synchronize the "clocks" on physically distributed processors such that two or more different machines can have a very finely defined sense of "synchronized time" between themselves.
During development, I would measure this time skew (among other factors) by locating these devices side-by-side on a workbench interconnected by "unquantified" cable. Then, measuring the time difference between to "pulse outputs" that I artificially generate on each board.
So, I could introduce a disturbance to the system and watch to see how quickly -- and accurately -- the "clocks" (think FLL and PLL) come back into sync.
How do I practically do this when the devices are *deployed* and physically distant (vs. "electrically distant" as in my test case)?
Two ideas come to mind:1) two equal length cables to connect the "pulse outputs" from their respective originating devices to the test gear. 2) two *radios* to do the same thing -- after accounting for different flight times [Though I wonder how hard it is to qualify two different radios to have the same delay, etc. Far easier to trim two long lengths of wire to the same length!]
Of course, I would like to minimize the recurring cost of any solution as it is just present for system qualification (and troubleshooting) and offers no run-time advantage to the design.