> Ie the output of the counter becomes > (more or less) random. Which in turn means the lower 4 bit of the > input to the PI control loop are wrong[1]. Or in terms of time, we > might be off by +/-2^4*42ns=672ns, which is a major hit against the > PI loop (like knocking it with a sledge hammer).
But these numbers don't go directly to the PI loop, there is a software layer between that can inspect for outliers. This is how engineers can reduce costs by knowing when something needs to be perfect and when it does not need to be. In the end the controller works about as good as it needs to. What saves this is the unstably of the cheap 24MHz clock. If the clock problem happens the randomness will make it soon stop happening and the software can just ignore the outliers. You have to look at the whole system and not just the hardware. Much of the functionality is in the software. -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
