Hi The way it’s normally found is in a control loop. The fact that the loop is “dead” for 50 or 500 steps and then suddenly does something is what you quickly notice. If you are manually tuning a loop, it does show up.
Bob > On May 7, 2016, at 7:26 AM, Azelio Boriani <[email protected]> wrote: > > How can anyone of us tell wheater a tuning step is or not at the level > of 10 at -15? Maybe only TVB can... > Are you sure that the 50 times greater than is not related to your > measure instead of the real capability of the 5680A? > > On Sat, May 7, 2016 at 6:51 AM, Nick Sayer via time-nuts > <[email protected]> wrote: >> I got a second 5680 in the mail the other day and so far my firmware isn’t >> bricking it, so.. yay. >> >> A couple of odd things have turned up, though. >> >> 1. So far as I can experimentally tell, the tuning step on this unit is 50 >> times larger than the 17E-15 quoted by FEI. Either the tuning curve is not >> linear or the tuning range is not what they claim (or both). I’d like to get >> a feel for whether the standard deviation of the mid-range (near zero) >> tuning step is. Is it closer to what I’m observing or FEI’s spec? The answer >> will instruct me on how to pick the PLL gain constant for the firmware. >> >> 2. Directly clocking an AVR from the 5680A is unreliable prior to lock. I >> haven’t exhaustively examined the startup behavior of the 5680, but power-up >> reset of my GPS board used to not happen a lot of the time, and manual reset >> was required. The AVR datasheet says that as long as the clock frequency is >> kept within 2% from cycle to cycle that that’s ok, but either this 5680A >> isn’t doing that or the AVR datasheet is wrong. Fortunately, there’s a >> software workaround: fuse the controller for the internal 8 MHz oscillator >> and switch over (I was surprised to learn that changing system clock sources >> on the fly is an option) to the 5680 only once a physics lock is indicated >> by the lock pin. That seems to be acceptably reliable. My purpose in >> mentioning it is to see if anyone has examined the pre-lock behavior of the >> 5680 (I understand it’s not a particularly interesting question) to see >> exactly how jumpy it really is before it locks. >> >> _______________________________________________ >> 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. > _______________________________________________ > 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. _______________________________________________ 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.
