Hi I think you will need some sort of analog detector to get what you are looking for.
Bob On Feb 10, 2012, at 6:34 PM, Chris Albertson <albertson.ch...@gmail.com> wrote: > On Fri, Feb 10, 2012 at 2:53 PM, paul swed <paulsw...@gmail.com> wrote: >> Just for fun have built up a simple multi-chip project to try my hand at >> locking the FE5680 using the external efc connection mod. mentioned in >> time-nuts. Typical counter micro rs 232 port stuff. >> >> Essentially the system is 2 X 24 bit counters that toggle back and fourth >> every interval selectable from 1 to 65000 seconds accumulating counts. I am >> measuring the 10 Mhz of the RB and using a novatel superstar II GPS rcvr. I >> do have a better timing rcvr but this was handy and at this point most >> likely good enough. > > Do you ever need such a large counter? As you say the counts are only > small integers. If the two are close they would not overflow even a > 4-bit counter. One way to go is to have only a two bit counter (just > a pair of flop flops) and end the integration as soon as the second > bit flips. If you are building a FLL you only need to know which is > faster. > > If you want faster convergence I think you have to measure relative > phase and use a PLL. Then you don't need to wait for a full cycle. > Maybe only a few degrees of phase difference is enough > > My plan is to use the 74HC4096 is the detector. It has the required > flip flops inside. Use that to dive the RB5680 and then when they are > reasonably close the 74HC4096 also contains an XOR type phase > detector, so switch to that. > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.