[time-nuts] GPS lock of the FE5680. Current experiment and question
lists at rtty.us
Fri Feb 10 23:52:49 UTC 2012
I think you will need some sort of analog detector to get what you are looking for.
On Feb 10, 2012, at 6:34 PM, Chris Albertson <albertson.chris at gmail.com> wrote:
> On Fri, Feb 10, 2012 at 2:53 PM, paul swed <paulswedb at 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
> 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 at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts