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[time-freq] RefLock II configuration

Luis Cupido cupido at mail.ua.pt
Thu Mar 16 19:33:08 UTC 2006


f_conf sets the lock points, and lock points are multiples of the
values in the table. As you know your frequency you should be abble to determine
which submultiple fits better, just that.
So the lock point is for you to decide if you want and can lock to that specific multiple.

(I agree that with such sintetic information as on the txt file it is not evident to configure
nevertheless the minimum necessary is there. I'll can upgrade them with whatever
makes it more easy to understand, if you have any sugestion just let me know).

Lets present a few examples with random values:

For 101.335 000 = xxx.xx5 000 (or xxx.xx0 000)
one can lock at 5 or 2.5 or 1.25 or 1 KHz all will work

For 106.522 500 = xxx.xx2 500 (or xxx.xx7 500)
only 2.5 and 1.25 KHz can be used.

For 106.522 000 = xxx.xxx 000 only 1KHz can be used

For 105.531 250 = xxx.xx1 250 (or xxx.xx3 750, or xxx.xx6 250, or xxx.xx8 750)
only 1.25Khz can be used.

Note that to better understand the way it locks, imagine that the
reflock only looks at the least significant digits of the frequency.
When set to 5KHz lock point as far as the reflock is concerned,
all of the frequencies 102.330 or 99.880 or 180.665 or 47.495 or 42.22 etc
are equal it will lock them 5KHz digit downwards, other digits don't care.
The same for all other lock points.

Since the lock capture range is the same as the lock point
we should always use the highest value possible so to have the
widest lock range (if the tuning range of the VCXO is very
small this is irrelevant). (Phase noise wise 1KHz is the best).

Hope this helps.

Luis Cupido,

  ----- Original Message ----- 
  From: Owen, Michael 
  To: TAPR time and frequency projects 
  Sent: Thursday, March 16, 2006 6:42 PM
  Subject: RE: [time-freq] RefLock II configuration

  Dear Luis,

  I'm sorry, but when I examine r2_enhpps_30_1.txt, I don't see an explanation of how to determine the value for, say, f_conf.  Could you please explain how "-- f_conf=00 locks to 5KHz multiples (internal divider = 5000)"  is related to 1PPS -> 100 MHz?


    -----Original Message-----
    From: time-freq-bounces at lists.tapr.org [mailto:time-freq-bounces at lists.tapr.org] On Behalf Of Luis Cupido
    Sent: Thursday, March 16, 2006 11:25 AM
    To: time-freq at lists.tapr.org
    Subject: Re: [time-freq] RefLock II configuration

    Hi Michael,

    The file "r2_enhpps_30_1.txt" on the configurations zip folder
    has it all.
    I agree it is in a "very compact style" but in fact should have it all.
    Take a look, and if there are specific questions, let me know
    (do it to the list please) I'll be glad to reply.

    Luis Cupido.

    P.S. note that the N numbers on the PCB have different meaning for
    each "pof" configuration file. Be sure to read the " *.pin " for the description
    of where is what.

    The  " f_conf "  configures the lock point (that is the multiple of ).
    for 100. 000 000 MHz use f_conf= 0,0

      ----- Original Message ----- 
      From: Owen, Michael 
      To: time-freq at lists.tapr.org 
      Sent: Thursday, March 16, 2006 2:54 PM
      Subject: [time-freq] RefLock II configuration

      I went out on a limb to convince my employer to try the RefLock II as a means of locking 1PPS to a 100 MHz OCXO.  Now we have received two kits and it's my responsibility to get them up and running.  In the absence of any written documentation, I need some help.  Although I have read through all the messages in the TAPR time-freq archive, I can't find anything that tells how to select the N divisor jumpers for 1PPS -> 100 MHz.  Also, I don't understand what the f_conf(0,1) jumpers are supposed to do.  Could someone please offer a suggestion? 

      73, W9IP


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