[time-nuts] DPLL for 10MHz

Azelio Boriani azelio.boriani at screen.it
Mon May 7 21:10:49 UTC 2012 

OK, so 1 PPS GPS to Rb -> need a TIC; 10MHz Rb to OCXO -> need a PLL. Are
you interested in an all digital 10nS single shot TIC that gives you a 2's
complement number (negative at the left of the GPS PPS and positive at the
right)? Here it is. This is my TIC, I use it on all my GPSDOs.


LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITY PPSPSI IS
PORT (PPSTIEOut: OUT std_logic_vector (23 downto 0);
PPSInA, PPSInB, Clock100, Clock20: IN std_logic);
END ENTITY PPSPSI;

ARCHITECTURE RippleCounter OF PPSPSI IS
SIGNAL PPSPhaseCntAB, PPSPhaseCntBA: std_logic_vector (22 downto 0);
SIGNAL PPSPhaseLtc: std_logic_vector (23 downto 0);
SIGNAL PPSADlyed, PPSBDlyed: std_logic_vector (4 downto 0);
SIGNAL PPSGateAB, PPSGateBA, PPSLtcA, PPSRstA, PPSLtcB, PPSRstB, StopCntAB,
StopCntBA: std_logic;
SIGNAL RstGateAB, RstGateBA, OvrLtcAB, OvrLtcBA, PPSLtcA1, PPSLtcB1,
PPSA2BSign: std_logic;

BEGIN
PPSAtoBSign: PROCESS --Sign will be 1 when A leads B (that is the TIE is
negative)
BEGIN
WAIT UNTIL PPSInB'EVENT AND PPSInB='1';
PPSA2BSign<= PPSInA;
END PROCESS PPSAtoBSign;
PPSAtoBGate: PROCESS (PPSInA, RstGateAB)
BEGIN
IF RstGateAB='1' THEN
PPSGateAB<= '0';
ELSIF PPSInA'EVENT AND PPSInA='1' THEN
PPSGateAB<= '1';
END IF;
END PROCESS PPSAtoBGate;
PPSBtoAGate: PROCESS (PPSInB, RstGateBA)
BEGIN
IF RstGateBA='1' THEN
PPSGateBA<= '0';
ELSIF PPSInB'EVENT AND PPSInB='1' THEN
PPSGateBA<= '1';
END IF;
END PROCESS PPSBtoAGate;
PPSADelay: PROCESS
BEGIN
WAIT UNTIL Clock20'EVENT AND Clock20='1';
PPSADlyed<= PPSADlyed (3 downto 0)&PPSInA;
END PROCESS PPSADelay;
PPSBDelay: PROCESS
BEGIN
WAIT UNTIL Clock20'EVENT AND Clock20='1';
PPSBDlyed<= PPSBDlyed (3 downto 0)&PPSInB;
END PROCESS PPSBDelay;
PPSPhaseErrAB0: PROCESS (Clock100, PPSRstB) --Phase error counter bit 0
clocked by the gated 100MHz
BEGIN
IF PPSRstB='1' THEN
PPSPhaseCntAB (0)<= '1';
ELSIF Clock100'EVENT AND Clock100='1' THEN
IF PPSGateAB='1' AND StopCntAB='0' THEN
PPSPhaseCntAB (0)<= NOT PPSPhaseCntAB (0);
END IF;
END IF;
END PROCESS PPSPhaseErrAB0;
PPSPhaseErrAB: FOR I IN 1 TO 22 GENERATE
PPSPhaseErrABi: PROCESS (PPSPhaseCntAB (I-1), PPSRstB) --Phase error
counter bit 1
BEGIN
IF PPSRstB='1' THEN
PPSPhaseCntAB (I)<= '1';
ELSIF PPSPhaseCntAB (I-1)'EVENT AND PPSPhaseCntAB (I-1)='1' THEN
PPSPhaseCntAB (I)<= NOT PPSPhaseCntAB (I);
END IF;
END PROCESS PPSPhaseErrABi;
END GENERATE PPSPhaseErrAB;
PPSPhaseErrBA0: PROCESS (Clock100, PPSRstA) --Phase error counter bit 0
clocked by the gated 100MHz
BEGIN
IF PPSRstA='1' THEN
PPSPhaseCntBA (0)<= '0';
ELSIF Clock100'EVENT AND Clock100='1' THEN
IF PPSGateBA='1' AND StopCntBA='0' THEN
PPSPhaseCntBA (0)<= NOT PPSPhaseCntBA (0);
END IF;
END IF;
END PROCESS PPSPhaseErrBA0;
PPSPhaseErrBA: FOR I IN 1 TO 22 GENERATE
PPSPhaseErrBAi: PROCESS (PPSPhaseCntBA (I-1), PPSRstA) --Phase error down
counter
BEGIN
IF PPSRstA='1' THEN
PPSPhaseCntBA (I)<= '0';
ELSIF PPSPhaseCntBA (I-1)'EVENT AND PPSPhaseCntBA (I-1)='0' THEN
PPSPhaseCntBA (I)<= NOT PPSPhaseCntBA (I);
END IF;
END PROCESS PPSPhaseErrBAi;
END GENERATE PPSPhaseErrBA;
StopCntAB<= '1' WHEN PPSPhaseCntAB (22 downto 1)="0000000000000000000000"
ELSE '0';
StopCntBA<= '1' WHEN PPSPhaseCntBA (22 downto 1)="1111111111111111111111"
ELSE '0';
PPSPhaseLtc<= '0'&PPSPhaseCntBA WHEN PPSLtcA='1' AND PPSA2BSign='0' AND
StopCntBA='0' ELSE
'1'&PPSPhaseCntAB WHEN PPSLtcB='1' AND PPSA2BSign='1' AND StopCntAB='0' ELSE
PPSPhaseLtc;
OvrLtcAB<= StopCntAB WHEN PPSLtcB1='1' ELSE OvrLtcAB;
OvrLtcBA<= StopCntBA WHEN PPSLtcA1='1' ELSE OvrLtcBA;
RstGateAB<= '1' WHEN PPSInB='1' AND PPSBDlyed (1)='0' ELSE '0';
RstGateBA<= '1' WHEN PPSInA='1' AND PPSADlyed (1)='0' ELSE '0';
PPSLtcA<= '1' WHEN PPSADlyed="00011" ELSE '0';
PPSLtcA1<= '1' WHEN PPSADlyed="00001" ELSE '0'; --To be used by the
terminal count value
PPSRstA<= '1' WHEN PPSADlyed="01111" ELSE '0';
PPSLtcB<= '1' WHEN PPSBDlyed="00011" ELSE '0';
PPSLtcB1<= '1' WHEN PPSBDlyed="00001" ELSE '0'; --To be used by the
terminal count value
PPSRstB<= '1' WHEN PPSBDlyed="01111" ELSE '0';
PPSTIEOut<= "011111111111111111111111" WHEN OvrLtcAB='1' AND OvrLtcBA='1'
AND PPSPhaseLtc (23)='0' ELSE
"100000000000000000000000" WHEN OvrLtcAB='1' AND OvrLtcBA='1' AND
PPSPhaseLtc (23)='1' ELSE
PPSPhaseLtc;
END ARCHITECTURE RippleCounter;



On Mon, May 7, 2012 at 7:58 PM, <EWKehren at aol.com> wrote:

> 10 MHz between Rb and OCXO 1 pps between GPS and Rb.  Always a Rb with
>  GPS.
> Bert Kehren
>
>
> In a message dated 5/7/2012 1:30:57 P.M. Eastern Daylight Time,  azelio.
> boriani at screen.it writes:
>
> Using  the PPS as a sync source?
>
> On Mon, May 7, 2012 at 6:24 PM,  <EWKehren at aol.com> wrote:
>
> > Tried, no interest, some one has  offered to in the future do a gate
> array
> > version, you may want to wait  for that I am in the mean time using am
> > analog
> >  loop for  less than 100 seconds between Rb and OCXO and a very modified
> > Shera  for  GPS/Rb. Works for me.
> > Contact me off list and we can  talk.
> > Bert
> >
> >
> >
> > In a message dated 5/7/2012  12:05:54 P.M. Eastern Daylight Time,
> > garnere at gmail.com  writes:
> >
> > This is  something I would also like to know. I'm  sure many others
> > would be  interested as well. Bert would it be  possible for you to
> > share your  thoughts on the matter with the  group at large?
> >
> > -Eric
> >
> > On Mon,  May 7,  2012 at 8:43 AM,  <EWKehren at aol.com> wrote:
> > > Doc   contact me off list
> > > Bert Kehren
> > >
> > >
> >  > In a message  dated 5/7/2012 11:40:04 A.M. Eastern Daylight  Time,
> > >  docdailey at gmail.com writes:
> > >
> > >  Does  anyone have any  knowledge of a simple (just soldering a  few
> > > connections and  maybe programming a hz/volt rate) PCB  for
> synchronizing
> > a  precision
> > > OCXO to a   GPSDO?  I am trying to improve short  term stability with a
> >  high
> > > stability  OCXO and dont want to "cut  into" my  fury and replace the
> > OCXO.  I
> > > cando  it  manually  but this seems like it would be nice and desirable
> >  for
> > > many yet I  can't find anything.  I presume it  would have to be
> digital
> > >  because of  the long time  constant.
> > >
> > > Doc
> > >  KX0O
> >  >
> > > Sent from my  iPhone
> > >   _______________________________________________
> > > 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.
> > >
> > >   _______________________________________________
> > > time-nuts mailing  list  -- time-nuts at febo.com
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> >
> >
> >
> >  --
> > --Eric
> > _________________________________________
> >  Eric  Garner
> >
> >  _______________________________________________
> > time-nuts   mailing list -- time-nuts at febo.com
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