[time-nuts] 4046 experiment for gpsdo

[Will]

Hi,

I'm new and trying to get to grips with things.

If I understand correctly, please forgive if I have it wrong,  This
locks a 10MHz signal  to a 1Hz (1pps) signal.  What makes it lock to 10
000 000Hz instead of 999 999Hz or 10 000 001Hz?  Just the hope that the
10MHz is exactly that?

Cheers,
Will

On 26/09/15 08:32, Jim Harman wrote:
> To further demonstrate the Diode - R- C- approach, here  (hopefully) is a
> screenshot of the raw DAC output vs time on my Arduino Micro (32u4) based
> system. For this test the oscillator is free running with an error of about
> 1 usec per 460 sec or 2.17x10^-9. The horizontal scale is 125 sec/div (1000
> sec total) and the vertical is 1024  DAC counts (0-2.56 V) which
> corresponds to 1 usec of offset between the oscillator and the reference.
>
> You can see that there is some curvature because the capacitor is being
> charged through a resistor and not a true current source, but as I
> mentioned earlier this does not affect the system's ability to lock the
> oscillator to the pps reference. When locked with a time constant of 1000
> sec, the phase detector output is almost always less than +/- 100 counts
> from the setpoint of 500.
>
> The noise is due mostly to jitter in my PPS reference, which is generated
> by an Adafruit GPS module. Presumably it would be less if I had a real
> timing receiver.
>
>
> ​.
> If the inserted image does not come through, I will re-send as an
> attachment.
>
>> --
> --Jim Harman
>
>
>
> _______________________________________________
> 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.