[time-nuts] TCVCXO Adjustment

Adrian Godwin artgodwin at gmail.com
Sat Apr 14 06:35:39 EDT 2018


If you compare VCXO time with UTC or GPS once a month to an accuracy of 1s
(with NMEA or even a time signal and manual pushbutton) and make a
correction for the 2.5 million seconds that occurred since the last
correction, you'll be better than 0.5 ppm.

Is that good enough ?

On Sat, Apr 14, 2018 at 5:59 AM, Hal Murray <hmurray at megapathdsl.net> wrote:

>
> kb8tq at n1k.org said:
> > The alternative is to plug a USB GPS into the mac and do a bit of code to
> > compare things. If you want to pass the gizmo around to your friends ….
> that
> > can be done. Pretty good ones are “sub $10” delivered.
>
> USB GPS gizmos generally don't have a PPS and the timing on the NMEA
> sentences is generally crappy.  (I may be biased by a few bad examples.)
>
> Does anybody have a list of ones known to work well?
>
> There is at least one GPS-USB with PPS, the Navisys
> GR-601W/GR-701W/GR-801W,
> They were hard to get retail.  Looks like idealez sells them Taiwan for
> $47
> for the 701W (Ublox 7), $50 for the 801W (Ublox 8) (plus shipping).  I
> haven't tried ordering through them.  Gary and/or Mark may have some for
> sale.
>
> ----------
>
> Plan B is a GPS breakout and a USB-serial breakout and a few wires.  4x
> less
> USB jitter if your USB-Serial chip is full-speed.
>
> I got mine from SparkFun:
> Venus GPS with SMA Connector
>   https://www.sparkfun.com/products/11058
> USB to Serial Breakout - FT232RL
>   https://www.sparkfun.com/products/12731
>
> ----------
>
> Google found this.  I don't know anything more:
>   https://www.zti-communications.com/z050-gps-dongle/
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
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