[time-nuts] Precision Time Protocol – Windows 10 implementation

[Adam Kumiszcza]

On Wed, Sep 25, 2019 at 8:01 PM David J Taylor via time-nuts <
time-nuts at lists.febo.com> wrote:

> From: Adam Kumiszcza
>
> Hi again!
>
> My raspi is now in a new location. The GPS signal is fine, the window is
> not south-facing, but the antenna is outside the window attached to a metal
> windowsill, and there are no buildings nearby.
> I'm coming back to the idea of distributing PPS signal. Do you think such a
> contraption could work?
>
> https://botland.com.pl/pl/raspberry-pi-hat-komunikacja/11707-serial-pi-plus-max3232-interfejs-rs232-dla-raspberry-pi-7426787870194.html
>
> I mean, stacking it over the uputronics board and soldiering some pins.
> The MAX3232 chip is the same as on these kind of devices:
>
> https://www.ebay.com/itm/MAX3232-RS232-to-TTL-Serial-Port-Converter-Module-DB9-Connector-MAX232/262241627343
>
> Cheers,
> Adam
> ===================================
>
> Adam,
>
> You need to consider what cable you will use, how many devices you need to
> feed, and what distance is involved.  I've fed a couple of PCs from the
> same
> RS232 device, just the data out and CD (PPS) lines, of course.  Not
> paralleling the data into the GPS device.  One PC is ~4m away, and the two
> signals are fed over a twin-pair coaxial cable.  Likely a 3-core
> unscreened
> cable would also be OK over such a short distance.  The other PC is about
> a
> metre away.
>
> If you're talking about ten PCs I would have a number of TTL to RS232
> converters, each feeding 2-3 PCs, or a controlled impedance cable (50 or
> 75
> ohms) with tap-offs along the cable and a termination at the far end.  The
> old thin-wire Ethernet comes to mind.
>
> But others here have more experience than me, though, and may be able to
> recommend surplus units to do the job.
>
> Cheers,
> David
>

It will be connected via a short cable (1,5 m or less) to one computer. The
second will join much later, I will worry about splitting the signal then.
Other computers would be in different rooms, so I would need another time
source.
My question was rather if stacking another board with serial port on it
would be a good idea. I'm thinking of using PPS signal there directly via
GPIO. And maybe NMEA, too.

Cheers,
Adam