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

[David J Taylor]

> You already have a PPS signal from your existing GPS, so I was thinking
> simply of distributing that the the Windows PCs, and feeding it to the
> serial port's DCD signal.
>

I will try that. I guess you can connect serial port directly to my
Uputronics expansion card (
https://store.uputronics.com/index.php?route=product/product&path=60_64&product_id=81)
while still attached to Raspberry Pi. Problem is, I'm a software, not a
hardware guy. No idea about soldering. Time to learn a new skill :)

If the PC doesn't have a serial port, check on the motherboard because
> there
> are sometimes serial port headers left unconnected by the PC manufacturer.
>

That's exactly in my case. Motherboard manual says the serial port
expansion is sold separately.

[..] Check with your Android mobile phone
> what the GPS signal levels actually are in your possible locations - I
> think
> Apple don't allow you to access that information.


I don't have access to any Android device :( I'll try to use gpsmon or
other tool to check GPS signal level (S/N ratio of satellites should be
sufficient, I guess?).


> The key here is to have some conducting magnetic material under the
> antenna,
> not just sitting on its own.


My GPS antenna hangs on the window handle and still gives the good result.
It's on the south facing window. Unfortunately, in the new location I will
have access only to west facing window.
Why is it good to have some conducting magnetic material under the antenna?
Is it to reduce multipath?

Best regards,
Adam
===========================

Adam,

Be aware that the signals from the Uputronics board (and similar) are most 
likely to be at a 3.3V level, which /may/ not be sufficient to drive the DCD 
pin on a traditional RS232 port, and you may need a level converter.  You 
don't need to connect the other lines - send & receive - just the DCD and 
ground.  I have a simple program which enables you to check for the pulsing 
of the DCD line (and the other lines too):

  https://www.satsignal.eu/software/net.htm#SerialPortLEDs

Yes, if you can use cgps or similar that would be fine - I just find the 
phone handier!

The puck antennas are designed for use with a ground plane, and the maximum 
pickup is then at 90 degrees to the ground-plane.  I don't think that on 
these cheap antennas there's any multipath reduction, just more gain from 
having the ground plane.  Be aware that in the new location the glass may 
have some attenuation at 1.5 GHz as used by GPS.

Cheers,
David
-- 
SatSignal Software - Quality software for you
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk
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