[ntp:questions] Sure GPS - PPS not working

Chris North chris at invalid.com
Mon Dec 9 18:11:05 UTC 2013

"David Taylor"  wrote in message news:l84ss1$5ct$1 at dont-email.me...

On 09/12/2013 11:30, Chris North wrote:
> David,
> I have managed to fix it, and it was a bit unexpected. When I first 
> installed the Sure, I used a USB connection and got it working OK. I then 
> used a Serial-USB adapter and was pleased to find that it passed DCD and 
> that PPS was working. The jitter was rather high, though - about 0.3 mS. I 
> bought a 2-port serial PCI card and a serial cable, and immediately had a 
> massive improvement in performance. Recently, however, I found that PPS 
> had stopped working, as you have seen above.
> What I think happened was this: when I plugged in the new card it used the 
> standard Windows serial.sys, which I replaced with serialpps.sys. Now this 
> card is part of a range of multifunction cards that offer various I/O 
> interfaces. At some time Windows Update probably found the manufacturer's 
> drivers and installed them (automatically, or as an option that I just 
> accepted). The new driver ignores serial.sys and has its own software. So 
> I poked around in the registry and changed the ImagePath for one of the 
> card's new services to point to serialpps.sys. This seems to have fixed 
> it. As I don't use the COMn ports for anything else, I won't worry about 
> possible side-effects.

Good news, Chris.  I'm glad that my suggestion of looking at the driver
tree may have helped.  Quite possibly the same "update" issue happened
to me when I went from Windows 8.0 to 8.1, except that it wasn't quite
as obvious as a normal monthly update.  I better try and document that
somewhere - if I haven't already.

Web: http://www.satsignal.eu

Many thanks for your help, David. Having now sorted out the mess I had made 
of my Win 7 COM drivers, I have both 7 and 8.1 working properly.

I'm considering a Raspberry Pi standalone server. But, even after reading 
your excellent account, I am not too confident about the Linux stuff. I'll 
probably get hold of a Pi for experimenting. Did you get the Sure GPS 
working with the Pi? 

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