[ntp:questions] Sure GPS - PPS not working

Chris North chris at invalid.com
Mon Dec 9 11:30:17 UTC 2013

"David Taylor"  wrote in message news:l82ft0$71s$1 at dont-email.me...

OK, Chris, so it's not a hardware issue.  I don't know the message:

   "Exec format error"

on Windows, but it sounds like the support DLL or driver isn't right.
When you list the COM1 device in the device manager, does it show the
serialpps.sys in the list of drivers?  If you right-click, Properties
the .SYS or .DLL files, do they show the Unblock button.  Perhaps
compare the files against those froma fresh download using a binary

   fc /b <working-file>  <dowloaded-file>

Although it doesn't affect you, I recall that the Windows 8.0 to 8.1
upgrade required re-installation of a couple of drivers (one unsigned)
which I needed.

Web: http://www.satsignal.eu


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 

Just to show the difference -

     remote           refid      st t when poll reach   delay   offset 
*GPS_NMEA(1)     .GPS.            0 l    5    8  377    0.000   -0.036 
-    2 u   28   64  377   22.674   -4.448 
+betelgeuse.retr    2 u   15   64  377   22.621   -2.651 
+ntp2.websters-c     2 u    -   64  377   25.693   -3.363 

     remote           refid      st t when poll reach   delay   offset 
oPPS(1)          .PPS.            0 l    -    8  377    0.000   -0.023 
*GPS_NMEA(1)     .GPS.            0 l    7    8  377    0.000   -0.038 
+ntp.teaparty.ne  3 u   24   64  377   25.227   -3.584 
+ntppub.le.ac.uk    2 u   41   64  377   26.930   -3.834 
-orgin.sorch.inf     2 u   64   64  377   25.760   -3.058 

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