[ntp:questions] Sure GPS - PPS not working

David Taylor david-taylor at blueyonder.co.uk.invalid
Sun Dec 8 16:57:30 UTC 2013

On 08/12/2013 16:36, Chris North wrote:
> Most of the discussion here is way above my head, but I'm hoping
> somebody will be able to help me.
> I have a Sure GPS board, modified according to David Taylor's plan,
> connected to a Windows 7 PC by USB (for power only) and by serial
> null-modem cable to COM1 on a PCI serial card.
> I am running ntpd 4.2.7p401 and have installed the signed serialpps.sys
> (14.May.2012 16:08) in place of the standard serial.sys driver. I have
> also installed the serialpps-ppsapi-provider.dll with a suitable value
> for the PPSAPI_DLLS environment variable.
> When I first set this up a year or more ago, I got the GPS_NMEA and PPS
> entries displayed in the output from ntpq. However, I have just realised
> that PPS is no longer there. NTP is still giving reasonable accuracy -
> adequate for my needs - but I'd still like to get PPS working again.
> Can anybody suggest anything useful, please?

First question - is the blue PPS LED on the Sure board flashing?  Well, 
I thought you will have already checked that.

Second, stop the NTP service and see whether my serial port LEDs program:


can see the PPS signal.  You might be able to isolate any hardware 
problems with these two tests.  It seems unlikely to be a software 
problem as I have the same setup working on a Windows-7/64 and a 
Windows-8.1/64 PC, to which the various updated have been applied. 
Perhaps the lead to the COM1 port has fallen out?

Web: http://www.satsignal.eu

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