[ntp:questions] help with setting up NTP on windows with a USB GPS

Dave Baxter spam at goes.nowhere.com
Fri Dec 4 09:57:26 UTC 2009

In article <517b0b0d-1557-4c0e-b6b4-2d92d627258c@
2g2000prl.googlegroups.com>, davehart at gmail.com says...
> On Dec 1, 13:58 UTC, Dave Baxter wrote:
> > What colateral effects will the serialpps.sys driver have on the other
> > com port, as that will be used for controling the radio (data lines
> > only.)   Also, what effect would it have on, or be affected by, the CPU
> > loading of the needed DSP routines that kick off once every few seconds.
> The effect compared to using serial.sys is quite similar.
> serialpps.sys adds a new "ioctl" which software other than ntpd won't
> know about or use.  Until the first time that ioctl is called by a
> given process, serial.sys behaves identically.  After the first call
> to that ioctl, the interrupt handler for "modem status" line changes
> (including DCD) squirrels away a system timestamp and cycle counter
> value at each DCD clear->asserted transition, retrievable via the same
> ioctl.
> serialpps.sys timekeeping performance compared to the "user-mode PPS"
> hack is relatively marginal under optimal circumstances, as David
> Taylor has demonstrated.  The more loaded the box, the more likely
> serialpps.sys's interrupt-time timestamping of DCD will be
> substantially more accurate than ntpd doing the same thing from user
> mode.
> Cheers,
> Dave Hart

Hi Dave..

I tried last night to "install" your serialPPS driver, onto the Win2k 
machine I have temporaraly made available to try all this.

Sadly, all I get are errors like...

"'reg' is not recognized as an internal or external command,
operable program or batch file."

So, I guess it's a delicate manual install for Windows then?  XP has the 
'reg' command, but 2000 does not.

Appologies if you've answered this in the past, but I can never seem to 
go back in time, with these news reader systems, and Google Groups wont 
let me in at the moment.

Dave Baxter.

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