[ntp:questions] Re: Reference clocks - which?

Richard B. Gilbert rgilbert88 at comcast.net
Sat Oct 30 12:31:18 UTC 2004

Tapio Sokura wrote:

> Richard B. Gilbert wrote:
>> Tapio Sokura wrote:
>>> and it is working fine with an average of 1-2 satellites tracked. 
>>> When the position hold feature of the GPS receiver is used, one 
>>> satellite is enough for timing. Of course more is better and more 
>>> reliable, but 
>> I wish I knew how to do that.  With NTP 4.2.0 at 1.1161-r the Oncore 
>> driver seems to need 4 satellites in order to be "reachable"!  As a 
>> result, mine works only about thirty percent of the time.   For 
>> whatever reason, I get the best reception from about 9:00PM EDT to 
>> about 9:00AM.
> The setup I'm using is running ntpd 4.1.1a at 1.791 on Linux 2.2.19-nano, 
> I haven't bothered to update it for a while. I guess it is possible 
> that there have been changes to the driver since that or maybe you are 
> running a unit that doesn't have the position hold feature (I don't 
> even know whether there are such Oncores)? My /etc/ntp.oncore.1 file 
> looks like this:
> MODE 1
> LAT 60 3.1164
> LON 24 30.2508
> HT 28 M
> CHAN 6
> The relevant options here are MODE 1 and the three lines that follow 
> it specifying the location used for position hold. I have disabled 
> T-RAIM because the system seems to work better without it with only a 
> couple of satellites visible. This is a home system so continuous 
> reliability of the timing information is not that critical.
> ntp.conf has these two lines for my Oncore VP:
> pps /dev/oncore.pps.1 clear hardpps
> server prefer
>   Tapio

It seems clear that there have been a few changes to both the Oncore and 
the driver.  I have the Oncore M12+T.
I don't have "CLEAR" in ntp.oncore0; my Oncore uses the rising edge of 
the PPS signal.  I also don't have the pps line in ntp.conf.  The 4.2.0 
driver uses links in /dev named oncore.pps.0 and oncore.serial.0, both 
pointing to the serial port.   "hardpps" is still apparently an option 
but now is specified using the "flag3" parameter on the server 
statement.  I don't use hardpps either.   I will give hardpps a try.

Thanks for your response.

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