[ntp:questions] Fwd: Re: NetBSD GPS/PPS using 4.2.6p3

Link, Ken klink at osii.com
Fri Aug 26 15:53:23 UTC 2011

I run 4.2.6p3 with a Sure GPS in Linux and driver 20, but do not see an incoming message (to the device) every poll cycle (at all, actually).


Open Systems International, Inc.
Ken Link
Software Development

4101 Arrowhead Drive
Medina, Minnesota 55340-9457
Phone: 763 551 0559
Fax: 763 551 0750
E-mail: klink at osii.com
Website: http://www.osii.com/

-----Original Message-----

From: questions-bounces+klink=osii.com at lists.ntp.org [mailto:questions-bounces+klink=osii.com at lists.ntp.org] On Behalf Of unruh
Sent: Friday, August 26, 2011 9:24 AM
To: questions at lists.ntp.org
Subject: Re: [ntp:questions] Fwd: Re: NetBSD GPS/PPS using 4.2.6p3

On 2011-08-26, Steve Kostecke <kostecke at ntp.org> wrote:
> On 2011-08-26, David J Taylor <david-taylor at blueyonder.co.uk> wrote:
>> "A C" <agcarver+ntp at acarver.net> wrote:
>>> I'll still have to put a serial monitor on the line and try to figure
>>> out what is being transmitted towards the GPS when the PPS driver is
>>> active.
>> I noticed that when updating from ntpd 4.2.7p97 to ntpd 4.2.7p206,
>> I noticed that the newer version is sending some RS-232 data to the
>> GPS soon after the PPS signal has started. I filed a bug report about
>> this:
>>   http://bugs.ntp.org/show_bug.cgi?id=1999
> http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html states:
> "The driver will send a $PMOTG,RMC,000*1D<cr><lf> comand each poll
> interval. This is not needed on most GPS receivers because they
> automatically send $GPRMC every second, but helps a Motorola GPS
> receiver that is otherwise silent. NMEA devices ignore commands they do
> not understand."

That should surely be a flag, not a default. To send out sentences by
default that you know most units do not understand is irresponsible.
There is not guarentee that all others devices will ignore it. It is
also an ugly kludge which in 20 years should have received a better
(And are there any Motorola devices that still behave that way?)

> Searching for "PMOTG", using the doc.ntp.org search facility, reveals that
> the same text is present on:
> http://doc.ntp.org/4.1.2/drivers/driver20.html
> http://doc.ntp.org/4.2.0/drivers/driver20.html
> http://doc.ntp.org/4.2.4/drivers/driver20.html
> http://doc.ntp.org/4.2.6/drivers/driver20.html
> http://doc.ntp.org/4.2.6p1/drivers/driver20.html
> http://doc.ntp.org/4.2.6p2/drivers/driver20.html
> http://doc.ntp.org/4.2.6p3/drivers/driver20.html
> So this is not a new addition to ntp-dev.

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